Ada Web Server
**************

Introduction
************

AWS stand for Ada Web Server. It is an Ada implementation of the HTTP/1.1 protocol as defined in the RFC 2616 from June 1999.

The goal is not to build a full Web server but more to make it possible to use a Web browser (like Internet Explorer, or Netscape Navigator) to control an Ada application. As we'll see later it is also possible to have two Ada programs exchange informations via the HTTP protocol. This is possible as AWS also implement the client side of the HTTP protocol.

Moreover with this library it is possible to have more than one server in a single application. It is then possible to export different kind of services by using different HTTP ports, or to have different ports for different services priority. Client which must be served with a very high priority can be assigned a specific port for example.

As designed, AWS big difference with a standard CGI server is that there is only one executable. A CGI server has one executable for each request or so, this becomes a pain to build and to distribute when the project gets bigger. We will also see that it is easier with AWS to deal with session data.

AWS support also HTTPS (secure HTTP) using SSL. This is based on OpenSSL a very good and Open Source SSL implementation.

Major supported features are:

  * HTTP implementation

  * HTTPS (Secure HTTP) implementation based on SSLv3

  * Template Web pages (separate the code and the design)

  * Web Services - SOAP based

  * WSDL support (generate stub/skeleton from WSDL documents)

  * Basic and Digest authentication

  * Transparent session handling (server side)

  * HTTP state management (client side cookies)

  * File upload

  * Server push

  * SMTP / POP (client API)

  * LDAP (client API)

  * Embedded resources (full self dependant Web server)

  * Complete client API, including HTTPS

  * Web server activity log

Building AWS
************

Requirements
============

AWS has been mainly developed with GNAT on Windows. It is built and tested regularly on GNU/Linux and Solaris, it should be fairly portable across platforms. To build AWS you need:

  * GNU/Ada (GNAT compiler) ;

     To build this version you need at least GNAT GPL 2009 Edition or GNAT Pro 6.2 as some Ada 2005 fearures (Ada.Containers, interfaces, overriding keyword) are used. The code should be fairly portable but has never been tested on another compiler than GNAT.

  * OpenSSL (optional) ;

     OpenSSL is an Open Source toolkit implementing the Secure Sockets Layer (SSL v2 and v3) and much more. You'll find libraries for Win32 into this distribution. For other platforms just download the OpenSSL source distribution from http://www.openssl.org and build it.

  * OpenLDAP (optional) ;

     OpenLDAP is an Open Source toolkit implementing the Lightweight Directory Access Protocol. If you want to use the AWS/LDAP API on UNIX based systems, you need to install properly the OpenLDAP package. On Windows you don't need to install it as the libldap.a library will be built by AWS and will use the standard Windows LDAP DLL wldap32.dll.

     You can download OpenLDAP from http://www.openldap.org.

AWS.Net.Std
===========

This package is the standard (non-SSL) socket implementation. It exists different implementations of this package:

IPv4

     Version based on GNAT.Sockets. This is the default implementation used.

IPv6

     As above but supporting IPv6 protocol. To select this implementation just do when building (see below):

          {$ make IPv6=true}

Building
========

Before building be sure to edit makefile.conf, this file contains many settings important for the build. Note that it is important to run make setup each time you edit this file.

When you have built and configured all external libraries you must set the ADA_PROJECT_PATH variable to point to the GNAT Project files for the different packages. For XML/Ada support, you also need to set XMLADA to TRUE in makefile.conf.

At this point you can build AWS with:

     {$ make setup build}

Note that some demos require that AWS be built with SSL support. If you want to activate SSL on UNIX (in this case you must have libssl.a and libcrypto.a available on your platform), open makefile.conf and set the SOCKET variable to openssl. Then rebuild with:

     {$ make setup build}

It is is possible to build AWS in debug mode by setting DEBUG make's variable in makefile.conf, or just:

     {$ make DEBUG=true setup build}

Note that by default AWS is configured to use the GNAT compiler. So, if you use GNAT you can build AWS just with:

     {$ make setup build}

If you want to build only the AWS libraries and tools and do not want to build the demos you can set DEMOS to "false" as in:

     {$ make DEMOS=false setup}

Building on cross-platforms
===========================

To build for a cross platform the TARGET makefile variable must be set with the cross toolchain to be used. The value must be the triplet of the toolchain to use.

For example, to build on VxWorks:

     {$ make TARGET=powerpc-wrs-vxworks setup build}

Demos
=====

AWS comes with some ready to use demos. The demos are a good way to learn how to use AWS.

Here are a short description of them:

agent

     A program using the AWS client interface. This simple tool can be used to retrieve Web page content. It supports passing through a proxy with authentication and basic authentication on the Web site.

auth

     A simple program to test the Web Basic and Digest authentication feature.

com

     Two simples program that uses the AWS communication service.

dispatch

     A simple demo using the dispatcher facility. see URI dispatcher.

hello_world

     The famous Hello World program. This is a server that will always return a Web page saying ``Hello World!''.

hotplug

     A simple test for the hotplug feature.

interoplab

     A WSDL based demo that test most of the SOAP features.

jabber_demo

     A simple Jabber command line client to check the presence of a JID (Jabber ID). This uses the Jabber API, see AWS.Jabber.

multiple_sessions

     A demo of two embedded servers using different sessions.

res_demo

     A demo using the resource feature. This Web Server embedded a PNG image and an HTML page. The executable is self contained.

runme

     An example that test many AWS features.

soap_demo

     A simple client/server program to test the SOAP protocol.

soap_disp

     Like above but use a SOAP dispatcher.

soap_vs

     A client and server that implement seven SOAP procedures for testing purpose.

split

     A demo for the transient pages and page splitter AWS's feature. Here a very big table is split on multiple pages. A set of links can be used to navigate to the next or previous page or to access directly to a given page.

test_ldap

     A simple LDAP demo which access a public LDAP server and display some information.

test_mail

     A simple application that send a set of SMTP messages with different kind of attachments.

text_input

     A simple demo which handle textarea and display the content.

vh_demo

     Two servers on the same machine... virtual hosting demo. see Virtual host dispatcher.

web_block

     A simple Web Bock based counter.

web_block_ajax

     As above but using also Ajax.

web_block_ajax_templates

     As above but using also the templates2ada tool which create a tight coupling between the web templates and the Ada code.

web_elements

     A driver to browse the Web Elements library and see some examples.

web_mail

     A simple Web Mail implementation that works on a POP mailbox.

wps

     A very simple static Web page server based on AWS.Services.Page_Server. see Static Page server.

ws

     A static Web page server and push enabled server.

zdemo

     A simple demo of the Gzip content encoding feature.

For build instructions see demos/README.

Installing
==========

When the build is done you must install AWS at a specific location. The target directory is defined with the PREFIX makefile.conf variable. The default value is set to the compiler root directory. Note that the previously installed version is automatically removed before installing the new one. To install:

     {$ make install}

To install AWS into another directory you can either edit makefile.conf and set PREFIX to the directory you like to install AWS or just force the make PREFIX variable:

     {$ make prefix=/opt install}

Alternatively, with GNAT 5.03 and above it is possible to install AWS into the GNAT Standard Library location. In this case AWS is ready-to-use as there is no need to set ADA_PROJECT_PATH, just set PREFIX to point to GNAT root directory:

     {$ make prefix=/opt/gnatpro/6.1.1 install}

Now you are ready to use AWS !

Using AWS
*********

Setting up environment
======================

Using environment variables
---------------------------

After installing AWS you must set the build environment to point the compiler to the right libraries. First let's say that AWS has been installed in awsroot directory.

Following are the instructions to set the environment yourself. Note that the preferred solution is to use project files. In this case there is no manual configuration.

spec files

     The spec files are installed in <awsroot>/include/aws. Add this path into ADA_INCLUDE_PATH or put it on the command line -aI<awsroot>/include/aws.

components

     AWS uses some components they are installed in <awsroot>/include/aws/components. Add this path into ADA_INCLUDE_PATH or put it on the command line -I<awsroot>/include/aws/components.

libraries

     The GNAT library files (.ali) and the AWS libraries (libaws.a) are installed into <awsroot>/lib/aws/static. Add this path into ADA_OBJECTS_PATH or put it on the command line -aO<awsroot>/lib/aws/static. Furthermore for gnatlink to find the libraries you must add the following library path option on the gnatmake command line -largs -L<awsroot>/lib/aws/static -laws.

     Note that to build SSL applications you need to add -lssl -lcrypto on gnatmake's -largs section.

external libraries

     You must do the same thing (setting ADA_INCLUDE_PATH and ADA_OBJECTS_PATH) for all external libraries that you will be using.

Using GNAT Project Files
------------------------

The best solution is to use the installed GNAT Project File aws.gpr. This is supported only for GNAT 5.01 or above. You must have installed XML/Ada with project file support too.

If this is the case just set the ADA_PROJECT_PATH variable to point to the AWS and XML/Ada install directories. From there you just have to with the AWS project file in your GNAT Project file, nothing else to set.

     {with "aws";

project Simple is

for Main use ("prog.adb");

for Source_Dirs use ("src");

for Object_Dir use "obj";

end Simple;

See the GNAT User's Guide for more information about GNAT Project Files.

Basic notions
=============

AWS is not a Web Server like IIS or Apache, it is a component to embedded HTTP protocol in an application. It means that it is possible to build an application which can also answer to a standard browser like Internet Explorer or Netscape Navigator. Since AWS provides support client and server HTTP protocol, applications can communicate through the HTTP channel. This give a way to build distributed applications, see AWS.Client.

An application using AWS can open many HTTP channels. Each channel will use a specific port. For example, it is possible to embedded many HTTP and/or many HTTPS channels in the same application.

Building an AWS server
----------------------

To build a server you must:

 1. declare the HTTP Web Server

          {WS  : AWS.Server.HTTP;}

 2. Start the server

     You need to start the server before using it. This is done by calling AWS.Server.Start (see AWS.Server.)

          {procedure Start

     (Web_Server                : in out HTTP; Name                      : in     String; Callback                  : in     Response.Callback; Max_Connection            : in     Positive     := Def_Max_Connect; Admin_URI                 : in     String       := Def_Admin_URI; Port                      : in     Positive     := Def_Port; Security                  : in     Boolean      := False; Session                   : in     Boolean      := False; Case_Sensitive_Parameters : in     Boolean      := True; Upload_Directory          : in     String       := Def_Upload_Dir); --  Start the Web server. It initialize the Max_Connection connections --  lines. Name is just a string used to identify the server. This is used --  for example in the administrative page. Admin_URI must be set to enable --  the administrative status page. Callback is the procedure to call for --  each resource requested. Port is the Web server port. If Security is --  set to True the server will use an HTTPS/SSL connection. If Session is --  set to True the server will be able to get a status for each client --  connected. A session ID is used for that, on the client side it is a --  cookie. Case_Sensitive_Parameters if set to False it means that the CGI --  parameters name will be handled without case sensitivity. Upload --  directory point to a directory where uploaded files will be stored.

     Start takes many parameters:

     Web_Server

          this is the Web server to start.

     Name

          This is a string to identify the server. This name will be used for example in the administrative status page.

     Callback

          This is the procedure to call for each requested resources. In this procedure you must handle all the possible URI that you want to support. (see below).

     Max_Connection

          This is the maximum number of simultaneous connections. It means that Max_Connection client's browsers can gets answer at the same time. This parameter must be changed to match your needs. A medium Web server will certainly need something like 20 or 30 simultaneous connections.

     Admin_URI

          This is a special URI recognized internally by the server. If this URI is requested the server will return the administrative page. This page is built using a specific template page (default is
          _STATUS_PAGE_}) see Status page.

          The administrative page returns many information about the server. It is
          possible to configure the server via two configuration files
          see Configuration options.

     Port

          This is the port to use for the Web server. You can use any free port on your computer. Note that on some OS specific range could be reserved or needs specials privileges (port 80 on Linux for example).

     Security

          If Security is set to True the server will use an HTTPS/SSL connection. This part uses the OpenSSL library.

     Session

          If Session is set to true the server will keep a session ID for each client. The client will be able to save and get variables associated with this session ID.

     Case_Sensitive_Parameters

          If set to True the CGI name parameters will be handled without using the case.

     Note that there is other Start routines which support other features. For example there is a Start routine which use a dispatcher routine instead of the simple callback procedure. see AWS.Server. And there is also the version using a Config.Object which is the most generic one.

 3. provides a callback procedure

     The callback procedure has the following prototype:

          {function Service (Request : in AWS.Status.Data) return AWS.Response.Data;}

     This procedure receive the request status. It is possible to retrieve information about the request through the AWS.Status API (see AWS.Status.).

     For example, to know what URI has been asked:

          {URI : constant String := AWS.Status.URI (Request);

     if URI = "/whatever" then ... end if;

     Then this function should return an answer using one of the constructors in AWS.Response (see AWS.Response.). For example, to return an HTML message:

          {AWS.Response.Build (Content_Type => "text/html",

     Message_Body => "<p>just a demo");

     It is also possible to return a file. For example, here is the way to return a PNG image:

          {AWS.Response.File (Content_Type => "image/png",

     Filename     => "adains.png");

Note that the main procedure should exit only when the server is terminated. For this you can use the AWS.Server.Wait service.

A better solution is to use a template engine like Templates_Parser to build the HTML Web Server answer. Templates_Parser module is distributed with this version of AWS.

Callback procedure
------------------

The callback procedure is the user's code that will be called by the AWS component to get the right answer for the requested resource. In fact AWS just open the HTTP message, parsing the HTTP header and it builds an object of type AWS.Status.Data. At this point it calls the user's callback procedure, passing the object. The callback procedure must returns the right response for the requested resources. Now AWS will just build up the HTTP response message and send it back to user's browser.

But what is the resource ?

Indeed in a standard Web development a resource is either a static object - an HTML page, an XML or XSL document - or a CGI script. With AWS a resource is just a string to identify the resource, it does not represent the name of a static object or CGI script.

So this string is just an internal representation for the resource. The callback procedure must be implemented to handle each internal resource and return the right response.

Let's have a small example. For example we want to build a Web server that will answer ``Hello World'' if we ask for the internal resource /hello, and must answer ``Hum...'' otherwise.

     {with AWS.Response;

with AWS.Server; with AWS.Status;

procedure Hello_World is

WS : AWS.Server.HTTP;

function HW_CB (Request : in AWS.Status.Data) return AWS.Response.Data is URI : constant String := AWS.Status.URI (Request); begin if URI = "/hello" then return AWS.Response.Build ("text/html", "<p>Hello world !"); else return AWS.Response.Build ("text/html", "<p>Hum..."); end if; end HW_CB;

begin AWS.Server.Start (WS, "Hello World", Callback => HW_CB'Unrestricted_Access); delay 30.0; end Hello_World;

Now of course the resource internal name can represent a file on disk. It is not mandatory but it is possible. For example it is perfectly possible to build with AWS a simple page server.

As an example, let's build a simple page server. This server will returns files in the current directory. Resources internal name represent an HTML page or a GIF or PNG image for example. This server will return a 404 message (Web Page Not Found) if the file does not exist. Here is the callback procedure that implements such simple page server:

     {function Get (Request : in AWS.Status.Data) return AWS.Response.Data is

URI      : constant String := AWS.Status.URI (Request); Filename : constant String := URI (2 .. URI'Last); begin if Utils.Is_Regular_File (Filename) then return AWS.Response.File (Content_Type => AWS.MIME.Content_Type (Filename), Filename     => Filename);

else return AWS.Response.Acknowledge (Messages.S404, "<p>Page '" & URI & "' Not found."); end if; end Get;

Form parameters
---------------

Form parameters are stored into a table of key/value pair. The key is the form input tag name and the value is the content of the input field as filled by the user.

     {Enter your name

<FORM METHOD=GET ACTION=/get-form>" <INPUT TYPE=TEXT NAME=name VALUE="<default>" size=15> <INPUT TYPE=SUBMIT NAME=go VALUE="Ok"> </FORM>

Note that as explained above see Callback procedure, the resource described in ACTION is just an internal string representation for the resource.

In this example there is two form parameters:

name
     The value is the content of this text field as filled by the client.

go
     The value is "Ok".

There is many functions (in AWS.Parameters) to retrieve the tag name or value and the number of parameters. Here are some examples:

     {function Service (Request : in AWS.Status.Data)

return AWS.Response.Data is P : constant AWS.Parameters.List := AWS.Status.Parameters (Request); ...

AWS.Parameters.Get (P, "name")
     Returns the value for parameter named name

AWS.Parameters.Get_Name (P, 1)
     Returns the string "name".

AWS.Parameters.Get (P, 1)
     Returns the value for parameter named name

AWS.Parameters.Get (P, "go")
     Returns the string "Ok".

AWS.Parameters.Get_Name (P, 2)
     Returns the string "go".

AWS.Parameters.Get (P, 2)
     Returns the string "Ok".

Request is the AWS current connection status passed to the callback procedure. And P is the parameters list retrieved from the connection status data. For a discussion about the callback procedure see Building an AWS server.

Distribution of an AWS server
-----------------------------

The directory containing the server program must contain the following files if you plan to use a status page see Status page.

_STATUS_PAGE_

     The template HTML file for the AWS status page.

_LOGO_IMAGE_

     The AWS logo displayed on the status page.

_UP_IMAGE_

     The AWS hotplug table up arrow.

_DOWN_IMAGE_

     The AWS hotplug table down arrow.

Note that these filenames are the current AWS default. But it is possible to change those defaults using the configuration files see Configuration options.

Building answers
================

We have already seen, in simple examples, how to build basic answers using AWS.Response API. In this section we present all ways to build answers from basic support to the more advanced support like the compressed memory stream response.

Redirection
-----------

A redirection is a way to redirect the client's browser to another URL. Client's won't notice that a redirection has occurs. As soon as the browser has received the response from the server it will retrieve the page as pointed by the redirection.

     {return Response.URL (Location => "/use-this-one");}

New location for a page
-----------------------

User will receive a Web page saying that this page has moved and eventually pointing to the new location.

     {return Response.Moved

(Location => "/use-this-one"; Message  => "This page has moved, please update your reference");

Authentication required
-----------------------

For protected pages you need to ask user to enter a password. see Authentication.

Sending back an error message
-----------------------------

Acknowledge can be used to send back error messages. There is many kind of status code, see Message.Status_Code definition. Together with the status code it is possible to pass textual error message in Message_Body parameter.

     {return Response.Acknowledge

(Status_Code  => Messages.S503, Message_Body => "Can't connect to the database, please retry later.", Content_Type => MIME.Text_Plain);

Response from a string
----------------------

This is the simplest way to build a response object. There is two constructors in AWS.Response, one based on a standard string and one for Unbounded_String.

     {return Response.Build (MIME.Text_HTML, "My answer");}

The Build routine takes also a status code parameter to handle errors. By default this code is Messages.S200 which is the standard HTTP status (no error encountered). The other parameter can be used to control caches. see AWS.Response.

Response from a Stream_Element_Array
------------------------------------

This is exactly as above but the Build routine takes a Stream_Element_Array instead of a string.

Response from a file
--------------------

To build a File response there is a single constructor named File. This routine is very similar to the one above except that we specify a filename as the response.

     {return Response.File (MIME.Text_HTML, "index.html");}

Again there parameters to control the status code and cache. No check on the filename is done at this point, so if index.html does not exit no exception is raised. The server is responsible to check for the file and to properly send back the 404 message if necessary.

Note that this routine takes an optional parameter named Once that is to be used for temporary files created on the server side for the client. With Once set to True the file will be deleted by the server after sending it (this includes the case where the download is suspended).

Response from a stream
----------------------

Sometimes it is not possible (or convenient) to build the response in memory as a string object for example. Streams can be used to workaround this. The constructor for such response is again very similar to the ones above except that instead of the data we pass an handle to a Resources.Streams.Stream_Type object.

The first step is to build the stream object. This is done by deriving a new type from Resources.Streams.Stream_Type and implementing three abstract procedures.

Read

     Must return the next chunk of data from the stream. Note that initialization if needed are to be done there during the first call to read.

End_Of_File

     Must return True when there is no more data on the stream.

Close

     Must close the stream and for example release all memory used by the implementation.

The second step is to build the response object:

     {type SQL_Stream is new Resources.Streams.Stream_Type;

Stream_Object : SQL_Stream;

procedure Read (...) is ... function End_Of_File (...) return Boolean is ... procedure Close (...) is

...

return Response.Stream (MIME.Text_HTML, Stream_Object);

Note that in some cases it is needed to create a file containing the data for the client (for example a tar.gz or a zip archive). But there is no way to properly remove this file from the file system as we really don't know when the upload is terminated when using the AWS.Response.File constructor. To solve this problem it is possible to use a stream as the procedure Close is called by the server when all data have been read. In this procedure it is trivial to do the necessary clean-up.

Response from a on-disk stream
------------------------------

An ready-to-use implementation of the stream API described above where the stream content is read from an on-disk file.

Response from a on-disk once stream
-----------------------------------

An ready-to-use implementation of the stream API described above where the stream content is read from an on-disk file. When the transfer is completed the file is removed from the file system.

Response from a memory stream
-----------------------------

This is an implementation of the standard stream support described above. In this case the stream is in memory and built by adding data to it.

To create a memory stream just declare an object of type AWS.Resources.Streams.Memory.Stream_Type. When created, this memory stream is empty, using the Streams.Memory.Append routines it is possible to add chunk of data to it. It is of course possible to call Append as many times as needed. When done just return this object to the server.

     {Data : AWS.Resources.Streams.Memory.Stream_Type;

Append (Data, Translator.To_Stream_Element_Array ("First chunk")); Append (Data, Translator.To_Stream_Element_Array ("Second chunk..."));

...

return Response.Stream (MIME.Text_HTML, Data);

Note that you do not have to take care of releasing the allocated memory, the default Close routine will do just that.

Response from a compressed memory stream
----------------------------------------

This is a slight variant of the standard memory stream described above. In this case the stream object must be declared as a AWS.Resources.Streams.Memory.ZLib.Stream_Type.

The ZLib stream object must be initialized to enable the compression and select the right parameters. This is done using the AWS.Resources.Streams.Memory.ZLib.Deflate_Initialize routine which takes many parameters to select the right options for the compression algorithm, all of them have good default values. When initialized the compressed stream object is used exactly as a standard stream.

     {Data : AWS.Resources.Streams.Memory.ZLib.Stream_Type;

Deflate_Initialize (Data);

Append (Data, Translator.To_Stream_Element_Array ("First chunk")); Append (Data, Translator.To_Stream_Element_Array ("Second chunk..."));

...

return Response.Stream (MIME.Text_HTML, Data);

Note that there is the reverse implementation to decompress a stream. see AWS.Resources.Streams.Memory.ZLib. It's usage is identical.

Split page
----------

AWS has a specific high level service to split a large response into a set of pages. For more information see Split pages.

Response a from pipe stream
---------------------------

The response sent to the server is read from the output of an external application. This kind of stream can be used to avoid writing a temporary file into the hard disk. For example it is possible to return an archive created with the tar tool without writting the intermediate tar achive on the disk.

Configuration options
=====================

To configure an AWS server it is possible to use a configuration object. This object can be set using the AWS.Config.Set API or initialized using a configuration file.

Configuration files are a way to configure the server without recompiling it. Each application can be configured using two configurations files:

aws.ini

     This file is parsed first and corresponds to the configuration for all AWS server runs in the same directory.

<program_name>.ini

     This file is parsed after aws.ini. It is possible with this initialization file to have specific settings for some servers. program_name.ini is looked first in the application's directory and then in the current working directory. This is only supported on platforms where Ada.Command_Line is implemented. So, on VxWorks only aws.ini is parsed.

Furthermore, it is possible to read a specific configuration file using the AWS.Config.Ini.Read routine. see AWS.Config.Ini.

Current supported options are:

Accept_Queue_Size (positive)
     This is the size of the queue for the incoming requests. Higher this value will be and less "connection refused" will be reported to the client. The default value is _QUEUE_SIZE_.

Admin_Password (string)
     This is the password used to call the administrative page. The password can be generated with aws_password (the module name must be ADMIN)

          {$ aws_password admin <password>}

Admin_URI (string)
     This is the URI to call the administrative page. This can be used when
     calling AWS.Server.Start. The default is _ADMIN_URI_}.

Certificate (string)
     Set the certificate file to be used with the secure servers. The
     default is _DEFAULT_CERTIFICATE_}. A single certificate or a
     certificate chain is supported. The certificates must be in PEM format
     and the chain must be sorted starting with the subject's certificate, followed
     by intermediate CA certificates if applicable and ending at the highest
     level (root) CA certificate. If the file contains only a single
     certificate, it can be followed by a private key. In this case the Key
     parameter (see below) must empty.

Case_Sensitive_Parameters (boolean)
     If set to True the HTTP parameters are case sensitive. The default value is _CASE_SENSITIVE_PARAMETERS_.

Check_URL_Validity (boolean)
     Server have to check URI for validity. For example it checks that an URL does not reference a resource above the Web root. The default is _CHECK_URL_VALIDITY_.

Cleaner_Wait_For_Client_Timeout (duration)
     Number of seconds to timeout on waiting for a client request. This is a timeout for regular cleaning task. The default is _CT_WAIT_FOR_CLIENT_ seconds.

Cleaner_Client_Header_Timeout (duration)
     Number of seconds to timeout on waiting for client header. This is a timeout for regular cleaning task. The default is _CT_CLIENT_HEADER_ seconds.

Cleaner_Client_Data_Timeout (duration)
     Number of seconds to timeout on waiting for client message body. This is a timeout for regular cleaning task. The default is _CT_CLIENT_DATA_ seconds.

Cleaner_Server_Response_Timeout (duration)
     Number of seconds to timeout on waiting for client to accept answer. This is a timeout for regular cleaning task. The default is _CT_SERVER_RESPONSE_ seconds.

Directory_Browser_Page (string)
     Specify the filename for the directory browser template page. The
     default value is _DIRECTORY_BROWSER_PAGE_}.

Down_Image (string).
     The name of the down arrow image to use in the status page. The default is
     _DOWN_IMAGE_}.

Error_Log_Filename_Prefix (string)
     This is to set the filename prefix for the log file. By default the log filename prefix is the program name (without extension) followed by "_error".

Error_Log_Split_Mode [None/Each_Run/Daily/Monthly]
     It indicates how to split the error logs. Each_Run means that a new log file is used each time the process is started. Daily and Monthly will use a new log file each day or month. The default is _ERROR_LOG_SPLIT_MODE_.

Exchange_Certificate (boolean)
     If set to True it means that the client will be asked to send its certificate to the server. The default value is _EXCHANGE_CERTIFICATE_.

Force_Wait_For_Client_Timeout (duration)
     Number of seconds to timeout on waiting for a client request. This is a timeout for urgent request when resources are missing. The default is _FT_WAIT_FOR_CLIENT_ seconds.

Force_Client_Header_Timeout (duration)
     Number of seconds to timeout on waiting for client header. This is a timeout for urgent request when resources are missing. The default is _FT_CLIENT_HEADER_ seconds.

Force_Client_Data_Timeout (duration)
     Number of seconds to timeout on waiting for client message body. This is a timeout for urgent request when resources are missing. The default is _FT_CLIENT_DATA_ seconds.

Force_Server_Response_Timeout (duration)
     Number of seconds to timeout on waiting for client to accept answer. This is a timeout for urgent request when resources are missing. The default is _FT_SERVER_RESPONSE_ seconds.

Free_Slots_Keep_Alive_Limit (positive)
     This is the minimum number of remaining free slots to enable keep-alive HTTP connections. For heavy-loaded HTTP servers, the Max_Connection parameter should be big enough, and Free_Slots_Keep_Alive_Limit should be about 1-10% of the Max_Connection parameter depending on the duration of the average server response. Longer is the average time to send back a response bigger Free_Slots_Keep_Alive_Limit should be. The default is _KEEP_ALIVE_LIMIT_.

Hotplug_Port (positive)
     This is the hotplug communication port needed to register and un-register an hotplug module. The default value is _HOTPLUG_PORT_.

Key (string)
     Set the RSA key file to be used with the secure servers. The
     default file is _DEFAULT_KEY_}.

Line_Stack_Size (positive)
     The HTTP lines stack size. The stack size must be adjusted for each applications depending on the use of the stack done by the callback procedures. The default is _LINE_STACK_SIZE_.

Log_Extended_Fields (string list)
     Comma separated list of the extended log field names. If this parameter is empty, the HTTP log would be in the apache compartible format, otherwise log file would be in Extended format. For more information see Server Log.

Log_File_Directory (string)
     This is to set the directory where log file must be written. This parameter will be used automatically by AWS.Log if logging facility is enabled. By default log files are written in the current
     directory. The default is _LOG_FILE_DIR_}.

Log_Filename_Prefix (string)
     This is to set the filename prefix for the log file. By default the log filename prefix is the program name (without extension).

Log_Split_Mode [None/Each_Run/Daily/Monthly]
     It indicates how to split the logs. Each_Run means that a new log file is used each time the process is started. Daily and Monthly will use a new log file each day or month. The default is _LOG_SPLIT_MODE_.

Logo_Image (string).
     The name of the logo image to use in the status page. The default is
     _LOGO_IMAGE_}.

Max_Concurrent_Download (positive)
     Control the maximum number of parallel downloads accepted by the download manager. The default value is _MAX_CONCURRENT_DOWNLOAD_.

Max_Connection (positive)
     This is the maximum number of simultaneous connections for the server. This can be used when calling the AWS.Server.Start. The default is _MAX_CONNECT_.

     Note that the total number of threads used by a server is:

          {N = <main server thread> + <max connections> [+ <session>]

     Note: [...] means optional value Add 1 only if the session feature is activated. This is due to the session cleaner task.

MIME_Types (string)
     The name of the file containing the MIME types associations. The default file
     name is _MIME_TYPES_}.

Receive_Timeout (duration)
     Number of seconds to timeout when receiving chunk of data. The default is _RECEIVE_TIMEOUT_ seconds.

Reuse_Address (boolean)
     Set the socket reuse address policy. If set to True the server will be able to bind to a socket that has just been released without the need of waiting. Enabling this feature is not secure and should probably used only for debugging purpose. The default is _REUSE_ADDRESS_.

Security_Mode (string)
     Set the security mode to use for the secure connections. The default
     mode is "_SECURITY_MODE_}". see AWS.Net.SSL.

Send_Buffer_Size (positive)
     This is the socket internal buffer used for sending data to the clients. The default is _SEND_BUFFER_SIZE_.

Send_Timeout (duration)
     Number of seconds to timeout when sending chunk of data. The default is _SEND_TIMEOUT_ seconds.

Server_Host (string)
     The name of the host machine. This can be used if a computer has more than one IP address, it is possible to have two servers at the same port on the same machine, both being binded on different IP addresses.

Server_Name (string)
     The name of the server. This can be used when calling
     AWS.Server.Start. The default is "_SERVER_NAME_}".

Server_Port (integer)
     The port where server will wait for incoming connections requests. This can be used when calling AWS.Server.Start. The default is _SERVER_PORT_.

Session (boolean)
     Whether the session support must be activated or not. The default is _SESSION_.

Session_Name (string)
     The name of the cookie session. This can be used to support sessions for multiple servers embedded into the same executable. The default is "_SESSION_NAME_.

Session_Lifetime (duration)
     Number of seconds to keep session information. After this period a session is obsoleted and will be removed at next cleanup. The default is _SESSION_LIFETIME_ seconds.

Session_Cleanup_Interval (duration)
     Number of seconds between each run of the session cleanup task. This task will remove all session data that have been obsoleted. The default is _SESSION_CLEANUP_INTERVAL_ seconds.

Status_Page (string)
     The name of the status page to used. The default is
     _STATUS_PAGE_}.

Transient_Cleanup_Interval (positive)
     Specify the number of seconds between each run of the cleaner task to remove transient pages. The default value is _TRANSIENT_CLEANUP_INTERVAL_ seconds.

Transient_Lifetime
     Specify the number of seconds to keep a transient page. After this period the transient page is obsoleted and will be removed during next cleanup. The default value is _TRANSIENT_LIFETIME_ seconds.

Up_Image (string)
     The name of the up arrow image to use in the status page. The default is
     _UP_IMAGE_}.

Upload_Directory (string)
     This is to set the directory where upload files must be stored. By default uploaded files are written in the current directory. The
     default is _UPLOAD_DIR_}.

WWW_Root (string)
     This option sets the Web Server root directory. All Web resources are referenced from this root directory. The default value is "_WWW_ROOT_.

Each option value can be retrieved using the AWS.Config unit or set using AWS.Config.Set.

For example to build a server where the port and the maximum number of connection can be changed via a configuration file (either aws.ini or <program_name>.ini):

     {WS   : AWS.Server.HTTP;

Conf : constant AWS.Config.Object := AWS.Config.Get_Current;

Server.Start (WS, Service'Access, Conf);

Session handling
================

AWS provides a way to keep session data while users are browsing. It works by creating transparently a session ID where it is possible to insert, delete and retrieve session data using a standard Ada API (see AWS.Session.). Session data are key/value pair each of them being strings. These sessions data are kept on the server, for client side state management see HTTP state management.

  * First you declare and start an HTTP channel with session enabled:

          {WS : AWS.Server.HTTP;

     Server.Start (WS, Port     => 1234, Callback => Service'Access, Session  => True);

     Here we have built an HTTP channel with a maximum of 3 simultaneous connections using the port 1234. A session ID will be created and sent inside a cookie to the client's browser at the first request. This session ID will be sent back to the server each time the client will ask for a resource to the server.

  * Next, in the Service callback procedure that you have provided you must retrieve the Session ID. As we have seen, the callback procedure has the following prototype:

          {function Service (Request : in AWS.Status.Data) return AWS.Response.Data;}

     The Session ID is kept in the Request object and can be retrieved using:

          {Session_ID  : constant AWS.Session.ID := AWS.Status.Session (Request);}

  * From there it is quite easy to get or set some session data using the provided API. For example:

          {declare

     C : Integer; begin C := AWS.Session.Get (Session_ID, "counter"); C := C + 1; AWS.Session.Set (Session_ID, "counter", C); end;

     This example first get the value (as an Integer) for session data whose key is "counter", increment this counter and then set it back to the new value.

It is also possible to save and restore all session data. It means that the server can be shutdown and launched some time after and all client data are restored as they were at shutdown time. Client will just see nothing. With this feature it is possible to shutdown a server to update its look or because a bug has been fixed for example. It is then possible to restart it keeping the complete Web server context.

HTTP state management
=====================

AWS provides a full implementation of RFC 2109 via the AWS.Cookie package. Using this package you set, get and expire client-side HTTP cookies.

First we set a cookie:

     {declare

Content : AWS.Response.Data; begin AWS.Cookie.Set (Content, Key      => "hello", Value    => "world", Max_Age  => 86400); end;

Here we set the cookie hello with the value world, and we tell the client to expire the cookie 86400 seconds into the future.

Getting the cookie value back is equally simple:

     {declare

Request : AWS.Status.Data --  Assume that this object contain an actual HTTP request. begin Put_Line (AWS.Cookie.Get (Request, "hello")); --  Output 'world' end;

Had the cookie hello not existed, an empty String would've been returned.

In some cases it might be of value to know if a given cookie exists, and for that we have the Exists function available.

     {declare

Request : AWS.Status.Data --  Assume that this object contain an actual HTTP request begin if AWS.Cookie.Exists ("hello") then Put_Line ("The 'hello' cookie exists!"); end if; end;

Note that Exists doesn't care if the cookie contains an actual value or not. If a cookie with no value exists, Exists will return True.

And finally we might wish to tell the client to expire a cookie:

     {declare

Content : AWS.Response.Data; begin AWS.Cookie.Expire (Content, Key  => "hello"); end;

The Cookie package provide Get functions and Set procedures for String, Integer, Float and Boolean types, but since cookies are inherently strings, it's important to understand what happens when the cookie String value can't be converted properly to either Integer, Float or Boolean.

So if either conversion fails or the cookie simply doesn't exist, the following happens:

  * For Integer, the value 0 is returned

  * For Float, the value 0.0 is returned.

  * For Boolean, the value False is returned. Note that only the string ``True'' is True. Everything else is False.

For more information, see AWS.Cookie.

Authentication
==============

AWS supports Basic and Digest authentication. The authentication request can be sent at any time from the callback procedure. For this the AWS.Response.Authenticate message must be returned.

The authentication process is as follow:

 1. Send authentication request

     From the callback routine return an authentication request when needed.

          {function Service (Request : in Status.Data) return Response.Data is

     URI  : constant String := Status.URI (Request); User : constant String := Status.Authorization_Name (Request); begin --  URI starting with "/prot/" are protected if URI (URI'First .. URI'First + 5) = "/prot/" and then User = "" then return Response.Authenticate ("AWS", Response.Basic);

     The first parameter is the Realm, it is just a string that will be displayed (on the authentication dialog box) by the browser to indicate for which resource the authentication is needed.

 2. Check authentication

     When an authentication as been done the callback's request data contain the user and password. Checks the values against an ACL for each protected resources.

          {function Protected_Service

     (Request : in AWS.Status.Data) return AWS.Response.Data is User : constant String := Status.Authorization_Name (Request); Pwd  : constant String := Status.Authorization_Password (Request); begin if User = "xyz" and then Pwd = "azerty" then return ...;

Note that the Basic authentication is not secure at all. The password is sent unencoded by the browser to the server. If security is an issue it is better to use the Digest authentication and/or an SSL server.

File upload
===========

File upload is the way to send a file from the client to the server. To enable file upload on the client side the Web page must contain a FORM with an INPUT tag of type FILE. The FORM must also contain the enctype attribute set to multipart/form-data.

     {<FORM enctype="multipart/form-data" ACTION=/whatever METHOD=POST>

File to process: <INPUT NAME=filename TYPE=FILE> <INPUT TYPE=SUBMIT NAME=go VALUE="Send File"> </FORM>

On the server side, AWS will retrieve the file and put it into the upload directory. AWS add a prefix to the file to ensure that the filename will be unique on the server side. The upload directory can be changed using the configuration options. See Configuration options.

The uploaded files are removed after the user's callback. This is done for security reasons, if files were not removed it would be possible to fill the server hard disk by uploading large files to the server. This means that uploaded files must be specifically handled by the users by either copying or renaming them.

AWS will also setup the form parameters as usual. In the above example there is two parameters (see Form parameters.)

filename
     This variable contains two values, one with the client side name and one with the server side name.

     First value : Parameters.Get (P, "filename")

          The value is the full pathname of the file on the server. (i.e. the upload directory catenated with the prefix and filename).

     Second value : Parameters.Get (P, "filename", 2)

          The value is the simple filename (no path information) of the file on the client side.

go
     The value is "Send File"

Communication
=============

This API is used to do communication between programs using the HTTP GET protocol. It is a very simple API not to be compared with GLADE or SOAP. This communication facility is to be used for simple request or when a light communication support is needed. For more complex communications or to achieve inter-operability with other modules it is certainly a good idea to have a look at the AWS/SOAP support, see SOAP.

In a communication there is a Client and a Server. Here is what is to be done on both sides to have programs talking together.

Communication - client side
---------------------------

On the client side it is quite simple. You just have to send a message using AWS.Communication.Client.Send_Message.

     {function Send_Message

(Server     : in String;
Port       : in Positive;
Name       : in String;
Parameters : in Parameter_Set := Null_Parameter_Set)
return Response.Data;

The message is sent to the specified server using the given port. A message is composed of a name which is a string and a set of parameters. There is a parameter set constructor in AWS.Communication. This function return a response as for any callback procedure.

Communication - server side
---------------------------

On the server side things are a bit more complex but not that difficult. You must instantiate the AWS.Communication.Server generic package by providing a callback procedure. This callback procedure will must handle all kind of message that a client will send.

During instantiation you must also pass a context for the communication server. This context will be passed back to the callback procedure.

     {generic

type T (<>) is limited private; type T_Access is access T;

with function Callback
(Server     : in String;
Name       : in String;
Context    : in T_Access;
Parameters : in Parameter_Set := Null_Parameter_Set)
return Response.Data;

package AWS.Communication.Server is ...

     {A complete example can be found in the demos directory. Look for

com_1.adb and com_2.adb.

Note that this communication API is used by the Hotplug module facility see Hotplug module.

Hotplug module
==============

An Hotplug module is a module that can by dynamically binded to a running server. It is a Web server and the development process is very similar to what we have seen until now see Building an AWS server. The Hotplug module will register itself into a Web server by sending a message using the communication API. The Hotplug module send to the server a regular expression and an URL. The main server will redirect all URL matching the regular expression to the Hotplug module.

Note that the main server will redirect the URL to the first matching regular expression.

Hotplug module - server activation
----------------------------------

The first step is to properly create the main server hotplug module registration file. This file must list all hotplug modules that can register into the main server. Each line have the following format:

     {hotplug_module_name:password:server:port}

hotplug_module_name

     The name of the hotplug module. You can choose any name you want. This name will be use during the registration process and to generate the password.

password

     The MD5 password, see below.

server

     The name of the server where the redirection will be made. This is for security reasons, main server will not permit to redirect requests to any other server.

port

     The port to use for the redirection on server.

You must create a password for each hotplug modules. The generated password depends on the hotplug module name. A tool named aws_password is provided with AWS to generate such password. Usage is simple:

     {$ aws_password <hotplug_module_name> <password>}

Then, after starting the main server you must activate the Hotplug feature:

     {AWS.Server.Hotplug.Activate (WS'Unchecked_Access, 2222, "hotplug_conf.ini");}

hotplug_conf.ini is the hotplug module registration file described above.

Hotplug module - creation
-------------------------

Here is how to create an Hotplug module:

 1. First you create a standard Web server see Building an AWS server.

          {WS : AWS.Server.HTTP

     (3, 1235, False, Hotplug_CB.Hotplug'Access, False);

     Here we have a server listening to the port 1235. This server can be used alone if needed as any Server developed with AWS.

 2. Then you register the Hotplug module to the main server see AWS.Client.Hotplug.

          {Response := AWS.Client.Hotplug.Register

     (Name     => "Hotplug_Module_Demo",
     Password => "my_password",
     Server   => "http://dieppe:2222",
     Regexp   => ".*AWS.*",
     URL      => "http://omsk:1235/");

     The hotplug module Hotplug_Module_Demo must have been declared on the main server, the password and redirection must have been properly recorded too for security reasons see Hotplug module - server activation. This command register Hotplug_Module_Demo into the server running on the machine dieppe and ask it to redirect all URL containing AWS to the server running on machine omsk on port 1235.

 3. When the Hotplug module is stopped, you must unregister it

          {Response := AWS.Client.Hotplug.Unregister

     (Name     => "Hotplug_Module_Demo",
     Password => "my_password",
     Server   => "http://dieppe:2222",
     Regexp   => ".*AWS.*");

     Here we ask to unregister Hotplug_Module_Demo from server dieppe. As for the registration process a proper password must be specified see Hotplug module - server activation.

     {A complete example can be found in the demos directory. Look for

main.adb and hotplug.adb.

Server Push
===========

Server Push is a feature that let the Web Server send continuously data to client's  Web Browser or client applications. The client does not have to reload at periodic time (which is what is called client pull) to have the data updated, each time the server send a piece of data it gets displayed on the client.

To build a push server you need to build an instance of the AWS.Server.Push package. This package takes a set of formal parameters. Here are the step-by-step instructions to build a Push Server:

 1. The data to be sent

     First you must create a type that will contains the data to be sent to client's browser except if it is a standard Ada type. See Client_Output_Type formal parameter.

 2. The data that will be streamed

     This is the representation of the data that will be sent to client's browser. This will be either a String for Web pages or Stream_Element_Array for binary data like pictures. See Stream_Output_Type formal parameter.

 3. The context

     It is often nice to be able to configure each client with different parameters if needed. This can be achieved with the Context data type that will be passed as parameter of the conversion function described below. See Client_Environment formal parameter.

 4. Provides a function to convert from the data type to be sent to the data that will be streamed.

     This is a function that will transform the data described on point 1 above to the form described on point 2 above. See To_Stream_Output formal parameter.

 5. Build the Push Server

     To do so you just need to instantiate AWS.Server.Push with the above declarations.

 6. Registering new clients

     In the standard AWS procedure callback it is possible to register a client if requested. This is done by calling AWS.Server.Push.Register. It is possible to unregister a client using AWS.Server.Push.Unregister. Each client must be identified with a unique client ID. After registering a new client from the callback procedure you must return the AWS.Response.Socket_Taken message. This is very important, it tells the server to not close this socket.

 7. Sending the data

     At this point it is possible to send data to clients. To do so two routines are available.

     AWS.Server.Push.Send_To
          To send a piece of data to a specific client identified by its client ID.

     AWS.Server.Push.Send
          To send a piece of data to all clients registered on this server.

Very large Internet applications should use this feature carefully. A push server keeps a socket reserved for each registered clients and the number of available sockets per process is limited by the OS.

Working with Server sockets
===========================

With AWS is is possible to take out a socket from the server and give it back later. This feature must be used carefully but it gives a lot of flexibility. As the socket is taken away, the connection line (or slot) is released, AWS can then use it to handle other requests.

This can be used to better support heavy loaded servers when some requests need a long time to complete. Long time here means longer than most of the other requests which should be mostly interractives for a Web server. Of course in such a case a keep-alive connection is kept open.

The usage in such a case is to take out the socket and put it in a waiting line. This releases the connection for the server. When the data to prepare the answer is ready you give back the socket to the server.

  * Take a socket from the server

     This first step is done form the callback function. A user instead of replying immediatly decides to take away the socket from the server. The first step is to record the connection socket socket by calling AWS.Status.Socket. The second step is to tell the server to not release this socket by returning AWS.Response.Socket_Taken from the callback function. At this point the server will continue to serve other clients.

     Note that this feature is used by the server push implementation see Server Push.

  * Give back the socket to the server

     Calling AWS.Sever.Give_Back_Socket will register the socket for reuse. This socket will be placed into a spool, next time the server will check for incoming requests it will be picked up.

Server Log
==========

It is possible to have the server activity logged into the file <progname>-Y-M-D.log. To activate the logging you must call the AWS.Server.Log.Start, and it is possible to stop logging by calling AWS.Server.Log.Stop. Note that AWS.Server.Log.Start have a parameter named Auto_Flush to control output buffering. This parameter is False by default. If set to True, the log file will be automatically flushed after each data. If the server logging is not buffered, i.e. Auto_Flush is False, the log can still be flushed by calling the AWS.Server.Log.Flush routine. See AWS.Log, for more information especially about the way rotating logs can be setup. Using this feature it is possible to have automatic split of the log file each day, each month or at every run. See AWS.Log spec. This is very useful to avoid having very big log files.

The log format depend on Log_Extended_Fields configuration parameter. If this parameter is empty, the HTTP log would have fixed apache compartible format:

     {<client IP> - <auth name> - [<date and time>] "<request>" <status code> <size>

For example:

100.99.12.1 -  - [22/Nov/2000:11:44:14] "GET /whatever HTTP/1.1" 200 1789

If the extended fields list is not empty, the log file format would have user defined fields set:

     {#Version: 1.0

#Date: 2006-01-09 00:00:01 #Fields: date time c-ip cs-method cs-uri cs-version sc-status sc-bytes 2006-01-09 00:34:23 100.99.12.1 GET /foo/bar.html HTTP/1.1 200 30

Fields in the comma separated Log_Extended_Fields list could be:

date
     Date at which transaction completed

time
     Time at which transaction completed

time-taken
     Time taken for transaction to complete in seconds

c-ip
     Client side connected IP address

c-port
     Client side connected port

s-ip
     Server side connected IP address

s-port
     Server side connected port

cs-method
     HTTP request method

cs-username
     Client authentication username

cs-version
     Client supported HTTP version

cs-uri
     Request URI

cs-uri-stem
     Stem portion alone of URI (omitting query)

cs-uri-query
     Query portion alone of URI

sc-status
     Responce status code

sc-bytes
     Length of response message body

cs(<header>)
     Any header field name sent from client to server

sc(<header>)
     Any header field name sent from server to client

x-<appfield>
     Any application defined field name

AWS also support error log files. If activated every internal error detected by AWS will gets logged into this special file. Log file for errors would be in simple apache compartible format. See AWS.Server.Log.Start_Error and AWS.Server.Log.Stop_Error.

For the full set of routines supporting the log facility see AWS.Server.Log .

Secure server
=============

It is not much difficult to use a secure server (HTTPS) than a standard one. Here we describe only what is specific to an HTTPS server.

Before going further you must check that AWS has been configured with SSL support. see Building. You must also have installed the OpenSSL library on your system. If this is done, you can continue reading this section.

Initialization
--------------

A server is configured as using the HTTPS protocol at the time it is started. The only thing to do is to set the Start's Security parameter to True. This will start a server and activate the SSL layer by default. A secure server must use a valid certificate, the default one
is _DEFAULT_CERTIFICATE_}. This certificate has been
created by the openssl tool and is valid until year 2008. Yet, this
certificate has not been signed. To build a secure server user's can
rely on, you must have a valid certificate signed by one of the
Certificate Authorities.

The certificate to be used must be specified before starting the
secure server with AWS.Server.Set_Security.

     {AWS.Server.Set_Security (WS, Certificate_Filename => "/xyz/aws.pem");}

Creating a test certificate
---------------------------

The goal here is not to replace the OpenSSL documentation but just to present one way to create a certificate for an HTTPS test server.

The RSA key

          {$ openssl genrsa -rand <filename> -out ca-key.pem}

     Filename must be point to any file, this is used to initialized the random seed.

The Certificate

          {$ openssl req -new -x509 -days 730 -key ca-key.pem -out ca-cert.pem}

Create a single self contained file

          {$ cat ca-key.pem ca-cert.pem > aws.pem}

A this point you can use aws.pem with your server.

Protocol
--------

There are different security options, either SSLv2, SSLv3 or TLSv1. SSLv2 and SSLv3 are supported by most if not all Web browsers. These are the default protocol used by AWS.

TLSv1 is not supported at this point.

Unexpected exception handler
============================

When AWS detects an internal problem, it calls a specific handler. This handler can be used to log the error, send an alert message or build the answer to be sent back to the client's browser.

Here is the spec for this handler:

     {type Unexpected_Exception_Handler is access

procedure (E      : in     Ada.Exceptions.Exception_Occurrence;
Log    : in out AWS.Log.Object;
Error  : in     Data;
Answer : in out Response.Data);

The handler can be called in two modes:

Non fatal error (Error.Fatal is False)

     In this case AWS will continue working without problem. A bug has been detected but it was not fatal to the thread (slot in AWS's terminology) handling. In this case it is possible to send back an application level message to the client's browser. For that you just have to fill the unexpected handler's ANSWER parameter with the right response message. The ERROR parameter receive information about the problem, see AWS.Exceptions.

Fatal error (Error.Fatal is True)

     In this case AWS will continue working but a thread (slot number ERROR.SLOT in AWS's terminology) will be killed. It means that AWS will have lost one the simultaneous connection handler. The server will continue working unless it was the last slot handler available. Note that a Fatal error means an AWS internal bug and it should be reported if possible. In this mode there is no way to send back an answer to the client's browser and ERROR value must be ignored.

The default handler for unexpected exceptions send a message to standard error for fatal errors. For non fatal errors it log a message (if the error log is activated for the server) and send back a message back to the client. The message is either a built-in one or, if present in the server's directory, the content of the 500.tmplt file. This templates can used the following tags:

AUTH_MODE
     The authorization mode (Either NONE, BASIC or DIGEST).

EXCEPTION
     Exception information with traceback if activated.

HTTP_VERSION
     Either HTTP/1.0 or HTTP/1.1

METHOD
     The request method (Either GET, HEAD, POST or PUT)

PAYLOAD
     The full XML payload for SOAP request.

PEERNAME
     The IP address of the client

SOAP_ACTION
     Either True or False. Set to True for a SOAP request.

URI
     The complete URI

For more information see AWS.Server and see AWS.Exceptions.

Socket log
==========

To ease AWS applications debugging it is possible to log all data sent/received to/from the sockets. For this you need to call the AWS.Net.Log.Start routine by passing a write procedure callback. You have to create such procedure or use one read-to-use provided in AWS.Net.Log.Callbacks package.

For more information see AWS.Net.Log and see AWS.Net.Log.Callbacks.

Client side
===========

AWS is not only a server it also implement the HTTP and HTTPS protocol from the client side. For example with AWS it is possible to get a Web page content using the AWS.Client API, see AWS.Client.

It also support client Keep-Alive connections. It is then possible to request many URI from the same server using the same connection (i.e. the same sockets).

AWS client API also support proxy, proxy authentication and Web server authentication. Only basic (and not digest) authentication is supported at this time.

Let's say that you want to retrieve the contrib.html Web page from Pascal Obry's homepage which is http://perso.wanadoo.fr/pascal.obry. The code to do so is:

     {Data := Client.Get

(URL => "http://perso.wanadoo.fr/pascal.obry/contrib.html");

From there you can ask for the result's content type:

     {if Response.Content_Type (Data) = "text/html" then

... end if;

Or using the MIME types defined in AWS.MIME unit:

     {if Response.Content_Type (Data) = MIME.Text_HTML then

... end if;

And display the content if it is some kind of text data:

     {Text_IO.Put_Line (Response.Message_Body (Data));}

If the content is some kind of binary data (executable, PNG image, Zip archive...), then it is possible to write the result to a file for example. Look at the agent program in the demos directory.

If the Web page is protected and you must pass the request through an authenticating proxy, the call will becomes:

     {Data := Client.Get

(URL        => "http://www.mydomain.net/protected/index.html"
User       => "me",
Pwd        => "mypwd",
Proxy      => "192.168.67.1",
Proxy_User => "puser",
Proxy_Pwd  => "ppwd");

The client upload protocol is implemented. Using AWS.Client.Upload it is possible to send a file to a server which support the file upload protocol.

High level services
*******************

Here you will find a description of high level services. These services are ready to use with AWS and can be used together with user's callbacks.

Refer to the Ada spec for a complete API and usage description.

Directory browser
=================

This service will help building a Web directory browser. It has a lot of options to sort directory entries and is based on the templates interface see AWS.Templates. This means that you can use the default directory template or provide your own.

see AWS.Services.Directory for complete spec and services descriptions.

Dispatchers
===========

In many AWS applications it is needed to check the URI to give the right answer. This means that part of the application is a big if/elsif procedure. Also, in standard callback it is not possible to have user data. Both of these restrictions are addressed with the Dispatchers facilities.

Working with a dispatcher is quite easy:

 1. Create a new dispatcher by inheriting from the service you want to build.

 2. Register a set of action based on rules (strings, regular expressions depending on the service)

Callback dispatcher
-------------------

This is a wrapper around the standard callback procedure. It is needed to mix dispatcher based callback and access to procedure callback. Note that it is not in the AWS.Services.Dispatchers hierarchy but in AWS.Dispatchers.Callback because this is a basic service needed for the server itself. It is referenced here for documentation purpose but an AWS server can be built with using it.

see AWS.Dispatchers.Callback for complete spec description.

Method dispatcher
-----------------

This is a dispatcher based on the request method. A different callback procedure can be registered for the supported request methods: GET, POST, PUT, HEAD.

see AWS.Services.Dispatchers.Method for complete spec description.

URI dispatcher
--------------

This is a dispatcher based on the request resource. A different callback procedure can be registered for specific resources. The resource is described either by its full name (string) or a regular expression.

see AWS.Services.Dispatchers.URI for complete spec description.

Virtual host dispatcher
-----------------------

This is a dispatcher based on the host name. A different callback procedure can be registered for specific host. This is also known as virtual hosting.

The same computer can be registered into the DNS with different names. So all names point to the same machine. But in fact you want each name to be seen as a different Web server. This is called virtual hosting. This service will just do that, call different callback procedures or redirect to some machine/port based on the host name in the client's request.

see AWS.Services.Dispatchers.Virtual_Host for complete spec description.

Transient pages dispatcher
--------------------------

This is a dispatcher that calls a user's callback and if the resource requested is not found (i.e. the user's callback returns status code 404) it checks if this resource is known as a transient page. see Transient Pages.

Timer dispatcher
----------------

A timer dispatcher can be used to call different callback routines depending on the current date and time. Such dispatcher is composed of a set of Period activated. When the current date and time is inside a Period the corresponding callback is called. A Period can eventually be repeated. Here are the different kind of Period supported by AWS:

Once

     A unique period in time. The boundaries are fully described using a year, month, day, hour, minute and second.

Yearly

     A period that repeats each year. The boundaries are described using a month, day, hour, minute and second.

Monthly

     A period that repeats each month. The boundaries are described using a day, hour, minute and second.

Weekly

     A period that repeats each week. The boundaries are described using a day name, hour, minute and second.

Daily

     A period that repeats each day. The boundaries are described using an hour, minute and second.

Hourly

     A period that repeats each hour. The boundaries are described using a minute and second.

Minutely

     A period that repeats each minute. The boundaries are described using a second.

Linker dispatcher
-----------------

A dispatcher that can be used to chain two dispatchers. The response of the first dispatcher is returned except if it is a 404 (Not Found) error. In this case, the response of the second dispatcher is returned.

SOAP dispatcher
---------------

AWS provides also a SOAP specific dispatcher. This is a way to automatically route HTTP requests or SOAP requests to different callback routines.

see SOAP helpers for more information.

see SOAP.Dispatchers.Callback for complete spec description.

Static Page server
==================

This service is a ready to use static page server callback. Using it is possible to build a simple static page server, as simple as:

     {with AWS.Server;

with AWS.Services.Page_Server;

procedure WPS is WS : AWS.Server.HTTP; begin AWS.Server.Start (WS, "Simple Page Server demo", Port           => 8080, Callback       => AWS.Services.Page_Server.Callback'Access, Max_Connection => 5);

AWS.Server.Wait (AWS.Server.Q_Key_Pressed);

AWS.Server.Shutdown (WS); end WPS;

Build this program and launch it, it will server HTML pages and images in the current directory.

It is possible to activate the directory browsing facility of this simple page server. This is not activated by default. This feature is based on the directory browsing service see Directory browser.

Note that this service uses two template files:

aws_directory.thtml

     The template page used for directory browsing. See AWS.Services.Directory for a full description of this template usage.

404.thtml

     The Web page returned if the requested page is not found. This is a template with a single tag variable named PAGE. It will be replaced by the ressource which was not found.

     Note that on Microsoft IE this page will be displayed only if the total page size is bigger than 512 bytes or it includes at least one image.

see AWS.Services.Page_Server for a complete spec description.

Transient Pages
===============

A transient page is a resource that has a certain life time on the server. After this time the resource will be released and will not be accessible anymore.

Sometimes you want to reference, in a Web page, a resource that is built in memory by the server. This resource can be requested by the client (by clicking on the corresponding link) or not, in both cases the page must be released after a certain amount of time to free the associated memory.

This is exactly what the transient pages high level service do automatically. Each transient page must be registered into the service, a specific routine named Get_URI can be used to create a unique URI on this server. see AWS.Services.Transient_Pages.

A transient pages dispatcher can be used to build a transient pages aware server. see Transient pages dispatcher.

Split pages
===========

It not not very convenient to send back a Web page with a large table. In such a case it is better to split the table in chunks (20 lines or so) and to send only the first page. This page reference the next pages and can also contains an index of the pages.

The AWS's split page feature can automatically do that for you. Given template Translate_Table or Translate_Set and the max line per page it returns the first page and create a set of transient pages for all other pages. A set of template tags are used to reference the previous and next page and also to build the page index.

There is different ways to split a set of pages and ready-to-use splitters are available:

Alpha
     Split in (at most) 28 pages, one for empty fields, one for all fields that start with a digit, and one for each different initial letter. see AWS.Services.Split_Pages.Alpha.

Alpha.Bounded
     Same as the alpha splitter, but pages larger than a Max_Per_Page value are further splitted. A secondary index is generated that gives the various pages for a given letter. see AWS.Services.Split_Pages.Alpha.Bounded.

Uniform
     Split in pages of length Max_Per_Page (except the last one). This corresponds to the default service in Split_Pages package. see AWS.Services.Split_Pages.Uniform.

Uniform.Alpha
     Same as the uniform splitter, but builds in addition an alphabetical secondary index from a key field. see AWS.Services.Split_Pages.Uniform.Alpha.

Uniform.Overlapping
     Same as the uniform splitter, but pages (except the first one) repeat Overlap lines from the previous page in addition to the Max_Per_Page lines. see AWS.Services.Split_Pages.Uniform.Overlapping.

Using the spliter abstract interface it is possible to build a customized splitter algorithm. see AWS.Services.Split_Pages.

Download Manager
================

A server that need to handle lot of large downloads can run out of connection to answer the standard Web pages. A solution is to increase the number of simultaneous connections, but this is not really efficient as a task is created for each connection and does not ensure that all the connections will be used for the downloads anyway.

The download manager can be used for that, and provides the following feature:

  * use a single task for all downloads

  * can be configured to limit the number of simultaneous connections

  * downloads past this limit are queued

  * send messages to the client with the position in the waiting line

  * send messages to the client when the download is about to start

The server must be configured to use dispatchers (standard callbacks are not supported, note that it is possible to create a dispatcher for standard callbacks. see AWS.Dispatchers.Callback).

To start the download manager you need to pass the main server dispatcher object. The start routine will return a new dispatcher, linked with the download server specific dispatcher, that must be used to start the standard Web server. See comment in see AWS.Services.Download.

To queue a download request in the download manager you just need to create a stream object (can be any kind of stream, see AWS.Resources.Streams.*) for the resource to download.

The download manager needs two templates files:

aws_download_manager_waiting.thtml

     This template is used for sending a message to the client when the request is on the waiting line. The tags defined in this template file are:

     NAME
          the name of the resource to download (the filename), this is the default filename used for the client side save dialog.

     RES_URI
          the URI used to access the resource.

     POSITION
          the position in the waiting line (not counting the current served clients).

aws_download_manager_start.thtml

     This template is used for sending a message to the client when the download is about to start (the request is out of the waiting line). The tags defined in this template file are:

     NAME
          as above

     RES_URI
          as above

It is important to note that those templates must be reloaded periodically. The best way to do that in the context of an HTML document is to use a meta-tag. For example to refresh the page every two seconds:

     <meta http-equiv="refresh" content="2">

The templates could look like:

aws_download_manager_waiting.thtml

     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
     "http://www.w3.org/TR/html4/strict.dtd">
     <html>
     <head>
     <meta http-equiv="refresh" content="2">
     <title>Download Manager - waiting</title>
     </head>
     <body>
     <p>Waiting for downloading @_NAME_@
     <p>Position in the waiting line @_POSITION_@
     </body>
     </html>

aws_download_manager_start.thtml

     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
     "http://www.w3.org/TR/html4/strict.dtd">
     <html>
     <head>
     <meta http-equiv="refresh" content="2">
     <title>Download Manager - waiting</title>
     </head>
     <body>
     <p>Waiting for downloading @_NAME_@
     <p>The download will start in a moment
     </body>
     </html>

Web Elements
============

AWS provides some components to help creating nice looking Web interfaces. It is possible to browse those Web Elements using the web_elements demo. Just launch this Web application from the demos directory and turn your Web browser to http://localhost:2400.

Currently AWS provides:

  * Notebooks (based on CSS)

  * CSS Menu

  * Rounded boxes

  * Ajax

All of them are based on templates to be easily reused in other applications. The three first are best described by the Web Elements demos as they are 100% design. The Ajax one is a bit more complex, we will present its use in the following section.

Installation
------------

To ease integration we have used the following design:

  * Sub-directories found in the AWS's web_elements directory are self contained. The content must be copied into the project. Note that the icons and javascripts directories contain the icons and javascripts code shared by all web elements and must also be copied, see below.

  * Each graphic elements (icons) is referenced into the templates with the alias /we_icons/<icon_name>. So users must provide the right alias ("/we_icons/") in the  Web server.

  * Each JavaScripts code is referenced into the templates with the alias /we_js/<script>. So users must provide the right alias ("/we_js/") in the  Web server.

Ajax
----

First of all, Ajax stand for Asynchronous JavaScript language and XML, and is not well defined at the moment. Ajax is on one side able to send HTTP requests to the Web server and on the other side able to manipulate directly the Web browser's DOM tree. On the DOM it can add, remove or replace XML nodes. So, it is possible to change the content of a Web page without reloading it from the server.

Most importantly, Ajax changes the way Web applications are thought from page based to event based.

As implemented into AWS, Ajax support comes as a set of JavaScript templates. Using those templates there is no need to know JavaScript (except for the JavaScript event names) and it makes Ajax programming lot easier. Two actions are provided, one for replacing another for clearing part of the web page content.

Steps to do Ajax
................

What are the steps to do Ajax ?

Remember, do not think about the Web page but about a specific widget (HTML fragments) with the associated event and action.

 1. Include the AWS/Ajax support file

     This is the AWS/Ajax runtime, it contains JavaScript code needed for the AWS/Ajax support.

 2. Create the Web widgets/forms

     There is nothing special here, use your favorite Web designer tool.

 3. Create Web area

     Using some HTML <div> tags we create areas where we will place HTML fragments later. For example when clicking on a button (described above) in our Web interface we want to display a new form in this area.

 4. Name the widgets/forms/area using id="name" attribute

     Give a different name to the widgets using id="name". This name will be later used to identify the widgets on which the envent and corresponding action must be placed. We do not want to clutter the Web design with JavaScript code like onclick="dothis()" or onchange="dothat()".

 5. Add the proper event/action to the widgets using the AWS/Ajax templates

     This is the interresting part. At this point we link events/actions to the widgets and specify in which area the results sent by the server will be placed.

This is not the only way to do Ajax, we just presented here a simple approach that works well with the AWS/Ajax templates.

Basic Ajax support
..................

This section describes the AWS/Ajax support where the answer from the server is an HTML fragment. This basic support is designed to be used for migration of a Web server to Ajax. For new applications, it is worth considering using the XML based Ajax support, see XML based Ajax.

Let's have a very simple example:

  * The AWS/Ajax runtime support

          @@INCLUDE@@ aws.tjs

     Must be included in every Web pages into the <head> tag.

  * The widget: a button

          <input id="clickme" type="button" value="Clik Me">

  * The result area: a div

          <div id="placeholder">... result here ...</div>

  * The AWS/Ajax

          @@INCLUDE@@ aws_action_replace.tjs onclick clickme placeholder

     Basically it places an onclick attribute (the event) in the HTML <input> identified as clickme (the action) above. Here is what happen when the button is clicked:

       * send the "/onclick$clickme" HTTP request to the server

       * asynchronously wait for the answer, when received place the message body into the <div> placeholder.

On the server side the code would look like this:

function Callback (Request : in Status.Data) return Response.Data is
URI : constant String := Status.URI (Request);
begin
if URI = "/clickme" then
return Response.Build (MIME.Text_HTML, "you click me!");
...

So when the button is clicked the string "you click me!" will replace the "... result here ..." string of the place holder div above.

This is a simple and very limited example as there is no parameter passed to the HTTP request. In real Web applications it is necessary to send a context with the request. This can be either the value of other widgets or all values of widgets' form.

References to widgets or forms can be passed to the aws_action_replace.tjs template starting with the 5th parameter.

<input id="field" type="text" value="default value">

...

@@INCLUDE@@ aws_action_replace.tjs (onclick clickme placeholder 5=>field)

or

<form id="small_form" name="small_form">
...
</form>

@@INCLUDE@@ aws_action_replace.tjs (onclick clickme placeholder 5=>small_form)

Note that the onclick event is only one of the possible JavaScript event on a button. It is possible to used any supported event, for example on an HTML <select> widget it is common to map the action to the onchange event.

AWS also provides support for clearing an area or a widget content (like an input).

     @@INCLUDE@@ aws_action_clear.tjs (onclick, clear, field)

This simple action adds the onclick event to the clear button to erase the content of the field widget.

XML based Ajax
..............

In many cases you'll like to update and/or clear multiple areas in your Web interface. With the templates above only a single action is possible. AWS provides support for XML based answers. In this XML documents it is possible to:

  * replace an area with a new content

          <replace id="item_id">new text</replace>

  * clear an area

          <clear id="item_id"/>

  * add an item into a select widget

     <select action="add" id="item_id"
     option_value="value" option_content="content"/>

  * remove an item from a select widget

          <select action="delete" id="item_id" option_value="value"/>

  * select a specific item in a select widget

          <select action="select" id="item_id" option_value="value"/>

  * clear a select widget (remove all items)

          <select action="clear" id="item_id"/>

  * select a radio button

          <radio action="select" id="item_id"/>

  * check a checkbox

          <check action="select" id="item_id"/>

  * clear a checkbox

          <check action="clear" id="item_id"/>

  * call another URL

     <get url="http://thishost/action">
     <parameters value="name=Ajax"/>
     <field id="input1"/>
     </get>

     This will send the following request:

          http://thishost/action?name=Ajax&input1=<val_input1>

     Where val_input1 is the current value of the input1 input widget. The result must be an XML/Ajax document that will be parsed.

  * make a list sortable

     <make_sortable>
     <list id="firstlist"/>
     <list id="secondlist"/>
     </make_sortable>

     Here firstlist and secondlist are id of UL elements. It is possible to specified as many list id as needed. A drag and drop is then possible for all elements in those lists. It is then possible to reference such list by passing the list id as a field to the template. Items on those list will be serialized and passed to the AWS callback. Note that for the serialization to work properly, each LI elements must be given the id of the list and then the value we want to pass.

     <ul id="firstlist">
     <li id="firstlist_red">Red</li>
     <li id="firstlist_green">Green</li>
     <li id="firstlist_blue">Blue</li>
     </ul>

     The serialization will send each value on this list using a multi-valued parameter named firstlist[].

          http://server?firstlist[]=red&firstlist[]=green&firstlist[]=blue

  * make a list not sortable

     <destroy_sortable>
     <list id="firstlist"/>
     <list id="secondlist"/>
     </destroy_sortable>

     Remove the sortable properly from the specified lists.

  * redirect to another URL

          <location url="http://thishost/go_there"/>

     Redirect the browser to the specified URL.

  * refresh the current page

          <refresh/>

     Refresh the current page as if the Web Browser refresh button was pressed.

  * add a CSS style to a given node

     <apply_style id="node_id">
     <attribute id="display" value="none"/>
     </apply_style>

     Add the CSS style display:none to the node_id element. It is possible to specify multiple attributes if needed.

  * make an entry disabled or enabled

          <disabled id="item_id" value="true/false"/>

  * make an entry read-only or writable

          <read_only id="item_id" value="true/false"/>

  * reset a form

          <reset id="form_id"/>

Here is an example of such XML document:

<response>
<replace id="xml_status_bar">Fill Widgets...</replace>
<replace id="text1">Response from XML</replace>
<replace id="text2">Another response for text2</replace>
<replace id="input1">tag is input1</replace>
<replace id="input2">tag is input2</replace>
<select action="add" id="xmlsel" option_value="one" option_content="1"/>
<select action="add" id="xmlsel" option_value="two" option_content="2"/>
<select action="add" id="xmlsel" option_value="three" option_content="3"/>
<select action="select" id="xmlsel" option_value="two"/>
<radio action="select" id="radio1"/>
<check action="select" id="check1"/>
<check action="select" id="check3"/>
<check action="clear" id="check2"/>
</response>

To register an Ajax action to a specific tag id a macro can be used. It is named JS_ACTION and defined in ajax_api.tjs. The usage is similar to what is described in the previous section (see Basic Ajax support) except that in this case we use a macron instead of an include file and we do not have to pass the placeholder.

Let's revisit the first example above to use the XML Ajax support.

  * The AWS/Ajax runtime support

          @@INCLUDE@@ aws.tjs

     Must be included in every Web pages into the <head> tag.

  * The AWS/Ajax API

          @@INCLUDE@@ ajax_api.tjs

     Must be included at least once during an application life-time. It gives access to the JS_ACTION macro.

  * The widget: a button

          <input id="clickme" type="button" value="Clik Me">

  * The result area: a div

          <div id="placeholder">... result here ...</div>

  * The AWS/Ajax

          @_JS_ACTION(onclick, clickme)_@

     Basically it places an onclick attribute (the event) in the HTML <input> identified as clickme (the action) above. Here is what happen when the button is clicked:

       * send the "/onclick$clickme" HTTP request to the server

       * asynchronously wait for the XML answer, when received parse the answer and perform the actions according to the XML content.

To set the placeholder with "new text", the XML document returned by the server must be:

<response>
<replace id="placeholder">new text</replace>
</response>

If we want also to clear the input field named field and to select the radio button named radio1 we must return:

<response>
<replace id="placeholder">new text</replace>
<clear id="field"/>
<radio action="select" id="radio1"/>
</response>

This is by far the most flexible solution as it is possible to return, from the server, a structured answer.

A final comment, if the text returned by the server to replace a specific area is an HTML fragment, the content must be placed into a CDATA tag:

<response>
<replace id="item_id">
<![CDATA[ HTML CODE HERE ]]>
</replace>
</response>

Advanced Ajax
.............

Finally, if this is not enough because you need to use some specific JavaScript code, AWS provides a macro named BIND_JS to add an event to a specific widget, the action being the name of a JavaScript routine.

This macro together with the aws_func_replace.tjs, aws_func_clear.tjs templates and the JS_ACTION macro can be used to chain multiple actions. Those templates are the function body used by the corresponding templates aws_action_replace.tjs, aws_action_clear.tjs.

Let say you want to clear a widget, change the content of another one and calling one of your specific JavaScript routine when clicking on a button. It is not possible to have mutiple onclick events on the same widget, the solution is the following:

  * Create the JavaScript routine to do the job

     For this in the the body of the clear_replace() JavaScript routine we place:

     function clear_replace()

     { @@INCLUDE@@ aws_func_replace.tjs (clickme placeholder 4=>field)
     @@INCLUDE@@ aws_func_clear.tjs (area)
     call_this_routine();

     }

     Then to add the event on the widget:

          @_BIND_JS(onclick, clickme clear_replace)_@

Furthermore, it is possible to pass (as the parameter number 20) a routine to call after a specific action to all templates and to the JS_ACTION macro. This is another way to chain multiple actions for a single event.

Note that all AWS/Ajax templates and the ajax_api.tjs file have a set of comments at the start explaining in details the usage of each parameter.

Web Blocks
==========

The AWS.Services.Web_Block hierarchy contains an API useful for keeping context on Web pages. It has been designed to be able to split a Web application into a set of independent blocks that can be put together in the same Web page. The context is then useful as it is passed and known by each individual block. Note that this is different than the session as a session is global to the current Web browser whereas the context can be different for each individual web pages opened.

Instead of parsing a whole page using AWS.Templates API the web blocks are registered independently using AWS.Services.Web_Block.Registry. The block is registered together with its templates and a callback to use to get user's data for this specific block with the given context.

So using this API, instead of having a set of callbacks returning an AWS.Response.Data and where the final rendering is to be done by the client code, we have a set of callbacks that returns a Translate_Set. The client just have to fill the set with the data corresponding to the actual request and possibly using the context. The final rendering is done by the provided services in Web_Block.Registry.

Note that all Web pages must also be registered into the registry to ensure that the context identification is properly kept. The context identification is injected into the Web pages transparently for the end-user when using Ajax.

Web Block example
-----------------

Let's have a simple example, a page containing a single block with a tag (@_COUNTER_@) which is incremented by one each time it is used. The code can be found in demos/web_block.

First create the following HTML fragment and place it into counter.thtml.

     <p>@_COUNTER_@</p>

Then create the main page and place it into page.thtml. The important part is the @_CTX_WB_@ tag which is passed to the link. This tag is the context identifier, it must be passed to each request. Note that this is automatically done when using the Ajax framework (see Web Block and Ajax).

<html>
<head>
<title>Main Page</title>
</head>
<body>
<p>This is the main page, bellow is a simple counter</p>
<p>@_COUNTER_@</p>
<a href="/?CTX_WB=@_CTX_WB_@>Next</a>
</body>
</html>

The Web_Callbacks package contains the application callbacks.

with AWS.Response;
with AWS.Status;
with AWS.Templates;
with AWS.Services.Web_Block.Context;

package Web_Callbacks is

use AWS;
use AWS.Services;

function Main (Request : in Status.Data) return Response.Data;
--  Main callback which handle the home page

procedure Counter
(Request      : in              Status.Data;
Context      : not null access Web_Block.Context.Object;
Translations : in out          Templates.Translate_Set);
--  The callback handling the counter web block

end Web_Callbacks;

Last part is to actually implement the Counter callback. Here is a possible implementation making use of the context to keep the counter state.

with AWS.Utils;
with AWS.Messages;
with AWS.MIME;
with AWS.Services.Web_Block.Registry;

package body Web_Callbacks is

-------------
-- Counter --
-------------

procedure Counter
(Request      : in              Status.Data;
Context      : not null access Web_Block.Context.Object;
Translations : in out          Templates.Translate_Set)
is
N : Natural := 0;
begin
if Context.Exist ("N") then
N := Natural'Value (Context.Get_Value ("N"));
end if;

N := N + 1;
Context.Set_Value ("N", Utils.Image (N));

Templates.Insert
(Translations,
AWS.Templates.Assoc ("COUNTER", N));
end Counter;

----------
-- Main --
----------

function Main (Request : in Status.Data) return Response.Data is
URI : constant String := Status.URI (Request);
begin
return Web_Block.Registry.Build
(Key          => URI,
Request      => Request,
Translations => Set);
end Main;

end Web_Callbacks;

Finally, we write the main procedure:

with Ada.Text_IO;

with AWS.Server;
with AWS.Services.Web_Block.Registry;

with Web_Callbacks;

procedure Web_Block is

use Ada;
use AWS;
use AWS.Services;

HTTP : AWS.Server.HTTP;

begin
--  First we register the main page and the counter block

Services.Web_Block.Registry.Register
("/", "page.thtml", null);

Services.Web_Block.Registry.Register
("COUNTER", "counter.thtml",
Web_Callbacks.Counter'Access, Context_Required => True);

--  Then we just start the server

Server.Start (HTTP, "web_block", Web_Callbacks.Main'Access);

Text_IO.Put_Line ("Press Q to terminate.");

Server.Wait (Server.Q_Key_Pressed);

Server.Shutdown (HTTP);
end Web_Block;

Compile and run the server. Then connect to the server and click on next. The counter will be incremented by one each time.

Web Block and Ajax
------------------

The Web Block framework has really been designed to be used with Ajax. It is the only way to gain the full power of the Web Block framework.

For the complete code, see demos/web_block_ajax.

When using Ajax it is not needed to explicitly pass the context identification to every link. This is done automatically by the framework. So the main page will look like this:

@@INCLUDE@@ ../../web_elements/javascripts/ajax_api.tjs
<html>
<head>
<title>Main Page</title>
@@INCLUDE@@ ../../web_elements/javascripts/aws.tjs
</head>
<body>
<p>This is the main page, bellow is a simple counter</p>
@_WIDGET_COUNTER_@
</body>
</html>

The counter widget is on widget_counter.thtml:

<!-- implementation of a simple counter widget -->
<p><div id="counter">@_COUNTER_@</div></p>
<a id="next" href="/">Next</a>
@_JS_ACTION(onclick, next)_@

For the Ajax part, see Ajax.

We now have one more register call for registering the next button Ajax callback, and a callback named Widget_Counter for displaying the block:

Services.Web_Block.Registry.Register
("WIDGET_COUNTER", "widget_counter.thtml",
Web_Callbacks.Widget_Counter'Access);

Services.Web_Block.Registry.Register
("/onclick$next", "r_widget_counter.txml",
Web_Callbacks.Onclick_Next'Access,
Content_Type     => MIME.Text_XML,
Context_Required => True);

The next Ajax button is using an XML based response which is defined in r_widget_counter.txml:

<response>
<replace id="counter">@_COUNTER_@</replace>
</response>

The Widget_Counter callbacks just have to set the COUNTER tag variable to the corresponding value. This is used to display the block. The Ajax callback Onclick_Next has to increment the counter and set the COUNTER tag variable, a simple implementation is:

procedure Onclick_Next
(Request      : in              Status.Data;
Context      : not null access Web_Block.Context.Object;
Translations : in out          Templates.Translate_Set)
is
N : Natural := 0;
begin
if Context.Exist ("N") then
N := Natural'Value (Context.Get_Value ("N"));
end if;

N := N + 1;

Context.Set_Value ("N", Utils.Image (N));

Templates.Insert
(Translations, Templates.Assoc ("COUNTER", N));
end Onclick_Next;

The framework will then call Onclick_Next when pressing the Next button. This routine increments N by one sending back a response based on r_widget_counter.txml. Finally, the client browser will parse this XML response and do the corresponding actions.

Web Block and templates2ada
---------------------------

For the complete code, see demos/web_block_ajax_templates.

It is possible to use the Templates_Parser's templates2ada tool for generating the callbacks register calls. This ensures that all tags on the application Web Pages have a corresponding callback.

The code is almost identical to the standard Ajax example above. The main difference is that we need to use a naming convention for the blocks. This way we can generate automatically the corresponding callbacks using a template. A common convention is to add LAZY_ as prefix for the name of the blocks. With this convention the main page template is:

@@INCLUDE@@ ../../web_elements/javascripts/ajax_api.tjs
<html>
<head>
<title>Main Page</title>
@@INCLUDE@@ ../../web_elements/javascripts/aws.tjs
</head>
<body>
<p>This is the main page, bellow is a simple counter</p>
@_LAZY_WIDGET_COUNTER_@
</body>
</html>

We need also modify the standard templates.tads as distributed with the Templates_Parser. Here is the interesting part:

@@SET@@ PACKAGE = WBlocks

...

with AWS.MIME;
with AWS.Services.Web_Block.Registry;
with Web_Callbacks;

@@TABLE@@
with @_PACKAGE_@.@_CAPITALIZE:REPLACE_ALL(\./_):BASENAME_@;
@@END_TABLE@@

package body @_PACKAGE_@ is

use AWS;

package body Lazy is

--------------
-- Register --
--------------

procedure Register is
use AWS.Services;
begin
--  Register blocks
@@TABLE@@
@@IF@@ @_UPPER:SLICE(1..5):VARIABLE_LIST_@ = "LAZY_"
Web_Block.Registry.Register
("@_VARIABLE_LIST_@",
"@_LOWER:REPLACE_ALL(LAZY_/):VARIABLE_LIST_@.thtml",
Web_Callbacks.@_CAPITALIZE:REPLACE_ALL(LAZY_/):VARIABLE_LIST_@'Access);
@@END_IF@@
@@END_TABLE@@
--  Register Ajax
@@TABLE@@
@@TABLE@@
@@IF@@ not @_IS_EMPTY:AJAX_EVENT_@
Services.Web_Block.Registry.Register
("/@_AJAX_EVENT_@$@_AJAX_ACTION_@",
@_PACKAGE_@.R_@_CAPITALIZE:REPLACE_ALL(\./_):AJAX_FILE_@.Template,
Web_Callbacks.@_CAPITALIZE:AJAX_EVENT_@_UNDERSCORE_@_CAPITALIZE:AJAX_ACTION_@'Access,
Content_Type     => MIME.Text_XML,
Context_Required => True);
@@END_IF@@
@@END_TABLE@@
@@END_TABLE@@
end Register;
end Lazy;

end @_PACKAGE_@;

Basically this is to write a register call for every template's tag starting with LAZY_. The second section is to write a register call for every Ajax event. All callbacks are expected to be in a package named Web_Callbacks. It is of course possible to change this template to reference callbacks for blocks and Ajax in separate packages. The use of a template here is very flexible.

Now let's parse the application HTML and XML templates and create the corresponding Ada specs and register calls:

$ templates2ada -d . -o code.ada -t templates.tada -e .thtml -e .txml
$ gnatchop code.ada

Look at the generated code below, it properly register the Widget_Counter callback to be used for rendering LAZY_WIDGET_COUNTER using the widget_counter.thtml. So we have a tight coupling between the code and the template file. If the tag is renamed in the template file the application will not compile anymore. The same is true for Ajax callbacks, every Ajax action put in a template file needs a corresponding callback in Ada. This greatly helps keeping the application code synchronized.

procedure Register is
use AWS.Services;
begin
Web_Block.Registry.Register
("LAZY_WIDGET_COUNTER",
"widget_counter.thtml",
Web_Callbacks.Widget_Counter'Access);
Services.Web_Block.Registry.Register
("/onclick$next",
WBlocks.R_Widget_Counter.Template,
Web_Callbacks.Onclick_Next'Access,
Content_Type     => MIME.Text_XML,
Context_Required => True);
end Register;

In the main, it is just now required to register the Web pages and to call the generated Register procedure:

Services.Web_Block.Registry.Register ("/", "page.thtml", null);

WBlocks.Lazy.Register;

Moreover, an Ada spec containing reference for the tag names is generated for every HTML and XML template file. All tags can be referenced using those specs, it is not needed to use string literal in the application. Again, this ensures that a tag which is renamed or deleted is detected at compilation time. For example the Widget_Counter callback can be rewritten as follow:

procedure Widget_Counter
(Request      : in              Status.Data;
Context      : not null access Web_Block.Context.Object;
Translations : in out          Templates.Translate_Set)
is
N : Natural := 0;
begin
if Context.Exist ("N") then
N := Natural'Value (Context.Get_Value ("N"));
end if;

Templates.Insert
(Translations, Templates.Assoc (WBlocks.Widget_Counter.COUNTER, N));
end Widget_Counter;

Web Cross-References
====================

When building an Ajax Web applications it is required to give ids to web elements to be able to reference them. It is also quite common to use CSS to give such and such item a specific style. After some time it is quite difficult to keep track of all those ids. Are they all used ? Don't we reference an id that does not exist anymore ?

webxref has been designed to help finding such problems.

The files kinds handled are:

.css

.tcss

     A CSS (or template CSS file). Ids and classes inside are recorded as CSS definitions.

.xml

.html

.thtml

     A meta-language document. Ids and classes inside are recorded as referencing a CSS definition and meta-language definition.

.txml

     An Ajax response file. Ids declared inside are recorded as referencing a meta-language definition.

The features are:

cross-references

     By default webxref output all the references to ids and classes.

finding unused items

     Output the ids/classes that are defined but not used. For example an id declared in a CSS but never referenced into an HTML document or an HTML id never referenced in an Ajax response file .txml document.

finding undeclared items

     Output ids/classes that are referenced but never defined. This is for example an id inside an Ajax response file which is never defined into an HTML document.

enforcing a naming scheme for ids and classes

     It can enforce a specific prefix for ids and classes. The id prefix can be based on the filename (using filename's first character and all character before an underscore). This make it less likely to find the same id on multiple files.

Note that all references are in a format recognized by tools like GPS and Emacs. It is then possible to navigate inside them easily.

All webxref options are listed using the -h option.

Using SOAP
**********

SOAP can be used to implements Web Services. The SOAP implementation uses AWS HTTP as the transport layer. SOAP is platforms and languages independent, to ensure a good inter-operability, AWS/SOAP implementation has been validated through http://validator.soapware.org/, the version number listed on this server corresponds to the AWS version string (AWS.Version) catenated with the SOAP version string (SOAP.Version).

This SOAP implementation is certainly one with the higher level of abstraction. No need to mess with a serializer, to know what is a payload or be an XML expert. All the low level stuffs are completely hidden as the SOAP type system has been binded as much as possible to the Ada type system.

The SOAP type system has been relaxed to be compatible with WSDL based SOAP implementation. In these implementations, types are generally (as in the Microsoft implementation) not part of the payload and should be taken from the WSDL (Web Services Description Language). AWS/SOAP is not WSDL compliant at this stage, all such types are binded into the Ada type system as strings. It is up to the programer to convert such strings to the desired type.

SOAP Client
===========

The SOAP client interface is quite simple. Here are the step-by-step instructions to call a SOAP Web Service:

 1. Build the SOAP parameters

     As for the SOAP servers, the SOAP parameters are built using a SOAP.Parameters.List object.

          {Params : constant Parameters.List

     := +I (10, "v1") & I (32, "v2");

 2. Build the SOAP Payload

     The Payload object is the procedure name and the associated parameters.

          {declare

     Payload : Message.Payload.Object; begin Payload := Message.Payload.Build ("Add", Params);

 3. Call the SOAP Web Service

     Here we send the above Payload to the Web Server which handles the Web Service. Let's say that this server is named myserver, it is listening on port 8082 and the SOAPAction is soapdemo.

          {Resp : constant Message.Response.Object'Class :=

     SOAP.Client.Call ("http://myserver:8082/soapdemo", Payload);

 4. Retrieve the result

     Let's say that the answer is sent back into the parameter named "myres", to get it:

          {My_Res : constant Integer := SOAP.Parameters.Get (Params, "myres");}

In the above example we have called a Web Service whose spec could be described in Ada as follow:

     {function Add (V1, V2 : in Integer) return Integer;

--  Add V1 and V2 and returns the result. In SOAP the result is named "myres"

SOAP Server
===========

A SOAP server implementation must provides a callback procedure as for standard Web server see Callback procedure. This callback must checks for the SOAP Action URI to handle both standard Web requests and SOAP ones. The SOAPAction is sent with the HTTP headers and can be retrieved using AWS.Status.SOAPAction.

Step by step instructions
-------------------------

Here are the step-by-step instructions to be followed in the SOAP callback procedure:

 1. Retrieve the SOAP Payload

     The SOAP Payload is the XML message, it contains the procedure name to be called and the associated parameters.

          {function SOAP_CB (Request : in AWS.Status.Data)

     return AWS.Response.Data is use SOAP.Types; use SOAP.Parameters;

     Payload : constant SOAP.Message.Payload.Object := SOAP.Message.XML.Load_Payload (AWS.Status.Payload (Request));

     AWS.Status.Payload returns the XML Payload as sent by the SOAP Client. This XML Payload is then parsed using SOAP.Message.XML.Load_Payload which returns a SOAP.Message.Payload.Object object.

 2. Retrieve the SOAP Parameters

     The SOAP procedure's parameters.

          {Params  : constant SOAP.Parameters.List

     := SOAP.Message.Parameters (Payload);

     SOAP.Parameters.List is a structure which holds the SOAP parameters. Each parameter can be retrieved using a SOAP.Parameters API, see SOAP.Parameters. For example to get the parameter named myStruc which is a SOAP struct:

          {My_Struct : constant SOAP_Record

     := SOAP.Parameters.Get (Params, "myStruct");

     Another example, to get the parameter named myInt which is a SOAP integer:

          {My_Int : constant Integer := SOAP.Parameters.Get (Params, "myInt");}

 3. Implements the Web Service

     This is the real job, as for any procedure you can do whatever is needed to compute the result.

 4. Build the SOAP answer

     This is the procedure answer. A SOAP answer is built from the SOAP Payload and by setting the returned parameters.

          {declare

     Resp        : SOAP.Message.Response.Object; Resp_Params : SOAP.Parameters.List; begin Resp := SOAP.Message.Response.From (Payload);

     Resp_Params := +I (My_Int * 2, "answer");

     SOAP.Message.Set_Parameters (Resp, Resp_Params);

     This build a response which is a single integer value named answer with the value My_Int * 2.

 5. Returns the answer back to the client

     This last step will encode the response object in XML and will returns it as the body of an HTTP message.

          {return SOAP.Message.Response.Build (Resp);}

SOAP helpers
------------

There is two ways to help building the SOAP callbacks. AWS provides a SOAP specific callback, the spec is :

     {function SOAP_Callback

(SOAPAction : in String;
Payload    : in Message.Payload.Object;
Request    : in AWS.Status.Data)
return AWS.Response.Data;

With both solutions exposed below, AWS retrieve the SOAPAction and the Payload from the SOAP request. This is transparent to the user.

 1. Using Utils.SOAP_Wrapper

     It is possible to dispatch to such callback by using the SOAP.Utils.SOAP_Wrapper generic routine.

          {generic

     with function SOAP_CB (SOAPAction : in String; Payload    : in Message.Payload.Object; Request    : in AWS.Status.Data) return AWS.Response.Data; function SOAP_Wrapper (Request : in AWS.Status.Data) return AWS.Response.Data; --  From a standard HTTP callback call the SOAP callback passed as generic --  formal procedure. Raise Constraint_Error if Request is not a SOAP --  request.

     For example, from the standard HTTP callback CB we want to call SOAP_CB for all SOAP requests:

          {function SOAP_CB

     (SOAPAction : in String; Payload    : in Message.Payload.Object; Request    : in AWS.Status.Data) return AWS.Response.Data is begin --  Code here end SOAP_CB;

     procedure SOAP_Wrapper is new SOAP.Utils.SOAP_Wrapper (SOAP_CB);

     function CB (Request : in AWS.Status.Data) return AWS.Response.Data is SOAPAction : constant String := Status.SOAPAction (Request); begin if SOAPAction /= "" then SOAP_Wrapper (Request); else ...

 2. Using a SOAP Dispatcher

     AWS provides also a SOAP specific dispatcher. This dispatcher will automatically calls a standard HTTP or SOAP callback depending on the request. If SOAPAction is specified (i.e. it is a SOAP request), the dispatcher will call the SOAP callback otherwise it will call the standard HTTP callback. This is by far the easiest integration procedure. Using dispatcher the above code will be written:

          {function SOAP_CB

     (SOAPAction : in String; Payload    : in Message.Payload.Object; Request    : in AWS.Status.Data) return AWS.Response.Data is begin --  Code here end SOAP_CB;

     function CB (Request : in AWS.Status.Data) return AWS.Response.Data is SOAPAction : constant String := Status.SOAPAction (Request); begin --  Code here end CB;

     --  In the main procedure

     begin AWS.Server.Start (WS, Dispatcher => SOAP.Dispatchers.Callback.Create (CB'Access, SOAP_CB'Access), Config     => AWS.Config.Default_Config);

     The dispacther is created using SOAP.Dispatchers.Callback.Create. This routine takes two parameters, one is the standard HTTP callback procedure and the other is the SOAP callback procedure.

Using WSDL
**********

WSDL (Web Service Definition Language) is an XML based document which described a set of Web Services either based on SOAP or XML/RPC. By using a WSDL document it is possible to describe, in a formal way, the interface to any Web Services. The WSDL document contains the end-point (URL to the server offering the service), the SOAPAction (needed to call the right routine), the procedure names and a description of the input and output parameters.

AWS provides two tools to work with WSDL documents:

ada2wsdl
     which creates a WSDL document from an Ada package spec.

wsdl2aws
     which create the interfaces to use a Web Service or to implement Web Services. With this tool the SOAP interface is completely abstracted out, users will deal only with Ada API. All the SOAP marshaling will be created automatically.

Creating WSDL documents
=======================

Note that this tool is based on ASIS.

Using ada2wsdl
--------------

ada2wsdl can be used on any Ada spec file to generated a WSDL document. The Ada spec is parsed using ASIS.

The simplest way to use it is:

     {$ ada2wsdl simple.ads}

Given the following Ada spec file:

     {package Simple is

function Plus (Value : in Natural) return Natural; end Simple;

It will generate the following WSDL document:

     {<?xml version="1.0" encoding="UTF-8"?>

<definitions name="Simple" targetNamespace="urn:aws:Simple" xmlns:tns="urn:aws:Simple" xmlns="http://schemas.xmlsoap.org/wsdl/" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:soap-enc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<message name="Plus_Request"> <part name="Value" type="xsd:int"/> </message>

<message name="Plus_Response"> <part name="Result" type="xsd:int"/> </message>

<portType name="Simple_PortType"> <operation name="Plus"> <input message="tns:Plus_Request"/> <output message="tns:Plus_Response"/> </operation> </portType>

<binding name="Simple_Binding" type="tns:Simple_PortType"> <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>

<operation name="Plus"> <soap:operation soapAction="Plus"/> <input> <soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" namespace="urn:aws:Simple" use="encoded"/> </input> <output> <soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" namespace="urn:aws:Simple" use="encoded"/> </output> </operation> </binding>

<service name="Simple_Service"> <port name="Simple_Port" binding="tns:Simple_Binding"> <soap:address location="http://.../"/> </port> </service> </definitions>

In bold are marked the important parts from a spec point of view. The first item is the name of the WSDL document (the name of the Ada spec package). On the portType section we have the description of the Ada Plus function. Something important to note is that in Ada a function does not have a named return parameter, ada2wsdl use Result for the response. Both the input and output parameter are mapped to SOAP xsd:int type.

Note that the SOAP address generated by default (http://.../) must be edited manually or specified using ada2wsdl's -a option.

This is of course a very simple example. ada2wsdl does support lot more complex specs and will map Ada records, arrays, enumerations, derived types to a corresponding XML schema definition. See section below for a description of the mapping.

Ada mapping to WSDL
-------------------

ada2wsdl parse Ada records, arrays, derived types, enumerations, procedures and functions and generate the corresponding WSDL document. In this section we describe the mapping between Ada and WSDL.

Integer
     Mapped to xsd:int.

Float
     Mapped to xsd:float.

Long_Float
     Mapped to xsd:double

Long_Long_Float
     Mapped to xsd:double, not supported by SOAP, mapped for convenience but precision cannot be guaranteed.

Boolean
     Mapped to xsd:boolean

String
     Mapped to xsd:string

Unbounded_String
     Mapped to xsd:string, note that Unbounded_String should be used only inside a record for full interoperability. This is a current limitation.

Character
     Mapped to a Character schema definition.

          {<simpleType name="Character">

     <restriction base="xsd:string"> <length value="1"/> </restriction> </simpleType>

SOAP.Utils.SOAP_Base64
     Mapped to xsd:base64Binary. SOAP.Utils.SOAP_Base64 is a subtype of string which is is recognized by ada2wsdl to generate the proper SOAP type.

SOAP.Types.Byte
     Mapped to xsd:byte. SOAP.Types.Byte is a type which is recognized by ada2wsdl to generate the proper SOAP type.

SOAP.Types.Short
     Mapped to xsd:short. SOAP.Types.Short is a type which is recognized by ada2wsdl to generate the proper SOAP type.

SOAP.Types.Long
     Mapped to xsd:long. SOAP.Types.Long is a type which is recognized by ada2wsdl to generate the proper SOAP type.

SOAP.Types.Unsigned_Byte
     Mapped to xsd:unsignedByte. SOAP.Types.Unsigned_Byte is a type which is recognized by ada2wsdl to generate the proper SOAP type.

SOAP.Types.Unsigned_Short
     Mapped to xsd:unsignedShort. SOAP.Types.Unsigned_Short is a type which is recognized by ada2wsdl to generate the proper SOAP type.

SOAP.Types.Unsigned_Int
     Mapped to xsd:unsignedInt. SOAP.Types.Unsigned_Int is a type which is recognized by ada2wsdl to generate the proper SOAP type.

SOAP.Types.Unsigned_Long
     Mapped to xsd:unsignedLong. SOAP.Types.Unsigned_Long is a type which is recognized by ada2wsdl to generate the proper SOAP type.

Derived types
     Mapped to a type schema definition.

          {type Number is new Integer;}

     is defined as:

          {<simpleType name="Number"

     targetNamespace="http://soapaws/WSDL_C_pkg/"> <restriction base="xsd:int"/> </simpleType>

User's types
     Mapped to a type schema definition.

          {type Small is range 1 .. 10;}

     is defined as:

          {<simpleType name="Small"

     targetNamespace="http://soapaws/WSDL_C_pkg/"> <restriction base="xsd:byte"/> </simpleType>

Enumerations
     Mapped to an enumeration schema definition. For example:

          {type Color is (Red, Green, Blue);}

     is defined as:

          {<simpleType name="Color">

     <restriction base="xsd:string"> <enumeration value="Red"/> <enumeration value="Green"/> <enumeration value="Blue"/> </restriction> </simpleType>

Records
     Mapped to a struct schema definition. For example:

          {type Rec is record

     A : Integer; B : Float; C : Long_Float; D : Character; E : Unbounded_String; F : Boolean; end record;

     is defined as:

          {<complexType name="Rec">

     <all> <element name="A" type="xsd:int"/> <element name="B" type="xsd:float"/> <element name="C" type="xsd:double"/> <element name="D" type="tns:Character"/> <element name="E" type="xsd:string"/> <element name="F" type="xsd:boolean"/> </all> </complexType>

Arrays
     Mapped to an array schema definition. For example:

          {type Set_Of_Rec is array (Positive range <>) of Rec;}

     is defined as:

          {<complexType name="Set_Of_Rec">

     <complexContent> <restriction base="soap-enc:Array"> <attribute ref="soap-enc:arrayType" wsdl:arrayType="tns:Rec[]"/> </restriction> </complexContent> </complexType>

Array inside a record
     This part is a bit delicate. A record field must be constrained but a SOAP arrays is most of the time not constrained at all. To support this AWS use a safe access array component. Such a type is built using a generic runtime support package named SOAP.Utils.Safe_Pointers. This package implements a reference counter for the array access and will release automatically the memory when no more reference exists for a given object.

     For example, let's say that we have an array of integer that we want to put inside a record:

          {type Set_Of_Int is array (Positive range <>) of Integer;}

     The first step is to create the safe array access support:

          {type Set_Of_Int_Access is access Set_Of_Int;

     package Set_Of_Int_Safe_Pointer is new SOAP.Utils.Safe_Pointers (Set_Of_Int, Set_Of_Int_Access);

     Note that the name Set_Of_Int_Safe_Pointer (<type>_Safe_Pointer) is mandatory (and checked by ada2wsdl) to achieve interoperability with wsdl2aws. see Working with WSDL documents.

     From there the safe array access can be placed into the record:

          {type Complex_Rec is record

     SI : Set_Of_Int_Safe_Pointer.Safe_Pointer; end record;

     To create a Safe_Pointer given a Set_Of_Int one must use Set_Of_Int_Safe_Pointer.To_Safe_Pointer routine. Accessing individual items is done with SI.Item (K).

     These Ada definitions are fully recognized by ada2wsdl and will generate standard array and record WSDL definitions as seen above.

          {<complexType name="Set_Of_Int">

     <complexContent> <restriction base="soap-enc:Array"> <attribute ref="soap-enc:arrayType" wsdl:arrayType="xsd:int[]"/> </restriction> </complexContent> </complexType>

     <complexType name="Complex_Rec"> <all> <element name="SI" type="tns:Set_Of_Int"/> </all> </complexType>

ada2wsdl
--------

     Usage: ada2wsdl [options] ada_spec

ada2wsdl options are:

-a url
     Specify the URL for the Web Server address. Web Services will be available at this address. A port can be specified on the URL, http://server[:port]. The default value is http://.../.

-f
     Force creation of the WSDL file. Overwrite exiting file with the same name.

-I path
     Add path option for the ASIS compilation step. This option can appear any number of time on the command line.

-noenum
     Do not generate WSDL representation for Ada enumerations, map them to standard string. see Ada mapping to WSDL.

-o file
     Generate the WSDL document into file.

-q
     Quiet mode (no output)

-s name
     Specify the Web Service name for the WSDL document, by default the spec package's name is used.

-v
     Verbose mode, display the parsed spec.

ada2wsdl limitations
--------------------

  * Do not handle constraint arrays into a records.

  * Unbounded_String are supported with full interoperability only inside a record.

  * Only unconstraint arrays are supported

  * Arrays with multiple dimentions not supported

Working with WSDL documents
===========================

Client side (stub)
------------------

This section describe how to use a Web Service. Let's say that we want to use the Barnes & Noble Price Quote service. The WSDL document for this service can be found at http://www.xmethods.net/sd/2001/BNQuoteService.wsdl. In summary this document says that there is a service named getPrice taking as input a string representing the ISBN number and returning the price as floating point.

The first step is to generate the client interface (stub):

     {$ wsdl2aws -noskel http://www.xmethods.net/sd/2001/BNQuoteService.wsdl}

This will create many files, the interesting one at this point is bnquoteservice-client.ads, inside we have:

     {function getPrice

(isbn : in String) return Float; --  Raises SOAP.SOAP_Error if the procedure fails

Let's call this service to find out the price for The Sword of Shannara Trilogy book.

     {with Ada.Text_IO;

with BNQuoteService.Client;

procedure Price is use Ada;

ISBN : constant String := "0345453751"; --  The Sword of Shannara Trilogy ISBN

package LFIO is new Text_IO.Float_IO (Float);

begin Text_IO.Put_Line ("B&N Price for The Sword of Shannara Trilogy"); LFIO.Put (BNQuoteService.Client.getPrice (ISBN), Aft => 2, Exp => 0); end Price;

That's all is needed to use this Web Service. This program is fully functional, It is possible to build it and to run it to get the answer.

Server side (skeleton)
----------------------

Building a Web Service can also be done from a WSDL document. Let's say that you are Barnes & Noble and that you want to build Web Service getPrice as described in the previous section.

You have created the WSDL document to specify the service spec. From there you can create the skeleton:

     {$ wsdl2aws -nostub http://www.xmethods.net/sd/2001/BNQuoteService.wsdl}

This will create many files, the interesting one here is bnquoteservice-server.ads, inside we have:

     {Port : constant := 80;

generic with function getPrice (isbn : in String) return Float; function getPrice_CB (SOAPAction : in String; Payload    : in SOAP.Message.Payload.Object; Request    : in AWS.Status.Data) return AWS.Response.Data;

This is a SOAP AWS's callback routine that can be instantiated with the right routine to retrieve the price of a book given its ISBN number. A possible implementation of such routine could be:

     {function getPrice

(isbn : in String) return Float is begin if isbn = "0987654321" then return 45.0; elsif ... end getPrice;

function SOAP_getPrice is new BNQuoteService.Server.getPrice_CB (getPrice);

SOAP_getPrice is a SOAP AWS's callback routine (i.e. it is not a standard callback). To use it there is different solutions:

Using SOAP.Utils.SOAP_Wrapper
     This generic function can be used to translate a standard callback based on AWS.Status.Data into a SOAP callback routine.

          {function getPrice_Wrapper is new SOAP.Utils.SOAP_Wrapper (SOAP_getPrice);}

     The routine getPrice_Wrapper can be used as any other AWS's callback routines. Note that inside this wrapper the XML payload is parsed to check the routine name and to retrieve the SOAP parameters. To call this routine the payload needs to be parsed (we need to know which routine has be invoked). In this case we have parsed the XML payload twice, this is not efficient.

Building the wrapper yourself

     This solution is more efficient if there is many SOAP procedures as the payload is parsed only once.

          {function CB (Request : in Status.Data) return Response.Data is

     SOAPAction : constant String := Status.SOAPAction (Request); Payload    : constant SOAP.Message.Payload.Object := SOAP.Message.XML.Load_Payload (AWS.Status.Payload (Request)); Proc       : constant String := SOAP.Message.Payload.Procedure_Name (Payload); begin if SOAPAction = "..." then

     if Proc = "getPrice" then return SOAP_getPrice (SOAPAction, Payload, Request); elsif ... ... end if;

     else ... end if;

Note that the port to be used by the AWS server is described into the server spec.

wsdl2aws
--------

     Usage: wsdl2aws [options] <file|URL>

It is possible to pass a WSDL file or direct wsdl2aws to a WSDL document on the Web by passing it's URL.

wsdl2aws options are:

-q
     Quiet mode (no output)

-d
     Generate debug code. Will output some information about the payload to help debug a Web Service.

-a
     Generate using Ada style names. For example getPrice will be converted to Get_Price. This formatting is done for packages, routines and formal parameters.

-f
     Force creation of the file. Overwrite any exiting files with the same name.

-e
     Specify the default endpoint to use instead of the one found in the WSDL document.

-s
     Skip non supported SOAP routines. If -s is not used, wsdl2aws will exit with an error when a problem is found while parsing the WSDL document. This option is useful to skip routines using non supported types and still be able to compile the generated files.

-o name
     Specify the name of the local WSDL document. This option can be used only when using a Web WSDL document (i.e. passing an URL to wsdl2aws).

-doc
     Handle document style binding as RPC ones. This is sometimes needed because some WSDL document specify a document style binding even though it is really an RPC one.

-v
     Verbose mode, display the parsed spec.

-v -v
     Verbose mode, display the parsed spec and lot of information while parsing the WSDL document tree.

-wsdl
     Add WSDL document as comment into the generated root unit.

-cvs
     Add CVS Id tag in every generated file.

-nostub
     Do not generated stubs, only skeletons are generated.

-noskel
     Do not generated skeletons, only stubs are generated.

-cb
     Generate a SOAP dispatcher callback routine for the server. This dispatcher routine contains the code to handle all the operations as described in the WSDL document. You need also to specify the -spec and/or -types options, see below.

-x operation
     Add operation to the list of SOAP operations to skip during the code generation. It is possible to specify multiple -x options on the command line.

-spec spec
     Specify the name of the spec containing the Ada implementation of the SOAP routines. This is used for example by the -cb option above to instantiate all the server side SOAP callbacks used by the main SOAP dispatcher routine. If -types is not specified, the type definitions are also used from this spec.

-types spec
     Specify the name of the spec containing the Ada types (record, array) used by SOAP routines specified with option -spec. If -spec is not specified, the spec definitions are also used from this spec.

-main filename
     Specify the name of the server's procedure main to generate. If file <filename>.amt (Ada Main Template) is present, it uses this template file to generate the main procedure. The template can reference the following variable tags:

     SOAP_SERVICE
          The name of the service as described into the WSDL document. This tag can be used to include the right units

               {with @_SOAP_SERVICE_@.Client;

          with @_SOAP_SERVICE_@.CB;

     SOAP_VERSION
          The AWS's SOAP version.

     AWS_VERSION
          The AWS's version.

     UNIT_NAME
          The name of the generated unit. This is the name of the procedure that will be created.

               {procedure @_UNIT_NAME_@ is

          begin ...

-proxy name|IP
     Use this proxy to access the WSDL document and generate code to access to these Web Services via this proxy. The proxy can be specified by its DNS name or IP address.

-pu name
     User name for the proxy if proxy authentication required.

-pp password
     User password for the proxy if proxy authentication required.

-timeouts [timeouts | connect_timeout,send_timeout,receive_timeout ]
     Set the timeouts for the SOAP connection. The timeouts is either a single value used for the connect, send and receive timeouts or three values separated by a colon to set each timeout independently.

wsdl2aws behind the scene
-------------------------

The wsdl2aws tool read a WSDL document and creates a root package and a set of child packages as described below:

<root>
     This is the main package, it contains eventually the full WSDL in comment and the description of the services as read from the WSDL document.

<root>.Types
     This package contains the definitions of the types which are not SOAP base types. We find here the definitions of the SOAP structs and arrays with routines to convert them between the Ada and SOAP type model. A subtype definition is also created for every routine's returned type. In fact, all definitions here are only alias or renaming of types and/or routines generated in other packages. The real definitions for structs, arrays, enumerations and derived types are generated into a package whose name depends on the name space used for these entities. This package act as a container for all definitions and it is the only one used in the other generated packages.

<root>.Client
     All spec to call Web Services.

<root>.Server
     All spec to build Web Services. These specs are all generic and must be instantiated with the right routine to create the web services.

<root>.CB
     The SOAP dispatcher callback routine.

wsdl2aws limitations
--------------------

It is hard to know all current limitations as the WSDL and SOAP world is quite complex. We list there all known limitations:

  * Some SOAP base types are not supported : date, time, xsd:hexBinary, decimal. All these are easy to add (except decimal), it is just not supported with the current version.

  * Multi-dimension arrays are not supported.

  * abstract types are not supported.

  * SOAP MIME attachments are not supported.

  * WSDL type inheritance not supported.

  * Only the RPC/Encoded SOAP messages' style is supported (the Document/Literal is not)

Using ada2wsdl and wsdl2aws together
====================================

Using both tools together is an effective way to build rapidely a SOAP server. It can be said that doing so is quite trivial in fact. Let's take the following spec:

     {package Graphics is

type Point is record X, Y : Float; end record;

function Distance (P1, P2 : in Point) return Float; --  Returns the distance between points P1 and P2

end Graphics;

We do not show the body here but we suppose it is implemented. To build a server for this service it is as easy as:

     {$ ada2wsdl -a http://localhost:8787 -o graphics.wsdl graphics.ads}

The server will be available on localhost at port 8787.

     {$ wsdl2aws -cb -main server -types graphics graphics.wsdl

$ gnatmake server -largs ...

Options

-cb
     is to create the SOAP dispatcher callback routine,

-main server
     to generate the main server procedure in server.adb,

-types graphics
     to use graphics.ads to get references from user's spec (reference to Graphics.Point for example).

Working with mails
******************

Sending e-mail
==============

AWS provides a complete API to send e-mail using SMTP protocol. You need to have access to an SMTP server to use this feature. The API covers sending simple mail with text message and/or with MIME attachments (base64 encoded). Here are the steps to send a simple e-mail:

  * Initialize the SMTP server

          {SMTP_Server : SMTP.Receiver

     := SMTP.Client.Initialize ("smtp.hostname");

     Here AWS uses the default SMTP port to create an SMTP mail server but it is possible to specify a different one. The hostname specified must be a valid SMTP server.

  * Send the e-mail

     To send an e-mail there is many different API. Let's send a simple text mail.

          {Status : SMTP.Status;

     SMTP.Client.Send (SMTP_Server, From    => SMTP.E_Mail ("Pascal Obry", "p.obry@wanadoo.fr"), To      => SMTP.E_Mail ("John Doe", "john.doe@here.com"), Subject => "About AWS SMTP protocol", Message => "AWS can now send mails", Status  => Status);

     Here Status will contain the SMTP returned status.

  * Check that everything is ok

     Using above status data it is possible to check that the message was sent or not by the server. The status contain a code and an error message, both of them can be retrieved using specific routines, see AWS.SMTP. It is also possible to check that the call was successful with SMTP.Is_Ok routine.

          {if not SMTP.Is_Ok (Status) then

     Put_Line ("Can't send message: " & SMTP.Status_Message (Status)); end if;

In the above example, the message content was given as a string but it is possible to specify a disk file. AWS can also send MIME messages either from disk files or with in memory base64 encoded binary data. The API provides also a way to send messages to multiple recipients at the same time and to send messages with alternative contents (text and HTML for example). These features are not described here, complete documentation can be found on the spec see AWS.SMTP and see AWS.SMTP.Client.

Retrieving e-mail
=================

AWS provides an API to retrieve e-mails from a POP mailbox. POP stands for Post Office Protocol and is the main protocol used by Internet Service Providers around the world. IMAP is another well known protocol in this area but it is not supported by AWS.

We describes here the POP API. For a complete description see AWS.POP.

  * Opening the mailbox

     The first step is to authenticate using a user name and password. AWS supports two methods one called Clear_Text which is the most used and another one APOP which is more secure but almost not supported by ISP for the moment (and will probably never be supported as a more secure protocol named SPA -Secure Password Authentication- could be used instead).

          {Mailbox : POP.Mailbox

     := POP.Initialize ("pop.hostname", "john.does", "mysuperpwd");

     The default Authentication method is Clear_Text.

  * Getting mailbox information

     When the connection is opened it is possible to get information about the mailbox like the number of messages or the total number of bytes in the mailbox.

          {N     : constant Natural := POP.Message_Count (Mailbox);

     Bytes : constant Natural := POP.Size (Mailbox);

  * Retreiving individual e-mail

     Each message is numbered starting from 1. A function named Get will return a message given its mailbox's number.

          {Message : constant POP.Message := POP.Get (Mailbox, 2, Remove => True);}

     Remove can be set to False for the message to stay on the mailbox. The default value is False.

  * Iterating through the mailbox content

     Another way to retreive message is by using an iterator.

          {procedure Print_Subject

     (Message : in     POP.Message
     Index   : in     Positive;
     Quit    : in out Boolean) is
     begin
     Text_IO.Put_Line (POP.Subject (Message));
     end Print_Message;

     procedure Print_All_Subjects is new POP.For_Every_Message (Print_Subject);

     ...

     Print_All_Subjects (Mailbox, Remove => True);

     It exists a set of routines on a POP.Message object to get the subject the content, the date or any headers. It is also possible to work with attachments. See point below.

  * Working with attachments

     A message can have a set of MIME attachments. The number of attachments can be retrieved using Attachment_Count.

          {Message : constant POP.Message := ...;

     A_Count : constant Natural := POP.Attachment_Count (Message);

     As for messages it is possible to get a single attachment using its index in the message or by using an iterator.

          {First_Attachment : constant POP.Attachment := POP.Get (Message, 1);

     procedure Write_Attachment (Attachment : in     POP.Attachment Index      : in     Positive; Quit       : in out Boolean) is begin POP.Write (Attachment, Directory => "."); end Print_Message;

     procedure Write_All_Attachments is new POP.For_Every_Attachment (Write_Attachment);

     ...

     Write_All_Attachments (Message);

     It is also possible to retrieve the attachment's filename, the content as a memory stream. see AWS.POP.

  * Closing the connection

          {POP.Close (POP_Server);}

LDAP
****

AWS provides a complete API to retrieve information from LDAP servers. Note that there is no support for updating, modifying or deleting information only to read information from the server.

The AWS/LDAP implementation is based on OpenLDAP. To build an LDAP application you need to link with the libldap.a library. This library is built by AWS on Windows based system and will use the wldap32.dll as provided with Windows NT/2000/XP. On UNIX based systems, you must install properly the OpenLDAP package.

The steps required to read information from an LDAP server are:

Initialize the LDAP directory

          {declare

     Directory : LDAP.Client.Directory; begin Directory := LDAP.Client.Init (Host);

     Host is the hostname where the LDAP directory is running. It is possible to specify the port if the LDAP server does not use the default one.

Bind to the LDAP server

     This step is the way to pass a login/password if the LDAP server required an authentication. If not, the login/password must be empty strings.

          {LDAP.Client.Bind (Directory, "", "");}

Do the search

     For the search you must specify the base name, a filter, the scope and a set of attributes to retrieve.

          {Response_Set := LDAP.Client.Search

     (Directory, Base_DN, Filter, LDAP.Client.LDAP_Scope_Subtree, LDAP.Client.Attributes ("cn", "sn", "telephonenumber"));

     Attributes
          The set of attributes to retrieve from the directory.

     Filter
          A set of values for some attributes. A filter is <attribute_name>=<value> where value can contain '*' at the end. For example "(cn=DUPON*)" will look for all entries where the common name is starting by the string "DUPON".

     Scope
          Define how far in the hierarchical directory the search will operate. It is either one level, all subtrees or on the base of the tree.

     For more information see AWS.LDAP.Client.

Iterate through the response set

     For this there is two iterators. First_Entry/Next_Entry or the generic high level iterator For_Every_Entry.

          {declare

     Message : LDAP.Client.LDAP_Message; begin Message := LDAP.Client.First_Entry (Directory, Response_Set);

     while Message /= LDAP.Client.Null_LDAP_Message loop

     Do_Job (Message);

     Message := LDAP.Client.Next_Entry (Directory, Message); end loop; end;

Read attributes for each entry

     Each entry has an associated set of attributes. To retrieve attributes values there is two iterators. First_Attribute / Next_Attribute or the generic high level iterator For_Every_Attribute.

          {declare

     BER : aliased LDAP.Client.BER_Element;

     Attr : constant String := LDAP.Client.First_Attribute (Directory, Message, BER'Unchecked_Access); begin Do_Job (Attr);

     loop declare Attr : constant String := LDAP.Client.Next_Attribute (Directory, Message, BER); begin exit when Attr = ""; Do_Job (Attr); end; end loop; end;

Cleanup

     At the end of the processing it is important to release memory associated with LDAP objects.

          {LDAP.Client.Free (Message);

     LDAP.Client.Unbind (Directory);

see AWS.LDAP.Client for all high level supported API and documentation.

Note that for complete information about AWS/LDAP you you should read an LDAP API description. AWS/LDAP is only a binding and follow the LDAP API closely.

Jabber
******

AWS support part of the Jabber protocol. At this stage only two kind of messages are supported:

 1. Presence

     To check the presence status of a specific JID (Jabber ID)

 2. Message

     To send messages to a specific JID (Jabber ID)

Note that if you want an application to check the presence or send message to users it is recommended to create a specific Jabber ID on the server for this application and ask users to accept this specific user to check their presence status.

Jabber presence
===============

To check for the presence of another JID you must first have the right to do so. The jabber server won't let you see presence of another JID unless the JID have permitted you to see its presence.

  * First declare the server and status objects

          {Server : AWS.Jabber.Server;

     Status : AWS.Jabber.Presence_Status;

  * Connect to the server, you must have an account created and must know the login and password

          {AWS.Jabber.Connect

     (Server, "jabber.domain.org", "joe", "mysuperpwd");

  * Then, to check the presence of user "john"

          {AWS.Jabber.Check_Presence

     (Server, "john@jabber.domain.org", Status);

  * Then, you just have to close the server

          {AWS.Jabber.Close (Server);}

Jabber message
==============

To send a message to a specific JID, you must connect to the server as above and close the server when you don't need to communicate with it anymore. The only different part is to send the message, here is an example:

     {Send_Message

(Server, JID     => "john@jabber.domain.org", Subject => "Hello there!", Content => "Are you using AWS ?");

It is as simple as that !

Resources
*********

AWS support embedded resources. It means that it is possible to build a fully self dependent executable. This is useful when distributing a server. The server program contains the code but also the images (PNG, JPEG, GIF), the templates, the HTML pages... more generally any file the Web Server must serve to clients.

Building resources
==================

To embbed the files into the executable you must build a resource tree. This task is greatly simplified using AWSRes tool. For example let's say that you want to build a simple server with a single page containing some text and one PNG image. The text is handled directly in the callback procedure and contain a reference to the image logo.png. To build the resource tree:

     {$ awsres logo.png}

This will create a set of packages whose root is the unit res by default. The resource tree is created. see awsres tool for the complete AWS's usage description.

awsres can also compress the resource files. This can be done by using awsres's -z option. Compressed resources are handled transparently. If the Web client supports compression the resource is sent as-is otherwise a decompression stream will be created for the resource to be decompressed on-the-fly while sending it.

Using resources
===============

This is really the simplest step. The resource tree must be linked with your executable, to do so you just have to ``with'' the resource tree root into one of your program unit. This will ensure that the resource tree will be compiled and linked into the executable. AWS and Templates_Parser know about resource files and will pick them up if available.

Note that this is transparent to users. It is possible to build the very same server based on standard files or resources files. The only change in the code is to ``with'' or not the resource tree.

Note that AWS supports only a single resource tree. If more than one resource tree is included into a program only one will be seen.

Stream resources
================

Users can build a response directly from a stream. In this case the callback answer is built using AWS.Response.Stream. It creates a resource object whose operations have been inherited from AWS.Resource.Stream.Stream_Type and redefined by the user. So the Read operation can dynamically create the result stream data, the End_Of_File operation must returns True when the stream data is out and so on. This feature is useful to let users completely create and control dynamically AWS's response content.

see AWS.Resources.Streams.

awsres tool
===========

AWSRes is a tool to build resource files. It creates a root package named res by default and a child package for each resource file.

Usage: awsres [-hrquz] file1 [-uz] [file2...]

-h
     Display help message.

-q
     Quiet mode.

-r name
     Set the root unit name. Default is res.

-u
     Add following files as uncompressed resources.

-z
     Add following files as compressed resources.

Status page
***********

The status page gives information about the AWS internal status. For example it returns the server socket ID, the number of simultaneous connection, the number of time a connection has been used...

To display the information AWS use a template file. The
template file (default is _STATUS_PAGE_}) is an HTML file with
some specific tags recognized by the parser. For more information
about how the template parser works, please look for the template
parser documentation distributed with AWS.

Here are the tag variables recognized by AWS status page:

ABORTABLE_V (vector tag)

     A list of boolean. One for each connection. True means that this connection can be aborted if none is available. This is to be inserted in a template table.

ACCEPT_QUEUE_SIZE

     see Configuration options.

ACCEPTOR_LENGTH

     Number of sockets in the internal socket set.

ACTIVITY_COUNTER_V (vector tag)

     A list of natural. One for each connection. This is the number of request the connection has answered. This counter is reset each time the connection is closed. In other word this is the number of request a keep-alive connection has processed.

ACTIVITY_TIME_STAMP_V (vector tag)

     A list of date. One for each connection. This is the time of the latest request answered.

ADMIN

     URI to the administrative page.

CASE_SENSITIVE_PARAMETERS

     see Configuration options.

CHECK_URL_VALIDITY

     see Configuration options.

CLEANER_CLIENT_DATA_TIMEOUT

     see Configuration options.

CLEANER_CLIENT_HEADER_TIMEOUT

     see Configuration options.

CLEANER_SERVER_RESPONSE_TIMEOUT

     see Configuration options.

CLEANER_WAIT_FOR_CLIENT_TIMEOUT

     see Configuration options.

CURRENT_CONNECTIONS

     Number of current connections to the server.

ERROR_LOG (boolean tag)

     This is set to true if error logging is active.

ERROR_LOG_FILE

     The error log file full pathname.

ERROR_LOG_FILENAME_PREFIX

     see Configuration options.

ERROR_LOG_SPLIT_MODE

     see Configuration options.

FORCE_CLIENT_DATA_TIMEOUT

     see Configuration options.

FORCE_CLIENT_HEADER_TIMEOUT

     see Configuration options.

FORCE_SERVER_RESPONSE_TIMEOUT

     see Configuration options.

FORCE_WAIT_FOR_CLIENT_TIMEOUT

     see Configuration options.

FREE_SLOTS_KEEP_ALIVE_LIMIT

     see Configuration options.

LINE_STACK_SIZE

     see Configuration options.

KEYS_M (matrix tag)

     A list of set of keys (for each key correspond a value in the tag VALUES_L, see below). Each key in the vector tag start with an HTML "<td>" tag. This is to be able to display the key/value in column.

LOG (boolean tag)

     This is set to true if logging is active.

LOG_FILE

     The log file full pathname.

LOG_FILENAME_PREFIX

     see Configuration options.

LOG_FILE_DIRECTORY

     see Configuration options.

LOG_MODE

     The rotating log mode, this is either NONE, DAILY, MONTHLY or EACH_RUN.

LOGO

     A string to be placed in an img HTML tag. This is the name of the AWS logo image.

MAX_CONCURRENT_DOWNLOAD

     see Configuration options.

MAX_CONNECTION

     see Configuration options.

PEER_NAME_V (vector tag)

     A list of peer name. One for each connection. This is the name of the last peer connected to the slot.

PHASE_V (vector tag)

     What is the slot currently doing, for example Server_Processing or Closed.

RECEIVE_TIMEOUT

     see Configuration options.

REUSE_ADDRESS

     see Configuration options.

SECURITY

     A boolean set to True if this is a secure socket (HTTPS/SSL).

SECURITY_MODE

     see Configuration options.

SEND_TIMEOUT

     see Configuration options.

SERVER_HOST

     see Configuration options.

SERVER_NAME

     see Configuration options.

SERVER_PORT

     see Configuration options.

SERVER_SOCK

     Server socket ID.

SESSION

     see Configuration options.

SESSION_CLEANUP_INTERVAL

     Number of seconds between each run of the session cleanup task. This task will remove all session data that have been obsoleted.

SESSION_LIFETIME

     Number of seconds to keep session information. After this period a session is obsoleted and will be removed at next cleanup.

SESSION_NAME

     see Configuration options.

SESSIONS_TERMINATE_V (vector tag)

     A list of time. Each item correspond to the time when the session will be obsoleted.

SESSIONS_TS_V (vector tag)

     A list of time stamp. Each item correspond to a session last access time.

SESSIONS_V (vector tag)

     A list of session ID.

SLOT_ACTIVITY_COUNTER_V (vector tag)

     A list of natural. One for each connection. This is the total number of requests the slot has answered. This counter is never reseted.

SOCK_V (vector tag)

     A list of sockets ID. One for each connection.

STATUS_PAGE

     see Configuration options.

START_TIME

     A timestamp in YYYY-MM-DD HH:MM:SS format. When the server was started.

TRANSIENT_CLEANUP_INTERVAL

     see Configuration options.

TRANSIENT_LIFETIME

     see Configuration options.

UPLOAD_DIRECTORY

     see Configuration options.

UPLOAD_SIZE_LIMIT

     see Configuration options.

VALUES_M (matrix tag)

     A list of set of values (for each value correspond a key in the vector tag KEYS_L, see above). Each key in the vector tag start with an HTML "<td>" tag. This is to be able to display the key/value in column.

VERSION

     AWS version string.

WWW_ROOT

     see Configuration options.

There is also all Templates_Parser specific tags. This is not listed here please have a look at the Templates_Parser documentation distributed with AWS.

References
**********

Here is a list of documents used to implement AWS, the SOAP support and associated services:

RFC 0821

                               SIMPLE MAIL TRANSFER PROTOCOL

                                     Jonathan B. Postel
                                        August 1982

                               Information Sciences Institute
                             University of Southern California
                                     4676 Admiralty Way
                             Marina del Rey, California  90291

RFC 1867

          Network Working Group                                           E. Nebel
          Request For Comments: 1867                                   L. Masinter
          Category: Experimental                                 Xerox Corporation
                                                                     November 1995

                               Form-based File Upload in HTML

RFC 1939

          Network Working Group                                           J. Myers
          Request for Comments: 1939                               Carnegie Mellon
          STD: 53                                                          M. Rose
          Obsoletes: 1725                             Dover Beach Consulting, Inc.
          Category: Standards Track                                       May 1996

                              Post Office Protocol - Version 3

RFC 1945

          Network Working Group                                     T. Berners-Lee
          Request for Comments: 1945                                       MIT/LCS
          Category: Informational                                      R. Fielding
                                                                         UC Irvine
                                                                        H. Frystyk
                                                                           MIT/LCS
                                                                          May 1996

                          Hypertext Transfer Protocol -- HTTP/1.0

RFC 2049

          Network Working Group                                          N. Freed
          Request for Comments: 2049                                     Innosoft
          Obsoletes: 1521, 1522, 1590                               N. Borenstein
          Category: Standards Track                                 First Virtual
                                                                    November 1996

                           Multipurpose Internet Mail Extensions
                                     (MIME) Part Five:
                             Conformance Criteria and Examples

RFC 2109

          Network Working Group                                         D. Kristol
          Request for Comments: 2109        Bell Laboratories, Lucent Technologies
          Category: Standards Track                                    L. Montulli
                                                           Netscape Communications
                                                                     February 1997

                              HTTP State Management Mechanism

RFC 2195

          Network Working Group                                       J. Klensin
          Request for Comments: 2195                                    R. Catoe
          Category: Standards Track                                 P. Krumviede
          Obsoletes: 2095                                                    MCI
                                                                  September 1997

                 IMAP/POP AUTHorize Extension for Simple Challenge/Response

RFC 2554

          Network Working Group                                           J. Myers
          Request for Comments: 2554                       Netscape Communications
          Category: Standards Track                                     March 1999

                                   SMTP Service Extension
                                     for Authentication

RFC 2616

          Network Working Group                                      R. Fielding
          Request for Comments: 2616                                   UC Irvine
          Obsoletes: 2068                                              J. Gettys
          Category: Standards Track                                   Compaq/W3C
                                                                        J. Mogul
                                                                          Compaq
                                                                      H. Frystyk
                                                                         W3C/MIT
                                                                     L. Masinter
                                                                           Xerox
                                                                        P. Leach
                                                                       Microsoft
                                                                  T. Berners-Lee
                                                                         W3C/MIT
                                                                       June 1999

                          Hypertext Transfer Protocol -- HTTP/1.1

RFC 2617

          Network Working Group                                          J. Franks
          Request for Comments: 2617                       Northwestern University
          Obsoletes: 2069                                          P. Hallam-Baker
          Category: Standards Track                                 Verisign, Inc.
                                                                      J. Hostetler
                                                                   AbiSource, Inc.
                                                                       S. Lawrence
                                                             Agranat Systems, Inc.
                                                                          P. Leach
                                                             Microsoft Corporation
                                                                       A. Luotonen
                                               Netscape Communications Corporation
                                                                        L. Stewart
                                                                 Open Market, Inc.
                                                                         June 1999

                HTTP Authentication: Basic and Digest Access Authentication

draft 302

          Transport Layer Security Working Group                  Alan O. Freier
          INTERNET-DRAFT                                 Netscape Communications
          Expire in six months                                    Philip Karlton
                                                         Netscape Communications
                                                                  Paul C. Kocher
                                                          Independent Consultant
                                                               November 18, 1996

                                    The SSL Protocol
                                      Version 3.0

SOAP (W3C Note 08 May 2000)

          Simple Object Access Protocol (SOAP) 1.1

          W3C Note 08 May 2000

          This version:
             http://www.w3.org/TR/2000/NOTE-SOAP-20000508

          Latest version:
             http://www.w3.org/TR/SOAP

          Authors (alphabetically):
             Don Box, DevelopMentor
             David Ehnebuske, IBM
             Gopal Kakivaya, Microsoft
             Andrew Layman, Microsoft
             Noah Mendelsohn, Lotus Development Corp.
             Henrik Frystyk Nielsen, Microsoft
             Satish Thatte, Microsoft
             Dave Winer, UserLand Software, Inc.

          Copyright 2000 DevelopMentor, International Business Machines Corporation,
          Lotus Development Corporation, Microsoft, UserLand Software

     http://www.w3.org/TR/SOAP/

A Busy Developer's Guide to SOAP 1.1

          By Dave Winer, Jake Savin, UserLand Software, 4/2/01.

     http://www.soapware.org/bdg

AWS API Reference
*****************

AWS
===

     [file aws.ads.texi not included]

AWS.Attachments
===============

     [file aws-attachments.ads.texi not included]

AWS.Client
==========

     [file aws-client.ads.texi not included]

AWS.Client.Hotplug
==================

     [file aws-client-hotplug.ads.texi not included]

AWS.Communication
=================

     [file aws-communication.ads.texi not included]

AWS.Communication.Client
========================

     [file aws-communication-client.ads.texi not included]

AWS.Communication.Server
========================

     [file aws-communication-server.ads.texi not included]

AWS.Config
==========

     [file aws-config.ads.texi not included]

AWS.Config.Ini
==============

     [file aws-config-ini.ads.texi not included]

AWS.Config.Set
==============

     [file aws-config-set.ads.texi not included]

AWS.Containers.Tables
=====================

     [file aws-containers-tables.ads.texi not included]

AWS.Cookie
==========

     [file aws-cookie.ads.texi not included]

AWS.Default
===========

     [file aws-default.ads.texi not included]

AWS.Dispatchers
===============

     [file aws-dispatchers.ads.texi not included]

AWS.Dispatchers.Callback
========================

     [file aws-dispatchers-callback.ads.texi not included]

AWS.Exceptions
==============

     [file aws-exceptions.ads.texi not included]

AWS.Headers
===========

     [file aws-headers.ads.texi not included]

AWS.Headers.Values
==================

     [file aws-headers-values.ads.texi not included]

AWS.Jabber
==========

     [file aws-jabber.ads.texi not included]

AWS.LDAP.Client
===============

     [file aws-ldap-client.ads.texi not included]

AWS.Log
=======

     [file aws-log.ads.texi not included]

AWS.Messages
============

     [file aws-messages.ads.texi not included]

AWS.MIME
========

     [file aws-mime.ads.texi not included]

AWS.Net
=======

     [file aws-net.ads.texi not included]

AWS.Net.Buffered
================

     [file aws-net-buffered.ads.texi not included]

AWS.Net.Log
===========

     [file aws-net-log.ads.texi not included]

AWS.Net.Log.Callbacks
=====================

     [file aws-net-log-callbacks.ads.texi not included]

AWS.Net.SSL
===========

     [file aws-net-ssl.ads.texi not included]

AWS.Net.SSL.Certificate
=======================

     [file aws-net-ssl-certificate.ads.texi not included]

AWS.Parameters
==============

     [file aws-parameters.ads.texi not included]

AWS.POP
=======

     [file aws-pop.ads.texi not included]

AWS.Resources
=============

     [file aws-resources.ads.texi not included]

AWS.Resources.Embedded
======================

     [file aws-resources-embedded.ads.texi not included]

AWS.Resources.Files
===================

     [file aws-resources-files.ads.texi not included]

AWS.Resources.Streams
=====================

     [file aws-resources-streams.ads.texi not included]

AWS.Resources.Streams.Disk
==========================

     [file aws-resources-streams-disk.ads.texi not included]

AWS.Resources.Streams.Disk.Once
===============================

     [file aws-resources-streams-disk-once.ads.texi not included]

AWS.Resources.Streams.Memory
============================

     [file aws-resources-streams-memory.ads.texi not included]

AWS.Resources.Streams.Memory.ZLib
=================================

     [file aws-resources-streams-memory-zlib.ads.texi not included]

AWS.Resources.Streams.Pipe
==========================

     [file aws-resources-streams-pipe.ads.texi not included]

AWS.Response
============

     [file aws-response.ads.texi not included]

AWS.Server
==========

     [file aws-server.ads.texi not included]

AWS.Server.Hotplug
==================

     [file aws-server-hotplug.ads.texi not included]

AWS.Server.Log
==============

     [file aws-server-log.ads.texi not included]

AWS.Server.Push
===============

     [file aws-server-push.ads.texi not included]

AWS.Server.Status
=================

     [file aws-server-status.ads.texi not included]

AWS.Services.Callbacks
======================

     [file aws-services-callbacks.ads.texi not included]

AWS.Services.Directory
======================

     [file aws-services-directory.ads.texi not included]

AWS.Services.Dispatchers
========================

     [file aws-services-dispatchers.ads.texi not included]

AWS.Services.Dispatchers.Linker
===============================

     [file aws-services-dispatchers-linker.ads.texi not included]

AWS.Services.Dispatchers.Method
===============================

     [file aws-services-dispatchers-method.ads.texi not included]

AWS.Services.Dispatchers.URI
============================

     [file aws-services-dispatchers-uri.ads.texi not included]

AWS.Services.Dispatchers.Virtual_Host
=====================================

     [file aws-services-dispatchers-virtual_host.ads.texi not included]

AWS.Services.Download
=====================

     [file aws-services-download.ads.texi not included]

AWS.Services.Page_Server
========================

     [file aws-services-page_server.ads.texi not included]

AWS.Services.Split_Pages
========================

     [file aws-services-split_pages.ads.texi not included]

AWS.Services.Split_Pages.Alpha
==============================

     [file aws-services-split_pages-alpha.ads.texi not included]

AWS.Services.Split_Pages.Alpha.Bounded
======================================

     [file aws-services-split_pages-alpha-bounded.ads.texi not included]

AWS.Services.Split_Pages.Uniform
================================

     [file aws-services-split_pages-uniform.ads.texi not included]

AWS.Services.Split_Pages.Uniform.Alpha
======================================

     [file aws-services-split_pages-uniform-alpha.ads.texi not included]

AWS.Services.Split_Pages.Uniform.Overlapping
============================================

     [file aws-services-split_pages-uniform-overlapping.ads.texi not included]

AWS.Services.Transient_Pages
============================

     [file aws-services-transient_pages.ads.texi not included]

AWS.Services.Web_Block
======================

     [file aws-services-web_block.ads.texi not included]

AWS.Services.Web_Block.Context
==============================

     [file aws-services-web_block-context.ads.texi not included]

AWS.Services.Web_Block.Registry
===============================

     [file aws-services-web_block-registry.ads.texi not included]

AWS.Session
===========

     [file aws-session.ads.texi not included]

AWS.SMTP
========

     [file aws-smtp.ads.texi not included]

AWS.SMTP.Client
===============

     [file aws-smtp-client.ads.texi not included]

AWS.Status
==========

     [file aws-status.ads.texi not included]

AWS.Templates
=============

     [file aws-templates.ads.texi not included]

AWS.Translator
==============

     [file aws-translator.ads.texi not included]

AWS.URL
=======

     [file aws-url.ads.texi not included]

SOAP
====

     [file soap.ads.texi not included]

SOAP.Client
===========

     [file soap-client.ads.texi not included]

SOAP.Dispatchers
================

     [file soap-dispatchers.ads.texi not included]

SOAP.Dispatchers.Callback
=========================

     [file soap-dispatchers-callback.ads.texi not included]

SOAP.Message
============

     [file soap-message.ads.texi not included]

SOAP.Message.XML
================

     [file soap-message-xml.ads.texi not included]

SOAP.Parameters
===============

     [file soap-parameters.ads.texi not included]

SOAP.Types
==========

     [file soap-types.ads.texi not included]