=encoding utf8

=head1 NAME

XML::Compile::Transport - base class for XML transporters

=head1 INHERITANCE

 XML::Compile::Transport
   is a XML::Compile::SOAP::Extension

 XML::Compile::Transport is extended by
   XML::Compile::Transport::SOAPHTTP
   XML::Compile::Transport::SOAPHTTP_AnyEvent

=head1 SYNOPSIS

 use XML::Compile::Transport::SOAPHTTP;
 my $trans  = XML::Compile::Transport::SOAPHTTP->new(...);
 my $call   = $trans->compileClient(...);

 my ($xmlout, $trace) = $call->($xmlin);
 my $xmlout = $call->($xmlin);   # when no trace needed

=head1 DESCRIPTION

This module defines the exchange of (XML) messages. The module does not
known how to parse or compose XML, but only worries about the transport
aspects.

On the moment, there are three transporter implementations:

=over 4

=item L<XML::Compile::Transport::SOAPHTTP|XML::Compile::Transport::SOAPHTTP>

implements an synchronous message exchange; the library waits for an
answer before it returns to the user application. The information is
exchanged using HTTP with SOAP encapsulation (SOAP also defines a
transport protocol over HTTP without encapsulation)

=item L<XML::Compile::Transport::SOAPHTTP_AnyEvent|XML::Compile::Transport::SOAPHTTP_AnyEvent>

Event-driven implementation, based on AnyEvent.  The user provides a
callback to handle responses. Many queries can be spawned in parallel,
in a single process.  Find this in a separate distribution.

=item XML::Compile::Transport::SOAPHTTP_MojoUA

Event-driven implementation,  which fits in the Mojolicious infrastructure.
Find this in a separate distribution.

=back

Extends L<"DESCRIPTION" in XML::Compile::SOAP::Extension|XML::Compile::SOAP::Extension/"DESCRIPTION">.
 
=head1 METHODS

Extends L<"METHODS" in XML::Compile::SOAP::Extension|XML::Compile::SOAP::Extension/"METHODS">.
 
=head2 Constructors

Extends L<"Constructors" in XML::Compile::SOAP::Extension|XML::Compile::SOAP::Extension/"Constructors">.
 
=over 4

=item XML::Compile::Transport-E<gt>B<new>(%options)

 -Option --Default
  address  'http://localhost'
  charset  'UTF-8'

=over 2

=item address => URI|ARRAY-of-URI

One or more URI which represents the servers.

=item charset => STRING

=back

=back

=head2 WSDL11

Extends L<"WSDL11" in XML::Compile::SOAP::Extension|XML::Compile::SOAP::Extension/"WSDL11">.
 
=over 4

=item $obj-E<gt>B<wsdl11Init>($wsdl, $args)

=item XML::Compile::Transport-E<gt>B<wsdl11Init>($wsdl, $args)

Inherited, see L<XML::Compile::SOAP::Extension/"WSDL11">

=back

=head2 SOAP11

Extends L<"SOAP11" in XML::Compile::SOAP::Extension|XML::Compile::SOAP::Extension/"SOAP11">.
 
=over 4

=item $obj-E<gt>B<soap11ClientWrapper>($operation, $call, $args)

Inherited, see L<XML::Compile::SOAP::Extension/"SOAP11">

=item $obj-E<gt>B<soap11HandlerWrapper>($operation, $callback, $args)

Inherited, see L<XML::Compile::SOAP::Extension/"SOAP11">

=item $obj-E<gt>B<soap11OperationInit>($operation, $args)

=item XML::Compile::Transport-E<gt>B<soap11OperationInit>($operation, $args)

Inherited, see L<XML::Compile::SOAP::Extension/"SOAP11">

=back

=head2 SOAP12

Extends L<"SOAP12" in XML::Compile::SOAP::Extension|XML::Compile::SOAP::Extension/"SOAP12">.
 
=over 4

=item $obj-E<gt>B<soap12ClientWrapper>($operation, $call, $args)

Inherited, see L<XML::Compile::SOAP::Extension/"SOAP12">

=item $obj-E<gt>B<soap12HandlerWrapper>($operation, $callback, $args)

Inherited, see L<XML::Compile::SOAP::Extension/"SOAP12">

=item $obj-E<gt>B<soap12OperationInit>($operation, $args)

=item XML::Compile::Transport-E<gt>B<soap12OperationInit>($operation, $args)

Inherited, see L<XML::Compile::SOAP::Extension/"SOAP12">

=back

=head2 Accessors

=over 4

=item $obj-E<gt>B<address>()

Get a server address to contact. If multiple addresses were specified,
than one is chosen at random.

=item $obj-E<gt>B<addresses>()

Returns a list of all server contact addresses (URIs)

=item $obj-E<gt>B<charset>()

Returns the charset to be used when sending,

=back

=head2 Handlers

=over 4

=item $obj-E<gt>B<compileClient>(%options)

Compile a client handler.  Returned is a subroutine which is called
with a text represenation of the XML request, or an XML::LibXML tree.
In SCALAR context, an XML::LibXML parsed tree of the answer message
is returned.  In LIST context, that answer is followed by a HASH which
contains trace information.

 -Option    --Default
  hook        <undef>
  kind        'request-response'
  xml_format  0

=over 2

=item hook => CODE

See section L</Use of the transport hook>.
When defined, the hook will be called, in stead of transmitting the
message.  The hook will gets three parameters passed in: the textual
representation of the XML message to be transmitted, the trace HASH with
all values collected so far, and the transporter object.  The trace HASH
will have a massive amount of additional information added as well.

You may add information to the trace.  You have to return a textual
representation of the XML answer, or C<undef> to indicate that the
message was totally unacceptable.

=item kind => STRING

Kind of communication, as defined by WSDL.

=item xml_format => 0|1|2

[2.26] See XML::LibXML::Document subroutine toString.  With '1', you will get
beautified output.

=back

=back

=head1 DETAILS

=head2 Use of the transport hook

A I<transport hook> can be used to follow the process of creating a
message to its furthest extend: it will be called with the data as
used by the actual protocol, but will not connect to the internet.
Within the transport hook routine, you have to simulate the remote
server's activities.

There are two reasons to use a hook:

=over 4

=item .

You want to fake a server, to produce a test environment.

=item .

You may need to modify the request or answer messages outside the
reach of L<XML::Compile::SOAP|XML::Compile::SOAP>, because something is wrong in either
your WSDL of L<XML::Compile|XML::Compile> message processing.

=back

=head3 XML and Header Modifications

Some servers require special extensions, which do not follow any standard
(or logic). But even those features can be tricked, although it requires
quite some programming skills.

The C<transport_hook> routine is called with a C<$trace> hash, one of
whose entries is the UserAgent which was set up for the data transfer. You
can modify the outgoing message XML body and headers, carry out the data
exchange using the UserAgent, and then examine the returned Response for
content and headers using methods similar to the following:

 sub transport_hook($$$)
 {   my ($request, $trace, $transporter) = @_;
     my $content = $request->content;

     # ... modify content if you need
     my $new_content = encode "UTF-8", $anything;
     $request->content($new_content);
     $request->header(Content_Length => length $new_content);
     $request->header(Content_Type => 'text/plain; charset=UTF-8');

     # ... update the headers
     $request->header(Name => "value");

     # sent the request myself
     my $ua = $trace->{user_agent};
     my $response = $ua->request($request);

     # ... check the response headers
     my $name = $response->header('Name');

     # ... use the response content
     my $received = $response->decoded_content || $response->content;

     $response;
 }

You should be aware that if you change the size or length of the content
you MUST update the C<Content-Length> header value, as demonstrated above.

=head3 Transport hook for debugging

The transport hook is a perfect means for producing automated tests.  Also,
the XML::Compile::SOAP module tests use it extensively.  It works like this
(for the SOAPHTTP simluation):

 use Test::More;

 sub fake_server($$)
 {  my ($request, $trace) = @_;
    my $content = $request->decoded_content;
    is($content, <<__EXPECTED_CONTENT);
<SOAP-ENV:Envelope>...</SOAP-ENV:Envelope>
__EXPECTED_CONTENT

    HTTP::Response->new(200, 'Constant'
      , [ 'Content-Type' => 'text/xml' ]
      , <<__ANSWER
<SOAP-ENV:Envelope>...</SOAP-ENV:Envelope>
__ANSWER
 }
 
Then, the fake server is initiated in one of the follow ways:

  my $transport = XML::Compile::Transport::SOAPHTTP->new(...);
  my $http = $transport->compileClient(hook => \&fake_server, ...);
  $wsdl->compileClient('GetLastTracePrice', transporter => $http);

or

  my $soap = XML::Compile::SOAP11::Client->new(...);
  my $call = $soap->compileClient(encode => ..., decode => ...,
      transport_hook => \&fake_server);

or

  my $wsdl = XML::Compile::WSDL11->new(...);
  $wsdl->compileClient('GetLastTracePrice',
      transport_hook => \&fake_server);

=head3 Transport hook for basic authentication

[Adapted from an example contributed by Kieron Johnson]
This example shows a transport_hook for compileClient() to add to http
headers for the basic http authentication.  The parameter can also be
used for compileAll() and many other related functions.

  my $call = $wsdl->compileClient($operation
     , transport_hook => \&basic_auth );

  # HTTP basic authentication encodes the username and password with
  # Base64. The encoded source string has format: "username:password"
  # With the below HTTP header being required:
  #        "Authorization: Basic [encoded password]"

  use MIME::Base64 'encode_base64';

  my $user     = 'myuserid' ;
  my $password = 'mypassword';

  sub basic_auth($$)
  {   my ($request, $trace) = @_;

      # Encode userid and password
      my $authorization = 'Basic '. encode_base64 "$user:$password";

      # Modify http header to include basic authorisation
      $request->header(Authorization => $authorization );

      my $ua = $trace->{user_agent};
      $ua->request($request);
  }

=head1 Helpers

=over 4

=item XML::Compile::Transport-E<gt>B<register>($uri)

Declare an transporter type.

=back

=head1 SEE ALSO

This module is part of XML-Compile-SOAP distribution version 3.28,
built on August 01, 2022. Website: F<http://perl.overmeer.net/CPAN/>

=head1 LICENSE

Copyrights 2007-2022 by [Mark Overmeer <markov@cpan.org>]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://dev.perl.org/licenses/>