NAME¶
SOAP::WSDL::Manual::Parser - How SOAP::WSDL parses XML messages
Which XML message does SOAP::WSDL parse ?¶
Naturally, there are two kinds of XML documents (or messages) SOAP::WSDL has to
parse:
- •
- WSDL definitions
- •
- SOAP messages
There are different parser implementations available for SOAP messages and WSDL
definitions.
WSDL definitions parser¶
SOAP::WSDL::Expat::WSDLParser¶
A parser for WSDL definitions based on XML::Parser::Expat.
my $parser = SOAP::WSDL::Expat::WSDLParser->new();
my $wsdl = $parser->parse_file( $filename );
The WSDL parser creates a tree of perl objects, whose root is a
SOAP::WSDL::Definitions element.
SOAP messages parser¶
SOAP::WSDL::Expat::MessageParser¶
SOAP::WSDL::Expat::MessageParser converts SOAP messages to SOAP::WSDL::XSD
object trees.
It uses a class resolvers for finding out which class a particular XML element
should be of, and type libs containing these classes.
Creating a class resolver
The easiest way for creating a class resolver is to run SOAP::WSDL's generator.
See wsdl2perl.
The class resolver must implement a class method "get_class", which is
passed a list ref of the current element's XPath (relative to Body), split by
/.
This method must return a class name appropriate for a XML element.
A class resolver package might look like this:
package ClassResolver;
my %class_list = (
'EnqueueMessage' => 'Typelib::TEnqueueMessage',
'EnqueueMessage/MMessage' => 'Typelib::TMessage',
'EnqueueMessage/MMessage/MRecipientURI' => 'SOAP::WSDL::XSD::Builtin::anyURI',
'EnqueueMessage/MMessage/MMessageContent' => 'SOAP::WSDL::XSD::Builtin::string',
);
sub new { return bless {}, 'ClassResolver' };
sub get_class {
my $name = join('/', @{ $_[1] });
return ($class_list{ $name }) ? $class_list{ $name }
: warn "no class found for $name";
};
1;
Skipping unwanted items
Sometimes there's unnecessary information transported in SOAP messages.
To skip XML nodes (including all child nodes), just edit the type map for the
message and set the type map entry to '__SKIP__'.
In the example above, EnqueueMessage/StuffIDontNeed and all child elements are
skipped.
my %class_list = (
'EnqueueMessage' => 'Typelib::TEnqueueMessage',
'EnqueueMessage/MMessage' => 'Typelib::TMessage',
'EnqueueMessage/MMessage/MRecipientURI' => 'SOAP::WSDL::XSD::Builtin::anyURI',
'EnqueueMessage/MMessage/MMessageContent' => 'SOAP::WSDL::XSD::Builtin::string',
'EnqueueMessage/StuffIDontNeed' => '__SKIP__',
'EnqueueMessage/StuffIDontNeed/Foo' => 'SOAP::WSDL::XSD::Builtin::string',
'EnqueueMessage/StuffIDontNeed/Bar' => 'SOAP::WSDL::XSD::Builtin::string',
);
Note that only SOAP::WSDL::Expat::MessageParser implements skipping elements at
the time of writing.
Creating type lib classes
Every element must have a correspondent one in the type library.
Builtin types should be resolved as SOAP::WSDL::XSD::Builtin::* classes
Creating a type lib is easy: Just run SOAP::WSDL's generator - it will create
both a typemap and the type lib classes for a WSDL file.
Sometimes it is nessecary to create type lib classes by hand - not all WSDL
definitions are complete.
For writing your own lib classes, see SOAP::WSDL::XSD::Typelib::Element,
SOAP::WSDL::XSD::Typelib::ComplexType and
SOAP::WSDL::XSD::Typelib::SimpleType.
SOAP::WSDL::Expat::Message2Hash¶
Transforms a SOAP message into a perl hash refs. Using this parser is usually
triggered by calling the "outputhash" method of SOAP::WSDL, or by
using SOAP::WSDL::Deserializer::Hash.
Acts somewhat like XML::Simple, but faster.
The following restrictions apply:
- •
- Ignores all namespaces
- •
- Ignores all attributes
- •
- Does not handle mixed content
- •
- The SOAP header is ignored
OLD SAX HANDLER¶
Historically, SOAP::WSDL used SAX for parsing XML. The SAX handlers were
implemented as XML::LibXML handlers, which also worked with
XML::SAX::ParserFactory.
Support for SAX and XML::LibXML in SOAP::WSDL is discontinued for the following
reasons:
- •
- Speed
XML::Parser::Expat is faster than XML::LibXML - at least when optimized for
speed.
High parsing speed is one of the key requirements for a SOAP toolkit - if
XML serializing and (more important) deserializing are not fast enough,
the whole toolkit is unusable.
- •
- Availability
XML::Parser is more popular than XML::LibXML.
- •
- Stability
XML::LibXML is based on the libxml2 library. Several versions of libxml2 are
known to have specific bugs. As a workaround, there are often several
versions of libxml2 installed on one system. This may lead to problems on
operating systems which cannot load more than one version of a shared
library simultaneously.
XML::LibXML is also still under development, while XML::Parser has had time
to stabilize.
- •
- SOAP::Lite uses XML::Parser
SOAP::Lite uses XML::Parser if available. SOAP::WSDL should not require
users to install both XML::Parser and XML::LibXML.
The old SAX handler historically used in SOAP::WSDL are not included in the
SOAP::WSDL package any more.
However, they may be obtained from the "attic" directory in
SOAP::WSDL's SVN repository at
https://soap-wsdl.svn.sourceforge.net/svnroot/soap-wsdl/SOAP-WSDL/trunk/attic
- •
- SOAP::WSDL::SAX::WSDLHandler
This is a SAX handler for parsing WSDL files into object trees SOAP::WSDL
works with.
It's built as a native handler for XML::LibXML, but will also work with
XML::SAX::ParserFactory.
To parse a WSDL file, use one of the following variants:
my $parser = XML::LibXML->new();
my $handler = SOAP::WSDL::SAX::WSDLHandler->new();
$parser->set_handler( $handler );
$parser->parse( $xml );
my $data = $handler->get_data();
my $handler = SOAP::WSDL::SAX::WSDLHandler->new({
base => 'XML::SAX::Base'
});
my $parser = XML::SAX::ParserFactor->parser(
Handler => $handler
);
$parser->parse( $xml );
my $data = $handler->get_data();
- •
- SOAP::WSDL::SAX::MessageHandler
This is a SAX handler for parsing WSDL files into object trees SOAP::WSDL
works with.
It's built as a native handler for XML::LibXML, but will also work with
XML::SAX::ParserFactory.
Can be used for parsing both streams (chunks) and documents.
LICENSE AND COPYRIGHT¶
Copyright 2007 Martin Kutter.
This file is part of SOAP-WSDL. You may distribute/modify it under the same
terms as perl itself.
AUTHOR¶
Martin Kutter <martin.kutter fen-net.de>
$Rev: 391 $
$LastChangedBy: kutterma $
$Id: Parser.pod 391 2007-11-17 21:56:13Z kutterma $
$HeadURL: https://soap-wsdl.svn.sourceforge.net/svnroot/soap-wsdl/SOAP-WSDL/trunk/lib/SOAP/WSDL/Manual/Parser.pod $