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<?xml version="1.0" encoding="iso-8859-1"?>

<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
  "http://www.oasis-open.org/committees/docbook/xml/4.1.2/docbookx.dtd" [
      <!ENTITY hello.rvt SYSTEM "examples/hello.rvt" >
      <!ENTITY table.rvt SYSTEM "examples/table.rvt" >
      <!ENTITY vars.html SYSTEM "examples/vars.html" >
      <!ENTITY vars.rvt SYSTEM "examples/vars.rvt" >
      <!ENTITY upload.html SYSTEM "examples/upload.html" >
      <!ENTITY upload.rvt SYSTEM "examples/upload.rvt" >
]>

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   Copyright 2002-2004 The Apache Software Foundation

   Licensed under the Apache License, Version 2.0 (the "License"); you
   may not use this file except in compliance with the License.  You
   may obtain a copy of the License at

   	http://www.apache.org/licenses/LICENSE-2.0

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   implied.  See the License for the specific language governing
   permissions and limitations under the License.
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<!-- $Id: rivet.xml,v 1.52 2005/03/12 14:26:20 davidw Exp $ -->

<article>
  <articleinfo>
    <title>Apache Rivet</title>
    <copyright>
      <year>2002</year>
      <year>2003</year>
      <year>2004</year>
      <holder>Apache Software Foundation</holder>
    </copyright>
    <author>
      <firstname>The Rivet Team</firstname>
      <affiliation>
	<orgname>The Apache Software Foundation</orgname>
	<address>
	  <email>rivet-dev@tcl.apache.org</email>
	</address>
      </affiliation>
    </author>
  </articleinfo>
  <para>
    This document is also available in the following languages: <ulink
    url="index.it.html">Italian</ulink>, <ulink
    url="index.ru.html">Russian</ulink>
  </para>

  <para>
    Document revision: $Revision: 1.52 $, last modified $Date: 2005/03/12 14:26:20 $ by $Author: davidw $.
  </para>

  <section>
    <title>Introduction to Apache Rivet</title>
    <para>
      Apache Rivet is a system for creating dynamic web content via a
      programming language integrated with Apache Web Server.  It is
      designed to be fast, powerful and extensible, consume few system
      resources, be easy to learn, and to provide the user with a
      platform that can also be used for other programming tasks
      outside the web (GUI's, system administration tasks, text
      processing, database manipulation, XML, and so on).  In order to
      meet these goals, we have chosen the Tcl programming language to
      combine with the Apache Web Server.
    </para>
    <para>
      In this manual, we aim to help get you started, and then
      writing productive code as quickly as possible, as well as
      giving you ideas on how to best take advantage of Rivet's
      architecture to create different styles of web site.
    </para>

    <para>
      This documentation is a work in progress, and, like everything
      else about Apache Rivet, it is Free Software.  If you see
      something that needs improving, and have ideas or suggestions,
      don't hesitate to let us know.  If you want to contribute
      directly, better yet!
    </para>
  </section>


  <section id="installation">
    <title>Apache Rivet Installation</title>

    <procedure>
      <step>
	<title>Check Dependencies</title>
	<para>
	  To install Rivet, you will need Tcl 8.2 or greater and
	  Apache 1.3.xx.  It is known to run on Linux, FreeBSD,
	  OpenBSD, and Solaris and HPUX.  Windows NT is also possible
	  - please see the directions in the distribution.
	</para>
      </step>
      <step>
	<title>Get Rivet</title>
	<para>
	  Download the sources at <ulink
	    url="http://tcl.apache.org/rivet/download"/>.  Currently
	  the only way to obtain Rivet.  In the future, we hope to
	  have a FreeBSD port, Debian package, RPM's, and windows
	  binaries.
	</para>
      </step>
      <step performance="required">
	<title>Install Tcl</title>
	<para>
	  If you don't have Tcl already, you need it!  If you already
	  have it, you should just be able to use your system Tcl as
	  long as it is recent.  You can tell Rivet where Tcl is via
	  the <option>-with-tclconfig</option> option to
	  <command>configure.tcl</command> (see below).</para>
      </step>
      <step performance="optional">
	<title>Get and Install Apache Sources</title>
	<para>
          Rivet needs some Apache include (.h) files in order to
	  build.  The easiest way to get them is to download the
	  source code of the Apache web server, although some systems
	  (Debian GNU/Linux for example) make it possible to install
	  only the headers and other development files.  If you intend
	  to build Rivet statically (compiled into the Apache web
	  server instead of loaded dynamically), you definitely need
	  the sources.  We recommend that you build Rivet as a
	  loadable shared library, for maximum flexibility, meaning
	  that you also build Apache to be able to load modules.
	  Other than that, the default Apache install is fine.  We
	  will tell Rivet where it is located via the
	  <option>-with-apxs</option> option to
	  <command>configure.tcl</command> (see below).
	</para>
	<para>
          The source code for the Apache web server may be found by
          following the links here: <ulink
          url="http://httpd.apache.org/"/>.
	</para>
      </step>
      <step>
	<title>Uncompress Sources</title>
	<para>
	  We will assume that you have Apache installed at this point.
	  You must uncompress the Rivet sources in the directory where you
	  wish to compile them.

	  <programlisting>gunzip tcl-rivet-X.X.X.tar.gz
tar -xvf tcl-rivet-X.X.X.tar.gz</programlisting>

	</para>
      </step>
      <step>
	<title>Building Rivet</title>
	<para>
	  On Linux or Unix systems, Rivet uses the standard
	  ./configure ; make ; make install technique.
	</para>
	<substeps>
	  <step>
	    <title>Run ./configure.tcl</title>
	    <para>
	      This is similar to the <filename>configure</filename>
	      script included with many systems.  It's written in Tcl
	      though, for increased speed and clarity.  It takes
	      several arguments:
	    </para>

	    <variablelist>
	      <varlistentry>
		<term>-help</term>
		<listitem>
		  <para>Prints usage information.</para>
		</listitem>
	      </varlistentry>
	      <varlistentry>
		<term>-enable-symbols</term>
		<listitem>
		  <para>Compiles Rivet with debugging symbols.</para>
		</listitem>
	      </varlistentry>
	      <varlistentry>
		<term>-prefix <replaceable>directory</replaceable></term>
		<listitem>
		  <para>
		    Install Rivet Tcl packages to
		    <replaceable>directory</replaceable>.
		  </para>
		</listitem>
	      </varlistentry>
	      <varlistentry>
		<term>-with-apxs <replaceable>file</replaceable></term>
		<listitem>
		  <para>Use <replaceable>file</replaceable> as apxs binary to
		  gather information about the local Apache installation.</para>
		</listitem>
	      </varlistentry>
	      <varlistentry>
		<term>-with-tclconfig <replaceable>path/to/tcl/tclConfig.sh</replaceable></term>
		<listitem>
		  <para>
		    Specify <replaceable>file</replaceable> as the
		    tclConfig.sh of the Tcl installation that you want
		    to use with Rivet.
		  </para>
		</listitem>
	      </varlistentry>
	    </variablelist>

	    <programlisting>cd src/
./configure.tcl
Configuring
.........done.</programlisting>

	  </step>
	  <step>
	    <title>Run make.tcl</title>
	    <para>
	      At this point, you are ready to run the build
	      system:
	    </para>

	    <programlisting>./make.tcl <replaceable>option</replaceable></programlisting>

	    <para>where <replaceable>option</replaceable> can be
	      either <option>shared</option> or
	      <option>static</option>.
	    </para>
	  </step>
	  <step>
	    <title>Install</title>
	    <para>
	      Now, you are ready to run the <command>./make.tcl
		install</command> command to install the resulting
	      files.  This should copy the shared object (like
	      <filename>mod_rivet.so</filename>, if one was
	      successfully created, into Apache's
	      <filename>libexec</filename> directory, as well as
	      install some support scripts and various code.
	    </para>
	  </step>
	</substeps>
      </step>
      <step>
	<title>Apache Configuration Files</title>
	<para>
	  Rivet is relatively easy to configure - we start off by
	  adding the module itself:
	</para>

	<programlisting>LoadModule rivet_module	<replaceable>/usr/lib/apache/1.3/mod_rivet.so</replaceable></programlisting>

	<para>
	  This tells Apache to load the Rivet shared object, wherever
	  it happens to reside on your file system.  Now we have to
	  tell Apache what kind of files are "Rivet" files and how to
	  process them:
	</para>

	<programlisting>AddType application/x-httpd-rivet .rvt
AddType application/x-rivet-tcl .tcl</programlisting>

	<para>
	  These tell Apache to process files with the
	  <filename>.rvt</filename> and <filename>.tcl</filename>
	  extensions as Rivet files.
	</para>
	<para>
	  For other directives that Rivet provides for Apache
	  configuration, please see <xref linkend="directives"/>.
	</para>
      </step>
    </procedure>
  </section>

  <section id="directives">
    <title>Rivet Apache Directives</title>

    <para>
      These directives are used within the Apache httpd server
      configuration files to modify Apache Rivet's behavior.  Their
      precedence is as follows: <command>RivetDirConf</command>,
      <command>RivetUserConf</command>,
      <command>RivetServerConf</command>, meaning that DirConf will
      override UserConf, which will in turn override ServerConf.
    </para>

    <variablelist>
      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <command>RivetServerConf</command>
	    <group choice="req">
	      <arg>CacheSize</arg>
	      <arg>GlobalInitScript</arg>
	      <arg>ChildInitScript</arg>
	      <arg>ChildExitScript</arg>
	      <arg>BeforeScript</arg>
	      <arg>AfterScript</arg>
	      <arg>ErrorScript</arg>
	      <arg>UploadDirectory</arg>
	      <arg>UploadMaxSize</arg>
	      <arg>UploadFilesToVar</arg>
	      <arg>SeperateVirtualInterps</arg>
	    </group>
	  </cmdsynopsis>
	</term>
	<listitem>
	  <para><command>RivetServerConf</command> specifies a global
	    option that is valid for the whole server.  If you have a
	    virtual host, in some cases, the option specified in the
	    virtualhost takes precedence over the 'global' version.
	  </para>
	</listitem>
	<listitem>
	  <variablelist>
	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">CacheSize</arg>
		  <arg><replaceable>size</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Sets the size of the internal page cache, where
		  <option><replaceable>size</replaceable></option> is
		  the number of byte-compiled pages to be cached for
		  future use.  Default is
		  <command>MaxRequestsPerChild</command> / 5, or 50,
		  if <command>MaxRequestsPerChild</command> is 0.
		</para>
		<para>
		  This option is completely global, even when using
		  separate, per-virtual host interpreters.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">GlobalInitScript</arg>
		  <arg><replaceable>script</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Tcl script that is run when each interpreter is
		  initialized. <replaceable><option>script</option></replaceable>
		  is an actual Tcl script, so to run a file, you would
		  do:

		  <programlisting>RivetServerConf GlobalInitScript "source /var/www/foobar.tcl"</programlisting>
		</para>
		<para>
		  This option is ignored in virtual hosts.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">ChildInitScript</arg>
		  <arg><replaceable>script</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Script to be evaluated when each Apache child
		  process is initialized.  This is the recommended
		  place to load modules, create global variables, open
		  connections to other facilities (such as databases)
		  and so on.
		</para>
		<para>
		  In virtual hosts, this script is run in addition to
		  any global childinitscript.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">ChildExitScript</arg>
		  <arg><replaceable>script</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Script to be evaluated when each Apache child
		  process exits.  This is the logical place to clean
		  up resources created in
		  <option>ChildInitScript</option>, if necessary.
		</para>
		<para>
		  In virtual hosts, this script is run in addition to
		  any global childexitscript.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">BeforeScript</arg>
		  <arg><replaceable>script</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Script to be evaluated before each server parsed
		  (.rvt) page.  This can be used to create a standard
		  header, for instance.  It could also be used to load
		  code that you need for every page, if you don't want
		  to put it in a <option>GlobalInitScript</option>
		  <option>ChildInitScript</option> when you are first
		  developing a web site.
		  <note>
		    This code is evaluated at the global level, not
		    inside the request namespace where pages are
		    evaluated.
		  </note>
		</para>
		<para>
		  In virtual hosts, this option takes precedence over
		  the global setting.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">AfterScript</arg>
		  <arg><replaceable>script</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Script to be called after each server parsed (.rvt) page.
		</para>
		<para>
		  In virtual hosts, this option takes precedence over
		  the global setting.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">ErrorScript</arg>
		  <arg><replaceable>script</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  When Rivet encounters an error in a script, it
		  constructs an HTML page with some information about
		  the error, and the script that was being
		  evaluated. If an <option>ErrorScript</option> is
		  specified, it is possible to create custom error
		  pages.  This may be useful if you want to make sure
		  that users never view your source code.
		</para>
		<para>
		  In virtual hosts, this option takes precedence over
		  the global setting.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">UploadDirectory</arg>
		  <arg><replaceable>directory</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>Directory to place uploaded files.</para>
		<para>
		  In virtual hosts, this option takes precedence over
		  the global setting.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">UploadMaxSize</arg>
		  <arg><replaceable>size</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>Maximum size for uploaded files.</para>
		<para>
		  In virtual hosts, this option takes precedence over
		  the global setting.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">UploadFilesToVar</arg>
		  <group choice="req"><arg>yes</arg><arg>no</arg></group>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  This option controls whether it is possible to
		  upload files to a Tcl variable.  If you have a size
		  limit, and don't have to deal with large files, this
		  might be more convenient than sending the data to a
		  file on disk.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">SeperateVirtualInterps</arg>
		  <group choice="req">
		    <arg>yes</arg>
		    <arg>no</arg>
		  </group>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  If on, Rivet will create a separate Tcl interpreter
		  for each Apache virtual host.  This is useful in an
		  ISP type situation where it is desirable to separate
		  clients into separate interpreters, so that they
		  don't accidentally interfere with one another.
		</para>
		<para>This option is, by nature, only available at the
		global level.</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <command>RivetDirConf</command>
	    <group choice="req">
	      <arg>BeforeScript</arg>
	      <arg>AfterScript</arg>
	      <arg>ErrorScript</arg>
	      <arg>UploadDirectory</arg>
	    </group>
	  </cmdsynopsis>
	</term>
	<listitem>
	  <para>
	    These options are the same as for
	    <command>RivetServerConf</command>, except that they are
	    only valid for the directory where they are specified, and
	    its subdirectories.  It may be specified in
	    <command>Directory</command> sections.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <command>RivetUserConf</command>
	    <group choice="req">
	      <arg>BeforeScript</arg>
	      <arg>AfterScript</arg>
	      <arg>ErrorScript</arg>
	      <arg>UploadDirectory</arg>
	    </group>
	  </cmdsynopsis>
	</term>
	<listitem>
	  <para>
	    These options are the same as for
	    <command>RivetServerConf</command>, except that they are
	    only valid for the directory where they are specified, and
	    its subdirectories.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>

  </section>

  <section id="commands">
    <title>Rivet Tcl Commands and Variables</title>


    <refentry>
      <refnamediv>
	<refname>var</refname>
	<refname>var_qs</refname>
	<refname>var_post</refname>
	<refpurpose>get the value of a form variable.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>
	    var
	  </command>
	  <group choice="req">
	    <arg>get</arg>
	    <arg>list</arg>
	    <arg>exists</arg>
	    <arg>number</arg>
	    <arg>all</arg>
	  </group>
	</cmdsynopsis>

	<cmdsynopsis>
	  <command>
	    var_qs
	  </command>
	  <group choice="req">
	    <arg>get</arg>
	    <arg>list</arg>
	    <arg>exists</arg>
	    <arg>number</arg>
	    <arg>all</arg>
	  </group>
	</cmdsynopsis>

	<cmdsynopsis>
	  <command>
	    var_post
	  </command>
	  <group choice="req">
	    <arg>get</arg>
	    <arg>list</arg>
	    <arg>exists</arg>
	    <arg>number</arg>
	    <arg>all</arg>
	  </group>
	</cmdsynopsis>


      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  The <command>var</command> command retrieves information
	  about GET or POST variables sent to the script via client
	  request.  It treats both GET and POST variables the same,
	  regardless of their origin.  Note that there are two
	  additional forms of <command>var</command>:
	  <command>var_qs</command> and <command>var_post</command>.
	  These two restrict the retrieval of information to
	  parameters arriving via the querystring
	  (?foo=bar&amp;bee=bop) or POSTing, respectively.
	</para>
	<variablelist>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>var</command>
		<arg choice="plain">get</arg>
		<arg><replaceable>varname</replaceable></arg>
		<arg><replaceable><optional>default</optional></replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns the value of variable
		<option><replaceable>varname</replaceable></option>
		as a string (even if there are multiple values).  If
		the variable doesn't exist as a GET or POST
		variable, the
		<option><replaceable><optional>default</optional></replaceable></option>
		value is returned, otherwise "" - an empty string -
		is returned.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>var</command>
		<arg choice="plain">list</arg>
		<arg><replaceable>varname</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns the value of variable
		<option><replaceable>varname</replaceable></option> as a
		list, if there are multiple values.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>var</command>
		<arg choice="plain">exists</arg>
		<arg><replaceable>varname</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns 1 if
		<option><replaceable>varname</replaceable></option>
		exists, 0 if it doesn't.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>var</command>
		<arg choice="plain">number</arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns the number of variables.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>var</command>
		<arg choice="plain">all</arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Return a list of variable names and values.
	      </para>
	    </listitem>
	  </varlistentry>
	</variablelist>

	<para>
	  See <xref linkend="variable_access"/>.
	</para>

      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>upload</refname>
	<refpurpose>handle a file uploaded by a client.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>upload</command>
	  <group choice="req">
	    <arg>channel</arg>
	    <arg>save</arg>
	    <arg>data</arg>
	    <arg>exists</arg>
	    <arg>size</arg>
	    <arg>type</arg>
	    <arg>filename</arg>
	  </group>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>The upload command is for file upload manipulation.
	  See the relevant Apache Directives to further configure the
	  behavior of this Rivet feature.</para>


	<variablelist>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>upload</command>
		<arg choice="plain">channel</arg>
		<arg><replaceable>uploadname</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		When given the name of a file upload
		<option><replaceable>uploadname</replaceable></option>,
		returns a Tcl channel that can be used to access the
		uploaded file.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>upload</command>
		<arg choice="plain">save</arg>
		<arg><replaceable>uploadname</replaceable></arg>
		<arg><replaceable>filename</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Saves the
		<option><replaceable>uploadname</replaceable></option> in
		the file
		<option><replaceable>filename</replaceable></option>.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>upload</command>
		<arg choice="plain">data</arg>
		<arg><replaceable>uploadname</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns data uploaded to the server.  This is binary clean
		- in other words, it will work even with files like
		images, executables, compressed files, and so on.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>upload</command>
		<arg choice="plain">size</arg>
		<arg><replaceable>uploadname</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns the size of the file uploaded.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>upload</command>
		<arg choice="plain">type</arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		If the <varname>Content-type</varname> is set, it is
		returned, otherwise, an empty string.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>upload</command>
		<arg choice="plain">filename</arg>
		<arg><replaceable>uploadname</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns the filename on the remote host that uploaded the file.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>upload</command>
		<arg choice="plain">names</arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Returns the variable names, as a list, of all the files
		uploaded.
	      </para>
	    </listitem>
	  </varlistentry>
	</variablelist>

	<para>
	  See <xref linkend="upload"/>.
	</para>


      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>load_response</refname>
	<refpurpose>load form variables into an array.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>load_response</command>
	  <arg><replaceable>arrayName</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	Load any form variables passed to this page into an
	array.
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>load_headers</refname>
	<refpurpose>get client request's headers.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>load_headers</command>
	  <arg><replaceable>array_name</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Load the headers that come from a client request into the
	  provided array name, or use <option>headers</option> if no
	  name is provided.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>load_cookies</refname>
	<refpurpose>get any cookie variables sent by the client.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>load_cookies</command>
	  <arg choice="opt"><replaceable>array_name</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
      </refsect1>
      <para>
	Load the array of cookie variables into the specified
	array name.  Uses array <option>cookies</option> by
	default.
      </para>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>load_env</refname>
	<refpurpose>get the request's environment variables.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>load_env</command>
	  <arg choice="opt"><replaceable>array_name</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>

	<para>
	  Load the array of environment variables into the specified
	  array name.  Uses array <option>::request::env</option> by
	  default.
	</para>
	<para>
	  As Rivet pages are run in the <option>::request</option>
	  namespace, it isn't necessary to qualify the array name
	  for most uses - it's ok to access it as
	  <option>env</option>.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>env</refname> <refpurpose>Loads a single
	"environmental variable" into a Tcl variable.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>env</command>
	  <arg><replaceable>varName</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>

	<para>
	  If it is only necessary to load one environmental variable,
	  this command may be used to avoid the overhead of loading
	  and storing the entire array.
	</para>
      </refsect1>
    </refentry>


    <refentry>
      <refnamediv>
	<refname>include</refname>
	<refpurpose>includes a file into the output stream without modification.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>include</command>
	  <arg><replaceable>filename_name</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Include a file without parsing it for processing tags &lt;?
	  and ?&gt;.  This is the best way to include an HTML file or
	  any other static content.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>parse</refname>
	<refpurpose>parses a Rivet template file.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>parse</command>
	  <arg><replaceable>filename</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Like the Tcl <command>source</command> command, but also
	  parses for Rivet &lt;?  and ?&gt; processing tags.  Using
	  this command, you can use one .rvt file from another.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>headers</refname>
	<refpurpose>set and parse HTTP headers.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>headers</command>
	  <group choice="req">
	    <arg>set</arg>
	    <arg>redirect</arg>
	    <arg>add</arg>
	    <arg>type</arg>
	    <arg>numeric</arg>
	  </group>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  The <command>headers</command> command is for setting and
	  parsing HTTP headers.
	</para>

	<variablelist>

	  <varlistentry>
	    <term><cmdsynopsis>
		<command>headers</command>
		<arg choice="plain">set</arg>
		<arg><replaceable>headername</replaceable></arg>
		<arg><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Set arbitrary header names and values.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>headers</command>
		<arg choice="plain">redirect</arg>
		<arg><replaceable>uri</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Redirect from the current page to a new
		URI. <emphasis>Must</emphasis> be done in the first block
		of TCL code.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>headers</command>
		<arg choice="plain">add</arg>
		<arg><replaceable>headername</replaceable></arg>
		<arg><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>Add text to header
		<varname>headername</varname>.</para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term><cmdsynopsis>
		<command>headers</command>
		<arg choice="plain">type</arg>
		<arg><replaceable>content-type</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		This command sets the <constant>Content-type</constant>
		header returned by the script, which is useful if you wish
		to send content other than HTML with Rivet - PNG or jpeg
		images, for example.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<command>headers</command>
		<arg choice="plain">numeric</arg>
		<arg><replaceable>response code</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>Set a numeric response code, such as 200, 404 or 500.
	      </para>
	    </listitem>
	  </varlistentry>
	</variablelist>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>makeurl</refname>
	<refpurpose>construct url's based on hostname, port.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>makeurl</command>
	  <arg><replaceable>filename</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Create a self referencing URL from a filename.  For example:
	  <programlisting>makeurl /tclp.gif</programlisting>
	  returns
	  <computeroutput>http://[hostname]:[port]/tclp.gif</computeroutput>.
	  where hostname and port are the hostname and port of the
	  server in question.
	</para>
      </refsect1>
    </refentry>


    <refentry>
      <refnamediv>
	<refname>cookie</refname>
	<refpurpose>get and set cookies.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>cookie</command>
	  <arg>set</arg>
	  <arg><replaceable>cookieName</replaceable></arg>
	  <arg><replaceable><optional>cookiValue</optional></replaceable></arg>
	  <arg>-days <replaceable>expireInDays</replaceable></arg>
	  <arg>-hours <replaceable>expireInHours</replaceable></arg>
	  <arg>-minutes <replaceable>expireInMinutes</replaceable></arg>
	  <arg>-expires <replaceable>Wdy, DD-Mon-YYYY HH:MM:SS GMT</replaceable></arg>
	  <arg>-path <replaceable>uriPathCookieAppliesTo</replaceable></arg>
	  <arg>-secure <replaceable>1/0</replaceable></arg>
	</cmdsynopsis>
	<cmdsynopsis>
	  <command>cookie</command>
	  <arg>get</arg>
	  <arg><replaceable>cookieName</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  <command>cookie</command> gets or sets a cookie.  When you
	  get a cookie, the command returns the value of the cookie,
	  or an empty string if no cookie exists.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>clock_to_rfc850_gmt</refname>
	<refpurpose>create a rfc850 time from [clock seconds].</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>clock_to_rfc850_gmt</command>
	  <arg><replaceable>seconds</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Convert an integer-seconds-since-1970 click value to
	  RFC850 format, with the additional requirement that it be
	  GMT only.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>html</refname>
	<refpurpose>construct html tagged text.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>html</command>
	  <arg><replaceable>string</replaceable></arg>
	  <arg rep="repeat"><replaceable>arg</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Print text with the added ability to pass HTML tags
	  following the string.  Example:
	  <programlisting>html "Test" b i</programlisting>
	  produces: <computeroutput>&lt;b&gt;&lt;i&gt;Test&lt;/i&gt;&lt;/b&gt;</computeroutput>
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>incr0</refname>
	<refpurpose>increment a variable or set it to 1 if nonexistant.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>incr0</command>
	  <arg><replaceable>varname</replaceable></arg>
	  <arg><replaceable>num</replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Increment a variable
	  <option><replaceable>varname</replaceable></option> by
	  <option><replaceable>num</replaceable></option>.  If the
	  variable doesn't exist, create it instead of returning an
	  error.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>parray</refname>
	<refpurpose>Tcl's <command>parray</command> with html formatting.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>parray</command>
	  <arg><replaceable>arrayName</replaceable></arg>
	  <arg><replaceable><optional>pattern</optional></replaceable></arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  An html version of the standard Tcl
	  <command>parray</command> command.  Displays the entire
	  contents of an array in a sorted, nicely-formatted way.
	  Mostly used for debugging purposes.
	</para>

      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>abort_page</refname>
	<refpurpose>Stops outputing data to web page, similar in
	  purpose to PHP's <command>die</command> command.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>abort_page</command>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title> <para>This command flushes the
	output buffer and stops the Tcl script from sending any more
	data to the client.  A normal Tcl script might use the
	<command>exit</command> command, but that cannot be used in
	Rivet without actually exiting the apache child
	process!</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>no_body</refname>
	<refpurpose>Prevents Rivet from sending any content.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>no_body</command>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>

	<para>
	  This command is useful for situations where it is necessary
	  to only return HTTP headers and no actual content.  For
	  instance, when returning a 304 redirect.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>escape_string</refname>
	<refpurpose>convert a string into escaped characters.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>escape_string</command>
	  <arg>string</arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Scans through each character in the specified string looking
	  for special characters, escaping them as needed, mapping
	  special characters to a quoted hexadecimal equivalent,
	  returning the result.
	</para>
	<para>
	This is useful for quoting strings that are going to be
	part of a URL.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>escape_sgml_chars</refname>
	<refpurpose>escape special SGML characters in a string.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>escape_sgml_chars</command>
	  <arg>string</arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Scans through each character in the specified string looking
	  for any special (with respect to SGML, and hence HTML) characters
	  from the specified string, and returns the result.  
	  For example, the right angle
	  bracket is escaped to the corrected ampersand gt symbol.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>escape_shell_command</refname>
	<refpurpose>escape shell metacharacters in a string.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>escape_shell_command</command>
	  <arg>string</arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Scans through each character in the specified string looking
	  for any shell metacharacters, such as asterisk, less than and
	  greater than, parens, square brackets, curly brackets, angle 
	  brackets, dollar signs, backslashes, semicolons, ampersands,
	  vertical bars, etc.
	</para>
	<para>
	  For each metacharacter found, it is quoted in the result by
	  prepending it with a backslash, returning the result.
	</para>
      </refsect1>
    </refentry>

    <refentry>
      <refnamediv>
	<refname>unescape_string</refname>
	<refpurpose>unescape escaped characters in a string.</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>unescape_string</command>
	  <arg>string</arg>
	</cmdsynopsis>
      </refsynopsisdiv>

      <refsect1>
	<title>Description</title>
	<para>
	  Scans through each character in the specified string looking
	  for escaped character sequences (characters containing a
	  percent sign and two hexadecimal characters, unescaping them 
	  back to their original character values, as needed, also mapping
	  plus signs to spaces, and returning the result.
	</para>
	<para>
	This is useful for unquoting strings that have been quoted to
	be part of a URL.
	</para>
      </refsect1>
    </refentry>

  </section>

  <section id="examples">
    <title>Examples and Usage</title>

    <para>
      Some examples of Rivet usage follow.  Some prior Tcl knowledge
      is assumed.  If you don't know much Tcl, don't worry, it's easy,
      and there are some good resources available on the web that will
      get you up to speed quickly.  Go to the <link
	linkend="websites">web sites</link> section and have a look.
    </para>

    <example id="hello world">
      <title>Hello World</title>
      <para>
	As with any tool, it's always nice to see something work, so
	let's create a small "Hello World" page.</para>
      <para>
	Assuming you have Apache configured correctly, create a file
	called <filename>hello.rvt</filename> where Apache can find
	it, with the following content:
      </para>
      <programlisting>&hello.rvt;</programlisting>
      <para>
	If you then access it with your browser, you should see a
	blank page with the text "Hello World" (without the quotes) on
	it.
      </para>
    </example>

    <example id="table">
      <title>Generate a Table</title>
      <para>
	In another simple example, we dynamically generate a table:
      </para>
      <programlisting>&table.rvt;</programlisting>
      <para>
	If you read the code, you can see that this is pure Tcl.  We
	could take the same code, run it outside of Rivet, and it
	would generate the same HTML!
      </para>
      <para>
	The result should look something like this:
      </para>
      <graphic fileref="table.png"/>

    </example>

    <example id="variable_access">
      <title>Variable Access</title>
      <para>
	Here, we demonstrate how to access variables set by GET or
	POST operations.
      </para>
      <para>
	Given an HTML form like the following:
      </para>
      <programlisting>&vars.html;</programlisting>
      <para>
	We can use this Rivet script to get the variable values:
      </para>
      <programlisting>&vars.rvt;</programlisting>
      <para>
	The first statement checks to make sure that the
	<varname>boss</varname> variable has been passed to the
	script, and then does something with that information.  If
	it's not present, an error is added to the list of errors.
      </para>
      <para>
	In the second block of code, the variable
	<varname>salary</varname> is fetched, with one more error
	check - because it's a number, it needs to be composed of
	digits.
      </para>
      <para>
	The <varname>boss</varname> variable isn't required to have
	been sent - we set it to "Mr. Burns" if it isn't among the
	information we received.
      </para>
      <para>
	The last bit of variable handing code is a bit trickier.
	Because <varname>skills</varname> is a listbox, and can
	potentially have multiple values, we opt to receive them as a
	list, so that at some point, we could iterate over them.
      </para>
      <para>
	The script then checks to make sure that
	<varname>errlist</varname> is empty and outputting a thankyou
	message.  If <varname>errlist</varname> is not empty, the list
	of errors it contains is printed.
      </para>
    </example>

    <example id="upload">
      <title>File Upload</title>
      <para>
	The following HTML in one file, say,
	<filename>upload.html</filename>
      </para>
      <programlisting>&upload.html;</programlisting>
      <para>
	Can be used with the following Tcl code, in a second file
	(<filename>upload.rvt</filename> for instance)
	in order to create a file upload form.
      </para>
      <programlisting>&upload.rvt;</programlisting>
    </example>

  </section>

  <section id="tcl_packages">
    <title>Rivet Tcl Packages</title>
    <para>
      In addition to the core Apache module, Rivet provides a number
      of Tcl packages that include potentially useful code.
    </para>
    <itemizedlist>

      <listitem>
	<para>commserver is a package providing a server that can be
	used for IPC.  Still experimental.  Requires the comm package
	from tcllib.</para>
      </listitem>

      <listitem>
	<para>dio is a database abstraction layer.</para>
      </listitem>

      <listitem>
	<para>dtcl is a compatibility package for mod_dtcl
	applications.</para>
      </listitem>

      <listitem>
	<para>form - for creating forms.</para>
      </listitem>

      <listitem>
	<para>rivet - some additional, useful routines.</para>
      </listitem>

      <listitem>
	<para>tclrivet</para>
      </listitem>
    </itemizedlist>
  </section>

  <section id="dio">
    <title>DIO - Database Interface Objects</title>
    <refentry>
      <refnamediv>
	<refname>DIO</refname>
	<refpurpose>Database Interface Objects</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>::DIO::handle</command>
	  <arg choice="plain"><replaceable>interface</replaceable></arg>
	  <arg choice="opt"><replaceable>objectName</replaceable></arg>
	  <group choice="opt">
	    <arg>-option</arg>
	    <arg><replaceable>option</replaceable></arg>
	    <arg>-option</arg>
	    <arg><replaceable>option</replaceable></arg>
	    <arg>...</arg>
	  </group>
	</cmdsynopsis>
      </refsynopsisdiv>
      <refsect1>
	<title>Description</title>
	<para>
	  <command>DIO</command> is designed to be a generic,
	  object-oriented interface to SQL databases.  Its main goal
	  is to be as generic as possible, but since not all SQL
	  databases support the exact same syntaxes, keeping code
	  generic between databases is left to the abilities of the
	  programmer.  DIO simply provides a way to keep the Tcl
	  interface generic.
	</para>
	<para>
	  <option>interface</option> - The name of the database
	  interface.  Currently supported interfaces are
	  <option>Postgresql</option> and <option>Mysql</option>.
	</para>
	<para>
	  If <option><replaceable>objectName</replaceable></option> is
	  specified, DIO creates an object of that name.  If there is
	  no <option><replaceable>objectName</replaceable></option>
	  given, DIO will automatically generate a unique object ID
	</para>
      </refsect1>
      <refsect1>
	<title>Options</title>
	<variablelist>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-host</arg>
		<arg choice="opt"><replaceable>hostname</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		The hostname of the computer to connect to.  If none
		is given, DIO assumes the local host.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-port</arg>
		<arg><replaceable>portNumber</replaceable></arg>
	      </cmdsynopsis>
	      <para>The port number to connect to on <option>hostname</option>.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-user</arg>
		<arg><replaceable>username</replaceable></arg>
	      </cmdsynopsis>
	      <para>The username you wish to login to the server as.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-pass</arg>
		<arg><replaceable>password</replaceable></arg>
	      </cmdsynopsis>
	      <para>The password to login to the server with.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-db</arg>
		<arg><replaceable>database</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		The name of the database to connect to.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-table</arg>
		<arg><replaceable>tableName</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		The default table to use when using built-in commands
		for storing and fetching.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-keyfield</arg>
		<arg><replaceable>keyFieldname</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		The default field to use as the primary key when using
		built-in commands for storing and fetching.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-autokey</arg>
		<group>
		  <arg>1</arg>
		  <arg>0</arg>
		</group>
	      </cmdsynopsis>
	      <para>
		If this option is set to 1, DIO will attempt to
		determine an automatic key for
		<option>keyField</option> when storing and fetching.
		In most databases, this requires that the
		<option>sequence</option> also be specified.  In the
		case of MySQL, where sequences do not exist, autokey
		must be used in conjunction with a table which has a
		field specified as AUTO.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain">-sequence</arg>
		<arg><replaceable>sequenceName</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		If DIO is automatically generating keys, it will use
		this sequence as a means to gain a unique number for
		the stored key.</para>
	    </listitem>
	  </varlistentry>
	</variablelist>
      </refsect1>
      <refsect1>
	<title>DIO Object Commands</title>
	<variablelist>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>array</arg>
		<arg><replaceable>request</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Execute <option>request</option> as a SQL query and
		create an array from the first record found.  The
		array is set with the fields of the table and the
		values of the record found.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>autokey</arg>
		<group choice="opt">
		  <arg>value</arg>
		  <arg>boolean</arg>
		</group>
	      </cmdsynopsis>
	      <para>
		Return the current autokey value.  If
		<option>value</option> is specified, it sets a new
		value for the autokey option.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>close</arg>
	      </cmdsynopsis>
	      <para>	      Close the current database connection.  This command is
		automatically called when the DIO object is destroyed.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>db</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current database.  If
		<option>value</option> is specified, it sets a new
		value for the database.  In most cases, the DIO object
		will automatically connect to the new database when
		this option is changed.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>delete</arg>
		<arg><replaceable>key</replaceable></arg>
		<group choice="opt">
		  <arg>-option</arg>
		  <arg><replaceable>option</replaceable></arg>
		  <arg>...</arg>
		</group>
	      </cmdsynopsis>
	      <para>
		Delete a record from the database where the primary
		key matches <option>key</option>.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>destroy</arg>
	      </cmdsynopsis>
	      <para>
		Destroy the DIO object.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>errorinfo</arg>
		<arg choice="opt">value</arg>
	      </cmdsynopsis>
	      <para><option>errorinfo</option> contains the value of
		the last error, if any, to occur while executing a
		request.  When a request fails for any reason, this
		variable is filled with the error message from the SQL
		interface package.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>exec</arg>
		<arg><replaceable>request</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Execute <option>request</option> as an SQL query.
		When the exec command is called, the query is
		executed, and a DIO result object is returned.  From
		there, the result object can be used to obtain
		information about the query status and records in a
		generic way.  See <link linkend="resultobj">Result
		  Object Commands</link>
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>fetch</arg>
		<arg><replaceable>key</replaceable></arg>
		<arg><replaceable>arrayName</replaceable></arg>
		<group choice="opt">
		  <arg>-option</arg>
		  <arg><replaceable>option</replaceable></arg>
		  <arg>...</arg>
		</group>
	      </cmdsynopsis>
	      <para>
		Fetch a record from the database where the primary key
		matches <option>key</option> and store the result in
		an array called <option>arrayName</option>.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>host</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current host value.  If
		<option>value</option> is specified, it sets a new
		value for the host.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>insert</arg>
		<arg><replaceable>arrayName</replaceable></arg>
		<group choice="opt">
		  <arg>-option</arg>
		  <arg><replaceable>option</replaceable></arg>
		  <arg>...</arg>
		</group>
	      </cmdsynopsis>
	      <para>
		Insert fields from <option>arrayName</option> into the specified table in the database.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>keyfield</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current keyfield.  If
		<option>value</option> is specified, it sets a new
		value for the keyfield.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>keys</arg>
		<arg choice="opt"><replaceable>pattern</replaceable></arg>
		<group choice="opt">
		  <arg>-option</arg>
		  <arg><replaceable>option</replaceable></arg>
		  <arg>...</arg>
		</group>
	      </cmdsynopsis>
	      <para>
		Return a list of keys in the database.  If
		<option>pattern</option> is specified, only the keys
		matching will be returned.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>lastkey</arg>
	      </cmdsynopsis>
	      <para>
		Return the last key that was used from
		<option>sequence</option>.  If sequence has not been
		specified, this command returns an empty string.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>list</arg>
		<arg>request</arg>
	      </cmdsynopsis>
	      <para>
		Execute <option>request</option> as a SQL query and
		return a list of the first column of each record
		found.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>nextkey</arg>
	      </cmdsynopsis>
	      <para>Increment <option>sequence</option> and return the
		next key to be used.  If sequence has not been
		specified, this command returns an empty
		string.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>open</arg>
	      </cmdsynopsis>
	      <para>Open the connection to the current database.  This
		command is automatically called from any command which
		accesses the database.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>pass</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current pass value.  If
		<option>value</option> is specified, it sets a new
		value for the password.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>port</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>Return the current port value.  If <option>value</option> is
		specified, it sets a new value for the port.</para>
	    </listitem>
	  </varlistentry>	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>sequence</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current sequence value.  If <option>value</option> is
		specified, it sets a new value for the sequence.
	      </para>
	    </listitem>
	  </varlistentry>	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>store</arg>
		<arg><replaceable>arrayName</replaceable></arg>
		<group choice="opt">
		  <arg>-option</arg>
		  <arg><replaceable>option</replaceable></arg>
		  <arg>...</arg>
		</group>
	      </cmdsynopsis>
	      <para>
		Store <option>arrayName</option> in the database, inserting it if the corresponding record isn't there, or updating it if it is.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>string</arg>
		<arg><replaceable>request</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Execute <option>request</option> as a SQL query and
		return a string containing the first record
		found.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>table</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>Return the current table.  If
		<option>value</option> is specified, it sets a new
		value for the table.</para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>objectName</replaceable></arg>
		<arg>user</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current user value.  If
		<option>value</option> is specified, it sets a new
		value for the user.
	      </para>
	    </listitem>
	  </varlistentry>
	</variablelist>
      </refsect1>
      <refsect1 id="resultobj">
	<title>Result Object Commands</title>
	<variablelist>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>autocache</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current autocache value.  If
		<option>value</option> is specified, it sets a new
		value for autocache.
	      </para>
	      <para>
		If autocache is true, the result object will
		automatically cache rows as you use them.  This means
		that the first time you execute a forall command, each
		row is being cached in the result object itself and
		will no longer need to access the SQL result.
		<emphasis>Default is true</emphasis>.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>cache</arg>
	      </cmdsynopsis>
	      <para>
		Cache the results of the current SQL result in the
		result object itself.  This means that even if the
		database connection is closed and all the results of
		the DIO object are lost, this result object will still
		maintain a cached copy of its records.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>errorcode</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current errorcode value.  If <option>value</option>
		is specified, it sets a new value for errorcode.
	      </para>
	      <para>
		<option>errorcode</option> contains the current code from the
		SQL database which specifies the result of the query
		statement which created this object.  This variable
		can be used to determine the success or failure of a
		query.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>errorinfo</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current errorinfo value.  If <option>value</option>
		is specified, it sets a new value for errorinfo.
	      </para>
	      <para>
		If an error occurred during the SQL query, DIO
		attempts to set the value of <option>errorinfo</option> to the
		resulting error message.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>fields</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current fields value.  If
		<option>value</option> is specified, it sets a new
		value for fields.
	      </para>
	      <para>
		<option>fields</option> contains the list of fields
		used in this query.  The fields are in order of the
		fields retrieved for each row.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>forall</arg>
		<arg><replaceable>-type</replaceable></arg>
		<arg><replaceable>varName</replaceable></arg>
		<arg><replaceable>body</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Execute <option>body</option> over each record in the
		result object.
	      </para>
	      <para>Types:</para>
	      <variablelist>
		<varlistentry>
		  <listitem>
		    <cmdsynopsis>
		      <arg choice="plain">-array</arg>
		    </cmdsynopsis>
		    <para>
		      Create
		      <option><replaceable>varName</replaceable></option>
		      as an array where the indexes are the names of
		      the fields in the table and the values are the
		      values of the current row.
		    </para>
		  </listitem>
		</varlistentry>
		<varlistentry>
		  <listitem>
		    <cmdsynopsis>
		      <arg choice="plain">-keyvalue</arg>
		    </cmdsynopsis>
		    <para>
		      Set
		      <option><replaceable>varName</replaceable></option>
		      to a list containing key-value pairs of fields
		      and values from the current row. (-field value
		      -field value)
		    </para>
		  </listitem>
		</varlistentry>
		<varlistentry>
		  <listitem>
		    <cmdsynopsis>
		      <arg choice="plain">-list</arg>
		    </cmdsynopsis>
		    <para>
		      Set
		      <option><replaceable>varName</replaceable></option>
		      to a list that contains the values of the
		      current row.
		    </para>
		  </listitem>
		</varlistentry>
	      </variablelist>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>next</arg>
		<arg><replaceable>-type</replaceable></arg>
		<arg choice="opt"><replaceable>varName</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Retrieve the next record in the result object.
	      </para>
	      <para>Types:</para>
	      <variablelist>
		<varlistentry>
		  <listitem>
		    <cmdsynopsis>
		      <arg choice="plain">-array</arg>
		    </cmdsynopsis>
		    <para>
		      Create
		      <option><replaceable>varName</replaceable></option>
		      as an array where the indexes are the names of
		      the fields in the table and the values are the
		      values of the current row.
		    </para>
		  </listitem>
		</varlistentry>
		<varlistentry>
		  <listitem>
		    <cmdsynopsis>
		      <arg choice="plain">-keyvalue</arg>
		    </cmdsynopsis>
		    <para>
		      Set
		      <option><replaceable>varName</replaceable></option>
		      to a list containing key-value pairs of fields
		      and values from the current row. (-field value
		      -field value)
		    </para>
		  </listitem>
		</varlistentry>
		<varlistentry>
		  <listitem>
		    <cmdsynopsis>
		      <arg choice="plain">-list</arg>
		    </cmdsynopsis>
		    <para>
		      Set
		      <option><replaceable>varName</replaceable></option>
		      to a list that contains the values of the
		      current row.
		    </para>
		  </listitem>
		</varlistentry>
	      </variablelist>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>numrows</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current numrows value.  If <option>value</option> is
		specified, it sets a new value for numrows.
	      </para>
	      <para>
		<option>numrows</option> is the number of rows in this result.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>resultid</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current resultid value.  If <option>value</option> is
		specified, it sets a new value for resultid.
	      </para>
	      <para>
		<option>resultid</option> in most databases is the result
		pointer which was given us by the database.  This
		variable is not generic and should not really be used,
		but it's there if you want it.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<arg choice="plain"><replaceable>resultObj</replaceable></arg>
		<arg>rowid</arg>
		<arg choice="opt"><replaceable>value</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Return the current rowid value.  If <option>value</option> is
		specified, it sets a new value for rowid.
	      </para>
	      <para>
		<option>rowid</option> contains the number of the
		current result record in the result object.  This
		variable should not really be accessed outside of the
		result object, but it's there if you want it.
	      </para>
	    </listitem>
	  </varlistentry>
	</variablelist>
      </refsect1>
    </refentry>
  </section>


  <section id="diodisplay">
    <title>DIODisplay - Database Interface Objects Display Class</title>
    <refentry>
      <refnamediv>
	<refname>DIODisplay</refname>
	<refpurpose>Database Interface Objects Display Class</refpurpose>
      </refnamediv>

      <refsynopsisdiv>
	<cmdsynopsis>
	  <command>DIODisplay</command>
	  <group>
	    <arg><replaceable>objectName</replaceable></arg>
	    <arg>#auto</arg>
	  </group>
	  <group choice="opt">
	    <arg>-option</arg>
	    <arg><replaceable>option</replaceable></arg>
	    <arg>-option</arg>
	    <arg><replaceable>option</replaceable></arg>
	    <arg>...</arg>
	  </group>
	</cmdsynopsis>
      </refsynopsisdiv>
      <refsect1>
	<title>Description</title>
	<para>
	  DIODisplay is an HTML display class that uses a DIO object
	  to do the database work and a form object to do the
	  displaying.
	</para>
      </refsect1>
      <refsect1>
	<title>Options</title>
	<variablelist>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-DIO</arg>
		<arg choice="plain"><replaceable>dioObject</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		The DIO object to be used in conjunction with this
		display object.  This is a required field.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-cleanup</arg>
		<group>
		  <arg>1</arg>
		  <arg>0</arg>
		</group>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		If cleanup is true, when the display object is shown,
		it will automatically destroy the DIO object, the form
		object and itself. Default is true.
	      </para>
	    </listitem>
	  </varlistentry>


	  <!-- begin transform.html -->

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-confirmdelete</arg>
		<group>
		  <arg>1</arg>
		  <arg>0</arg>
		</group>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		If confirmdelete is true, attempting to delete a
		record from the database first requires that the user
		confirm that they wish to delete it.  If it is false,
		deletion occurs without prompting the user. Defaults
		to true.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-errorhandler</arg>
		<arg choice="plain"><replaceable>procName</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		The name of a procedure to handle errors when they
		occur.  During the processing of requests and pages,
		sometimes unexpected errors can occur.  This procedure
		will handle any errors.  It is called with a single
		argument, the error string.  Use of the Tcl errorInfo
		and errorCode variables is also recommended though.
	      </para>
	      <para>
		If no errorhandler is specified, the handle_error
		method within the Display object will handle the
		error.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-fields</arg>
		<arg choice="plain"><replaceable>fieldList</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		Specify a list of fields to be used in this object.
		The fields list is actually created by using the
		<command>field</command> command to add fields to the
		display, but this option can be useful to sometimes
		over-set the list of fields created.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-form</arg>
		<arg choice="plain"><replaceable>formObject</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		A Rivet form object to use when displaying a form.  If
		one is not specified, the display object will
		automatically create one when it is necessary.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-functions</arg>
		<arg choice="plain"><replaceable>functionList</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		A list of functions to be displayed in the main menu.
		This is a list of functions the user is allowed to
		execute.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-pagesize</arg>
		<arg choice="plain"><replaceable>pageSize</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		How many records to show per page on a search or
		list. Default is 25.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-rowfields</arg>
		<arg choice="plain"><replaceable>fieldList</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		A list of fields to display in each row of a search or
		list.  When a search or list is conducted and the
		resulting rows are displayed, this list will limit
		which fields are displayed.  Default is all fields.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-rowfunctions</arg>
		<arg choice="plain"><replaceable>functionList</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		A list of functions to display in each row of a search
		or list.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-searchfields</arg>
		<arg choice="plain"><replaceable>fieldList</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		A list of fields to allow a user to search by.  This
		list will appear in the main screen as a drop-down box
		of fields the user can search on.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>
	      <cmdsynopsis>
		<arg choice="plain">-title</arg>
		<arg choice="plain"><replaceable>title</replaceable></arg>
	      </cmdsynopsis>
	    </term>
	    <listitem>
	      <para>
		The title of the display object.  This will be output
		as the title of the HTML document.
	      </para>
	    </listitem>
	  </varlistentry>
	</variablelist>


	<refsect2>
	  <title>DIO Display Object Commands</title>


	  <variablelist>
	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">cleanup</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current cleanup value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for the cleanup
		  option.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">delete</arg>
		  <arg choice="plain"><replaceable>key</replaceable></arg>
		</cmdsynopsis>
	      </term>
		<listitem>
		  <para>
		  Delete the specified <option>key</option> from the
		  database.
		</para>
		<para>
		  The default action of this method is to call the DIO
		  object's delete command.  This method can be
		  overridden.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">destroy</arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Destroy the diodisplay object.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">DIO</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current DIO value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for DIO.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">errorhandler</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current errorhandler value.  If
		  <option><replaceable>value</replaceable></option> is specified, it
		  sets a new value for errorhandler.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">fetch</arg>
		  <arg choice="plain"><replaceable>key</replaceable></arg>
		  <arg choice="plain"><replaceable>arrayName</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Fetch the specified <replaceable><option>key</option></replaceable>
		  from the database and store it as an array in
		  <replaceable><replaceable>arrayName</replaceable></replaceable>.
		</para>
		<para>
		  The default of this method is to call the DIO object's fetch command.
		  This method can be overridden.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">field</arg>
		  <arg choice="plain"><replaceable>fieldName</replaceable></arg>
		  <group rep="repeat">
		    <arg choice="plain">-arg</arg>
		    <arg choice="plain"><replaceable>arg</replaceable></arg>
		  </group>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Create a new field object and add it to the display.
		  When a field is added to the display, a new object
		  of the DIODisplayField class is created with its
		  values.  See [FIXME - LINK] DIO Display Fields for
		  options and values.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">fields</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current fields value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for fields.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">form</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current form value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for form.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">function</arg>
		  <arg choice="plain"><replaceable>functionName</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Add a new function to the list of possible
		  functions.  The display object will only execute
		  methods and procs which are defined as functions by
		  the object.  This is to protect the program from
		  executing a different procedure other than what is
		  allowed.  The <command>function</command> command
		  adds a new function to the list of allowable
		  functions.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain"><replaceable>objectName</replaceable></arg>
		  <arg choice="plain">functions</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current functions value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for functions.  See
		  [FIXME - LINK DIO Display Functions] for a list of
		  default functions.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">pagesize</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current form pagesize.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for pagesize.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">rowfields</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current form rowfields.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for rowfields.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">rowfooter</arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Output the footer of a list of rows to the web page.
		</para>
		<para>
		  This method can be overridden.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">rowfunctions</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current rowfunctions value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for rowfunctions.
		  
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">rowheader</arg>
		</cmdsynopsis>
	      </term>
	    <listitem>
	      <para>
		Output the header of a list of rows to the web page.
		By default, this is an HTML table with a top row
		listing the fields in the table.
		</para>
		<para>
		  This method can be overridden.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">searchfields</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current searchfields value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for searchfields.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">show</arg>
		</cmdsynopsis>
	      </term>
	    <listitem>
	      <para>
		Show the display object.
		</para>
		<para>
		  This is the main method of the display class.  It
		  looks for a variable called <varname>mode</varname>
		  to be passed in through a form response and uses
		  that mode to execute the appropriate function.  If
		  mode is not given, the <command>Main</command>
		  function is called.
		</para>
		<para>
		  This function should be called for every page.
		</para>
	      </listitem>
	    </varlistentry>


	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">showform</arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Display the form of the object.
		</para>
		<para>
		  This method displays the form for this display
		  object.  It is used in the <command>Add</command>
		  and <command>Edit</command> methods but can be
		  called separately if needed.
		</para>
		<para>
		  This method can be overridden if the default look of
		  a form needs to be changed.  By default, the form
		  displayed is simply the fields in a table, in order.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">showrow</arg>
		  <arg choice="plain"><replaceable>arrayName</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Display a single row of a resulting list or search.
		</para>
		<para>
		  This method is used to display a single row while
		  displaying the result of a list or search.
		  <option><replaceable>arrayName</replaceable></option>
		  is a fetched array of the record.
		</para>
		<para>
		  This method can be overriden if the default look of
		  a row needs to be changed.  By default, each row is
		  output as a table row with each field as a table
		  data cell.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">showview</arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Display the view of the object.
		</para>
		<para>
		  This method displays the view for this display
		  object.  It is used in the
		  <command>Details</command> methods but can be
		  called separately if needed.
		</para>
		<para>
		  This method can be overridden if the default look of
		  a view needs to be changed.  By default, the view
		  displayed is simply the fields in a table, in order.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">store</arg>
		  <arg choice="plain"><replaceable>arrayName</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Store the specified
		  <option><replaceable>arrayName</replaceable></option>
		  in the database.
		</para>
		<para>
		  The default of this method is to call the DIO
		  object's store command.  This method can be
		  overridden.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">text</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current text value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for text.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">title</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current title value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for title.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">type</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current type value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for type.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <command><replaceable>objectName</replaceable></command>
		  <arg choice="plain">value</arg>
		  <arg><replaceable>value</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  Return the current value value.  If
		  <option><replaceable>value</replaceable></option> is
		  specified, it sets a new value for value.
		</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>
	</refsect2>

	<refsect2>
	  <title>DIO Display Functions</title>
	  <para>
	    These functions are called from the
	    <command>show</command> method when a form response
	    variable called <varname>mode</varname> is set.  If no
	    mode has been set, the default mode is
	    <command>Main</command>.  The show method will handle
	    the necessary switching of functions.  The show method
	    also handles checking to make sure the function given is a
	    true function.  If not, an error message is displayed.
	    New functions can be added as methods or by use of the
	    <command>function</command> command, and any of the
	    default functions can be overridden with new methods to
	    create an entirely new class.  These are the default
	    functions provided.
	  </para>

	  <variablelist>
	    <varlistentry>
	      <term><command>Add</command></term>
	      <listitem>
		<para>
		  Show a form that allows the user to add a new entry
		  to the database.  This function calls
		  <command>showform</command> to display the form
		  for adding the entry.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>Cancel</command></term>
	      <listitem>
		<para>
		  The <command>Cancel</command> function does nothing
		  but redirect back to the <command>Main</command>
		  function.  This is handy for forms which have a
		  cancel button to point to.
		</para>
	      </listitem>
	    </varlistentry>


	    <varlistentry>
	      <term><command>Delete</command></term>
	      <listitem>
		<para>
		  If <varname>confirmdelete</varname> is true (the
		  default), the <command>Delete</command> function
		  will ask the user if they're sure they want to
		  delete the record from the database.  If
		  <varname>confirmdelete</varname> is false, or if the
		  user confirms they wish to delete, this function
		  calls the <command>DoDelete</command> function to do
		  the actual deletion of a record.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>Details</command></term>
	      <listitem>
		<para>
		  Display the view of a single record from the database.  This function calls
		  the <command>showview</command> method to display a single record from the database.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>DoDelete</command></term>
	      <listitem>
		<para>
		  This function actually deletes a record from the
		  database.  Once it has deleted the record, it
		  redirects the user back to the
		  <command>Main</command> function.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>Edit</command></term>
	      <listitem>
		<para>
		  Show a form that allows the user to edit an existing
		  entry to the database.  This function calls
		  <command>showform</command> to display the form for
		  editing the entry and fills in the fields with the
		  values retrieved from the database.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>List</command></term>
	      <listitem>
		<para>
		  This function lists the entires contents of the
		  database.  Each record is output in a row using the
		  <command>showrow</command> method.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>Main</command></term>
	      <listitem>
		<para>
		  This function is the main function of the display
		  object.  If there is no mode, or once most commands
		  complete, the user will be redirected to this
		  function.  The default <command>Main</command>
		  function displays a list of functions the user can
		  execute, a list of searchfields the user can search
		  on, and a query field.  This query field is used by
		  all of the other functions to determine what the
		  user is trying to find.
		</para>
		<para>
		  In the case of a <command>search</command>, query
		  specifies what string the user is looking for in the
		  specified search field.  In the case of
		  <command>delete</command>,
		  <command>details</command> or
		  <command>edit</command>, the query specifies the
		  database key to access.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>Save</command></term>
	      <listitem>
		<para>
		  This function saves any data passed to using the
		  <command>store</command> method.  This is primarily
		  used by the <command>add</command> and
		  <command>edit</command> commands to store the
		  results of the form the user has filled out.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><command>Search</command></term>
	      <listitem>
		<para>
		  This function searches the database for any row
		  whose <varname>searchBy</varname> field matches
		  <varname>query</varname>. Once any number of records
		  are found, <command>Search</command> displays the
		  results in rows.
		</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>
	</refsect2>

	<refsect2>
	  <title>DIO Display Fields</title>
	  <para>
	    Display fields are created with the
	    <command>field</command> command of the DIODisplay object.
	    Each field is created as a new DIODisplayField object or
	    as a subclass of DIODisplayField.  The standard form
	    fields use the standard field class, while specialized
	    field types use a class with different options but still
	    supports all of the same commands and values a generic
	    field does.
	  </para>

	  <cmdsynopsis>
	    <command><replaceable>displayObject</replaceable></command>
	    <arg choice="plain">field</arg>
	    <arg
	    choice="plain"><replaceable>fieldname</replaceable></arg>
	    <group choice="opt" rep="repeat">
	      <arg choice="plain">-option</arg>
	      <arg choice="plain"><replaceable>option</replaceable></arg>
	    </group>
	  </cmdsynopsis>

	  <para>
	    These are the standard options supported by field types:
	  </para>

	  <variablelist>
	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">-formargs</arg>
		  <arg choice="plain"><replaceable>arguments</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  When a field is created, any argument which is not a
		  standard option is assumed to be an argument passed
		  to the form object when the field is shown in a
		  form.  These arguments are all appended to the
		  <varname>formargs</varname> variable.  You can use
		  this option to override or add options after the
		  initial creation of an object
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">-readonly</arg>
		  <group>
		    <arg>1</arg>
		    <arg>0</arg>
		  </group>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  If <varname>readonly</varname> is set to true, the
		  field will not display a form entry when displaying
		  in a form.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">-text</arg>
		  <arg choice="plain"><replaceable>text</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  The text displayed next to the form or view field.
		  By default, DIODisplay tries to figure out a pretty
		  way to display the field name.  This text will
		  override that default and display whatever is
		  specified.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>
		<cmdsynopsis>
		  <arg choice="plain">-type</arg>
		  <arg choice="plain"><replaceable>fieldType</replaceable></arg>
		</cmdsynopsis>
	      </term>
	      <listitem>
		<para>
		  The type of field this is.  This type is used when
		  creating the field in the form object.
		  <option><replaceable>fieldType</replaceable></option>
		  can be any of the accepted form field types.  See
		  [FIXME - LINK DIO Field Types] for a list of types
		  available.
		</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>

	  <para>
	    All other arguments, unless specified in an individual
	    field type, are passed directly to the form object when
	    the field is created.  So, you can pass
	    <option>-size</option> or <option>-maxsize</option> to
	    specify the length and maximum length of the field entry.
	    Or, if type were textarea, you could define
	    <option>-rows</option> and <option>-cols</option> to
	    specify its row and column count.
	  </para>
	</refsect2>
	<refsect2>
	  <title>DIO Display Field Types</title>
	  <para>
	    The following is a list of recognized field types by
	    DIODisplay.  Some are standard HTML form fields, and
	    others are DIODisplay fields which execute special actions
	    and functions.
	  </para>
	</refsect2>
      </refsect1>
    </refentry>
  </section>



  <section id="session_package">
    <title>Session Package</title>
    <section>
      <title>Introduction</title>
      <para>
	This is session management code.  It provides an interface
	to allow you to generate and track a browser's visit as a
	"session", giving you a unique session ID and an interface
	for storing and retrieving data for that session on the
	server.
      </para>

      <para>
	This is an alpha/beta release -- documentation is not in
	final form, but everything you need should be in this file.
      </para>

      <para>
	Using sessions and their included ability to store and
	retrieve session-related data on the server, programmers can
	generate more secure and higher-performance websites.  For
	example, hidden fields do not have to be included in forms
	(and the risk of them being manipulated by the user
	mitigated) since data that would be stored in hidden fields
	can now be stored in the session cache on the server.  Forms
	are then faster since no hidden data is transmitted --
	hidden fields must be sent twice, once in the form to the
	broswer and once in the response from it.
      </para>

      <para>
	Robust login systems, etc, can be built on top of this code.
      </para>
    </section>

    <section>
      <title>Requirements</title>


	<para>
	  Rivet.  Currently has only been tested with Postgresql.
	  All DB interfacing is done through DIO, though, so it
	  should be relatively easy to add support for other
	  databases.
	</para>
      </section>

      <section>
	<title>Preparing To Use It</title>

	<para>Create the tables in your SQL server.  With Postgres,
	  do a <command>psql www</command> or whatever DB you
	  connect as, then a backslash-i on
	  <filename>session-create.sql</filename></para>

	<para>(If you need to delete the tables, use <filename>session-drop.sql</filename>)</para>

	<para>The session code by default requires a DIO handle
	  called <varname>DIO</varname> (the name of which can be
	  overridden).  We get it by doing a</para>

<programlisting>
  RivetServerConf ChildInitScript "package require DIO"
  RivetServerConf ChildInitScript "::DIO::handle Postgresql DIO -user www"
</programlisting>

      </section>

      <section>
	<title>Example Usage</title>

	<para>In your httpd.conf, add:</para>

	<programlisting>RivetServerConf ChildInitScript "package require Session; Session SESSION"</programlisting>

	<para>
	  This tells Rivet you want to create a session object named
	  SESSION in every child process Apache creates.</para>

	<para>
	  You can configure the session at this point using numerous
	  key-value pairs (which are defined later in this doc).
	  Here's a quick example:</para>

	<programlisting>RivetServerConf ChildInitScript "package require Session; Session SESSION \
  -cookieLifetime 120 -debugMode 1"</programlisting>

	<para>
	  Turn debugging on <option>-debugMode 1</option> to figure
	  out what's going on -- it's really useful, if
	  verbose.</para>

	<para>
	  In your .rvt file, when you're generating the &lt;HEAD&gt;
	  section:
	</para>

	<programlisting>SESSION activate</programlisting>

	<para>
	  Activate handles everything for you with respect to
	  creating new sessions, and for locating, validating, and
	  updating existing sessions.  Activate will either locate
	  an existing session, or create a new one.  Sessions will
	  automatically be refreshed (their lifetimes extended) as
	  additional requests are received during the session, all
	  under the control of the key-value pairs controlling the
	  session object.
	</para>
      </section>

      <section>
	<title>Using Sessions From Your Code</title>

	<para>The main methods your code will use are:</para>

	<variablelist>
	  <varlistentry>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION</command> <command>id</command>
	      </cmdsynopsis>
	      <para>
		After doing a <command>SESSION activate</command>,
		this will return a 32-byte ASCII-encoded random
		hexadecimal string.  Every time this browser comes
		to us with a request within the timeout period, this
		same string will be returned (assuming they have
		cookies enabled).
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION</command>
		<command>is_new_session</command>
	      </cmdsynopsis>
	      <para>returns 1 if it's a new session or 0 if it has
		previously existed (i.e. it's a zero if this request
		represents a "return" or subsequent visit to a
		current session.)</para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION new_session_reason</command></cmdsynopsis>
	      <para>
		This will return why this request is the first
		request of a new session, either "no_cookie" saying
		the browser didn't give us a session cookie,
		"no_session" indicating we got a cookie but couldn't
		find it in our session table, or "timeout" where
		they had a cookie and we found the matching session
		but the session has timed out.
	      </para>
	    </listitem>
	  </varlistentry>
	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION store</command>
		<arg><replaceable>packageName</replaceable></arg>
		<arg><replaceable>key</replaceable></arg>
		<arg><replaceable>data</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Given the name of a package, a key, and some data.
		Stores the data in the rivet session cache table.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION fetch</command>
		<arg><replaceable>packageName</replaceable></arg>
		<arg><replaceable>key</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Given a package name and a key, return the data
		stored by the store method, or an empty string if
		none was set.  (Status is set to the DIO error that
		occurred, it can be fetched using the status
		method.)
	      </para>
	    </listitem>
	  </varlistentry>
	</variablelist>
      </section>

      <section>
	<title>Session Configuration Options</title>

	<para>The following key-value pairs can be specified when a
	  session object (like SESSION above) is created:</para>

	<variablelist>

	  <varlistentry>
	    <term><option>sessionLifetime</option></term>

	    <listitem>
	      <para>how many seconds the session will live for.
		7200 == 2 hours
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>sessionRefreshInterval</term>
	    <listitem>
	      <para>
		If a request is processed for a browser that
		currently has a session and this long has elapsed
		since the session update time was last updated,
		update it.  900 == 15 minutes.  so if at least 15
		minutes has elapsed and we've gotten a new request
		for a page, update the session update time,
		extending the session lifetime (sessions that are in
		use keep getting extended).
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>cookieName</term>
	    <listitem>
	      <para></para>
	      name of the cookie stored on the user's web browser
	      default rivetSession
	    </listitem>
	  </varlistentry>

	  <varlistentry><term>dioObject</term> 
	    <listitem>
	      <para>
		The name of the DIO object we'll use to access the
		database (default DIO)
	      </para>
	    </listitem></varlistentry>

	  <varlistentry><term>gcProbability</term>
	    <listitem>
	      <para>
		The probability that garbage collection will occur
		in percent.  (default 1%, i.e. 1)</para></listitem></varlistentry>

	  <varlistentry><term>gcMaxLifetime</term>
		<listitem><para>the number of seconds after which
		data will be seen as "garbage" and cleaned up --
		defaults to 1 day (86400)</para></listitem></varlistentry>

	  <varlistentry><term>refererCheck</term>
		<listitem><para>The substring you want to check each
		HTTP referer for.  If the referer was sent by the
		browser and the substring is not found, the session
		will be deleted. (not coded yet)</para></listitem></varlistentry>

	  <varlistentry><term>entropyFile</term> <listitem><para>The
		name of a file that random binary data can be read
		from.  (<filename>/dev/urandom</filename>) Data will
		be used from this file to help generate a
		super-hard-to-guess session ID.</para></listitem></varlistentry>

	  <varlistentry><term>entropyLength</term>
		<listitem><para>The number of bytes which will be
		read from the entropy file.  If 0, the entropy file
		will not be read (default 0)</para></listitem></varlistentry>

	  <varlistentry><term>scrambleCode</term> <listitem><para>
		Set the scramble code to something unique for the
		site or your app or whatever, to slightly increase
		the unguessability of session ids (default "some
		random string")</para></listitem></varlistentry>

	  <varlistentry><term>cookieLifetime</term>
		<listitem><para>The lifetime of the cookie in
		minutes.  0 means until the browser is closed (I
		think). (default 0)</para></listitem></varlistentry>

	  <varlistentry><term>cookiePath</term> <listitem><para>The
		webserver subpath that the session cookie applies to
		(defaults to
		<filename>/</filename>)</para></listitem></varlistentry>

	  <varlistentry><term>cookieDomain</term>
	  <listitem><para>The domain to set in the session cookie
	  (FIXME - not coded yet)</para></listitem></varlistentry>

	  <varlistentry><term>cookieSecure</term>
		<listitem><para>Specifies whether the cookie should
		only be sent over secure connections, 0 = any, 1 =
		secure connections only (default
		0)</para></listitem></varlistentry>

	  <varlistentry><term>sessionTable</term>
		<listitem><para>The name of the table that session
		info will be stored in (default
		<varname>rivet_session</varname>)</para></listitem></varlistentry>

	  <varlistentry><term>sessionCacheTable</term>
		<listitem><para>The name of the table that contains
		cached session data (default
		<varname>rivet_session_cache</varname>)</para></listitem></varlistentry>

	  <varlistentry><term>debugMode</term> <listitem><para>Set
		debug mode to 1 to trace through and see the session
		object do its thing (default 0)</para></listitem></varlistentry>

	  <varlistentry><term>debugFile</term> <listitem><para>The
		file handle that debugging messages will be written
		to (default
		<varname>stdout</varname>)
	      </para>
	    </listitem>
	  </varlistentry>

	</variablelist>
      </section>

      <section>
	<title>Session Methods</title>

	<para>
	  The following methods can be invoked to find out
	  information about the current session, store and fetch
	  server data identified with this session, etc:
	</para>

	<variablelist>
	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION status</command></cmdsynopsis>
	      <para>
		Return the status of the last operation
	      </para>
	    </listitem>
	  </varlistentry>


	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION id</command></cmdsynopsis>
	      <para>
		Get the session ID of the current browser.  Returns
		an empty string if there's no session (will not
		happen is SESSION activate has been issued.)
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION new_session_reason</command>
	      </cmdsynopsis>
	      <para>
		Returns the reason why there wasn't a previous
		session, either "no_cookie" saying the browser
		didn't give us a session cookie, "no_session"
		indicating we got a cookie but couldn't find it in
		the session table, or "timeout" when we had a cookie
		and a session but the session had timed out.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION store</command>
		<arg><replaceable>packageName</replaceable></arg>
		<arg><replaceable>key</replaceable></arg>
		<arg><replaceable>data</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Given a package name, a key string, and a data
		string, store the data in the rivet session
		cache.
	      </para>
	    </listitem>
	  </varlistentry>


	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION fetch</command>
		<arg><replaceable>packageName</replaceable></arg>
		<arg><replaceable>key</replaceable></arg>
	      </cmdsynopsis>
	      <para>
		Given a package name and a key, return the data
		stored by the store method, or an empty string if
		none was set.  Status is set to the DIO error that
		occurred, it can be fetched using the status
		method.
	      </para>
	    </listitem></varlistentry>

	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION delete</command></cmdsynopsis>

	      <para>
		Given a user ID and looking at their IP address we
		inherited from the environment (thanks, Apache),
		remove them from the session table.  (the session
		table is how the server remembers stuff about
		sessions). If the session ID was not specified the
		current session is deleted.
	      </para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term></term>
	    <listitem>
	      <cmdsynopsis>
		<command>SESSION activate</command></cmdsynopsis>

	      <para>
		Find and validate the session ID if they have one.
		If they don't have one or it isn't valid (timed out,
		etc), create a session and drop a cookie on
		them.
	      </para>
	    </listitem>
	  </varlistentry></variablelist>
      </section>

      <section>
	<title>Getting Additional Randomness From The Entropy File</title>

	<programlisting>RivetServerConf ChildInitScript "Session SESSION -entropyFile /dev/urandom \
  -entropyLength 10 -debugMode 1"</programlisting>

	<para>
	  This options say we want to get randomness from an entropy
	  file (random data pseudo-device) of /dev/urandom, to get ten
	  bytes of random data from that entropy device, and to turn
	  on debug mode, which will cause the SESSION object to output
	  all manner of debugging information as it does stuff.  This
	  has been tested on FreeBSD and appears to work.
      </para>
    </section>
  </section>

  <section id="help">
    <title>Resources - How to Get Help</title>

    <section>
      <title>Mailing Lists</title>
      <para>
	The Rivet mailing list is the first place you should turn for
	help, if you haven't found the solution to your problem in the
	documentation.  Send email to
	<email>rivet-dev@tcl.apache.org</email>.  If you have a
	question, idea, or comment about the Rivet code itself, please
	send us email at <email>rivet-dev@tcl.apache.org</email>.  To
	subscribe to either list, post email to
	<email>rivet-<replaceable>list</replaceable>-subscribe@tcl.apache.org</email>,
	where <replaceable>list</replaceable> is either dev or user.
	Currently, dev is the preferred list to use.
      </para>
      <para>
	The mailing list archives are available at <ulink
	  url="http://mail-archives.apache.org/eyebrowse/SummarizeList?listId=118"/>
      </para>
    </section>

    <section>
      <title>Newsgroup</title>
      <para>
	The <ulink url="news:comp.lang.tcl"/> newsgroup is a good
	place to ask about Tcl questions in general.  Rivet developers
	also follow the newsgroup, but it's best to ask Rivet-specific
	questions on the Rivet list.
      </para>
    </section>

    <section id="websites">
      <title>Web Sites</title>

      <para>
	There are several web sites that cover Apache and Tcl
	extensively.
      </para>
      <itemizedlist>
	<listitem>
	  <para>
	    <ulink url="http://tcl.apache.org"/> is the home for the
	    Apache Tcl project.  Go there for the latest versions of
	    our software (if you aren't reading these pages off of the
	    site!).
	  </para>
	</listitem>
	<listitem>
	  <para>
	    <ulink url="http://httpd.apache.org/docs/"/> is the first
	    place to go for questions about the Apache web server.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    <ulink url="http://www.tcl.tk"/> is the canonical site
	    for Tcl information.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    <ulink url="http://wiki.tcl.tk"/> is the Tcl'ers Wiki, a
	    free-form place to search for answers and ask for help.
	  </para>
	</listitem>
      </itemizedlist>
    </section>

    <section>
      <title>Bug Tracking System</title>

      <para>
	Apache Rivet uses the Apache Bug Tracking system at <ulink
	  url="http://issues.apache.org/bugzilla/"></ulink>.  Here,
	you can report problems, or check and see if existing issues
	are already known and being dealt with.
      </para>
    </section>

    <section>
      <title>IRC</title>

      <para>
        Occasionally, someone from the Rivet team is on IRC at
        irc.freenode.net, channel #tcl.
      </para>
    </section>

    <section>
      <title>Editing Rivet Template Files</title>
      <para>
	Rivet makes available code for two popular editors,
	<application>emacs</application> and
	<application>vim</application> to facilitate the editing of
	Rivet template files.  The key concept is that the editor is
	aware of the &lt;? and ?&gt; tags and switches back and forth
	between Tcl and HTML modes as the cursor moves.  These files,
	<filename>two-mode-mode.el</filename> and
	<filename>rvt.vim</filename> are available in the
	<filename>contrib/</filename> directory.
      </para>
    </section>


  </section>

  <section id="internals">
    <title>Rivet Internals</title>
    <para>
      This section easily falls out of date, as new code is added, old
      code is removed, and changes are made.  The best place to look
      is the source code itself.  If you are interested in the changes
      themselves, <command>cvs</command> can provide you with
      information about what has been happening with the code.
    </para>
    <section>
      <title>Initialization</title>
      <para>
	When Apache is started, (or when child Apache processes are
	started if a threaded Tcl is used),
	<function>Rivet_InitTclStuff</function> is called, which
	creates a new interpreter, or one interpreter per virtual
	host, depending on the configuration. It also initializes
	various things, like the <structname>RivetChan</structname>
	channel system, creates the Rivet-specific Tcl commands, and
	executes Rivet's <filename>init.tcl</filename>.  The caching
	system is also set up, and if there is a
	<command>GlobalInitScript</command>, it is run.
      </para>
    </section>
    <section>
      <title>RivetChan</title>
      <para>
	The <structname>RivetChan</structname> system was created in
	order to have an actual Tcl channel that we could redirect
	standard output to.  This lets us use, for instance, the
	regular <command>puts</command> command in .rvt pages.  It
	works by creating a channel that buffers output, and, at
	predetermined times, passes it on to Apache's IO system.
	Tcl's regular standard output is replaced with an instance of
	this channel type, so that, by default, output will go to the
	web page.
      </para>
    </section>
    <section>
      <title>The <command>global</command> Command</title>
      <para>
	Rivet aims to run standard Tcl code with as few surprises as
	possible.  At times this involves some compromises - in this
	case regarding the <command>global</command> command.  The
	problem is that the command will create truly global
	variables.  If the user is just cut'n'pasting some Tcl code
	into Rivet, they most likely just want to be able to share the
	variable in question with other procs, and don't really care
	if the variable is actually persistant between pages.  The
	solution we have created is to create a proc
	<command>::request::global</command> that takes the place of
	the <command>global</command> command in Rivet templates.  If
	you really need a true global variable, use either
	<command>::global</command> or add the :: namespace qualifier
	to variables you wish to make global.
      </para>
    </section>
    <section>
      <title>Page Parsing, Execution and Caching</title>
      <para>
	When a Rivet page is requested, it is transformed into an
	ordinary Tcl script by parsing the file for the &lt;? ?&gt;
	processing instruction tags.  Everything outside these tags
	becomes a large <command>puts</command> statement, and
	everything inside them remains Tcl code.
      </para>
      <para>
	Each .rvt file is evaluated in its own
	<constant>::request</constant> namespace, so that it is not
	necessary to create and tear down interpreters after each
	page.  By running in its own namespace, though, each page will
	not run afoul of local variables created by other scripts,
	because they will be deleted automatically when the namespace
	goes away after Apache finishes handling the request.
      <note>
	    One current problem with this system is that while
	    variables are garbage collected, file handles are not, so
	    that it is very important that Rivet script authors make
	    sure to close all the files they open.
      </note>
      </para>
      <para>
	After a script has been loaded and parsed into it's "pure Tcl"
	form, it is also cached, so that it may be used in the future
	without having to reload it (and re-parse it) from the disk.
	The number of scripts stored in memory is configurable.  This
	feature can significantly improve performance.
      </para>
    </section>

    <section>
      <title>Debugging Rivet and Apache</title>
      <para>
	If you are interested in hacking on Rivet, you're welcome to
	contribute!  Invariably, when working with code, things go
	wrong, and it's necessary to do some debugging.  In a server
	environment like Apache, it can be a bit more difficult to
	find the right way to do this.  Here are some techniques to
	try.
      </para>
      <para>
	The first thing you should know is that Apache can be launched
	as a <emphasis>single process</emphasis> with the
	<option>-X</option> argument:</para>
      <programlisting>httpd -X</programlisting>.
      <para>
	On Linux, one of the first things to try is the system call
	tracer, <command>strace</command>.  You don't even have to
	recompile Rivet or Apache for this to work.
      </para>

      <programlisting>strace -o /tmp/outputfile -S 1000 httpd -X</programlisting>

      <para>This command will run httpd in the system call tracer,
	which leaves its output (there is potentially a lot of it) in
	<filename>/tmp/outputfile</filename>.  The <option>-S</option>
	option tells <command></command>strace to only record the
	first 1000 bytes of a syscall.  Some calls such as
	<function>write</function> can potentially be much longer than
	this, so you may want to increase this number.  The results
	are a list of all the system calls made by the program.  You
	want to look at the end, where the failure presumably occured,
	to see if you can find anything that looks like an error.  If
	you're not sure what to make of the results, you can always
	ask on the Rivet development mailing list.
      </para>

      <para>
	If <command>strace</command> (or its equivalent on your
	operating system) doesn't answer your question, it may be time
	to debug Apache and Rivet.  To do this, you will need to run
	the <command>./configure.tcl</command> script with the
	<option>-enable-symbols</option> option, and recompile.
      </para>
      <para>
	Since it's easier to debug a single process, we'll still run
	Apache in single process mode with -X:
      </para>

      <programlisting>
@ashland [~] $ gdb /usr/sbin/apache.dbg
GNU gdb 5.3-debian
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "powerpc-linux"...
(gdb) run -X
Starting program: /usr/sbin/apache.dbg -X
[New Thread 16384 (LWP 13598)]
.
.
.
      </programlisting>

      <para>
	When your apache session is up and running, you can request a
	web page with the browser, and see where things go wrong (if
	you are dealing with a crash, for instance).  A helpful
	<command>gdb</command> tutorial is available here: <ulink
	  url="http://www.delorie.com/gnu/docs/gdb/gdb_toc.html"></ulink>
      </para>

    </section>

  </section>
  <section id="upgrading">
    <title>Upgrading from mod_dtcl or NeoWebScript</title>
    <para>
      Rivet is a break from the past, in that we, the authors, have
      attempted to take what we like best about our past efforts, and
      leave out or change things we no longer care for.  Backwards
      compatibility was not a primary goal when creating Rivet, but we
      do provide this information which may be of use to those wishing
      to upgrade from mod_dtcl or NWS installations.
    </para>
    <section>
      <title>mod_dtcl</title>
      <para>
	Rivet was originally based on the dtcl code, but it has
	changed (improved!) quite a bit.  The concepts remain the
	same, but many of the commands have changed.
      </para>
    </section>
    <section>
      <title>NeoWebScript</title>
      <para>TODO</para>
    </section>
  </section>
</article>