Pod::WSDL - Creates WSDL documents from (extended) pod
use Pod::WSDL; my $pod = new Pod::WSDL(source => 'My::Server', location => 'http://localhost/My/Server', pretty => 1, withDocumentation => 1); print $pod->WSDL;
How does Pod::WSDL work? If you instantiate a Pod::WSDL object with the name of the module (or the path of the file, or an open filehandle) providing the web service like this
my $pwsdl = new Pod::WSDL(source => 'My::Module', location => 'http://my.services.location/on/the/web');
Pod::WSDL will try to find My::Module in @INC, open the file, parse it for WSDL directives and prepare the information for WSDL output. By calling
My::Module
@INC
$pwsdl->WSDL;
Pod::WSDL will output the WSDL document. That's it.
When using Pod::WSDL, the parser expects you to do the following:
Put the pod directly above the subroutines which the web service's client is going to call. There may be whitespace between the pod and the sub declaration but nothing else.
Use the =begin/=end respectively the =for directives according to standard pod: anything between =begin WSDL and =end will be treated as pod. Anything composing a paragraph together with =for WSDL will be treated as pod.
=begin
=end
=for
=begin WSDL
=for WSDL
Any subroutine not preceeded by WSDL pod will be left unmentioned. Any standard pod will be ignored (though, for an exception to this, see the section on own complex types below).
The individual instructions for Pod::WSDL always begin with a keyword, like _RETURN or _DOC or _FAULT. After this different things may follow, according to the specific type of instruction. The instruction may take one or more lines - everything up to the next line beginning with a keyword or the end of the pod is belonging to the current instruction.
_RETURN
_DOC
_FAULT
How do we use Pod::WSDL? In describing a web service's method we have to say something about parameters, return values and faults. In addition you might want to add some documentation to these items and to the method itself.
WSDL differentiates between in-, out- and inout-parameters, so we do that, too. A different matter is the question, if the client can do this too, but now we are talking about possibilities, not actualities.
The pod string describing a parameter has the structure
(_IN|_OUT|_INOUT) NAME ($|@)TYPE DESCRIPTION
like
_IN foo $string This is a foo
or
_INOUT bar @bar An array of bars
You will easily guess what _IN, _OUT and _INOUT stand for so we can move on. NAME is the name of your parameter. It does not have any real function (the order of the parameters being the only important thing) but it is nice to have it since in a WSDL document the parameters need to have names. So instead of having Pod::WSDL automatically generate cryptic names (it cannot do that right now) be nice to the client and use some sensible name. The TYPE of the parameters can be any of the xsd (schema) standard types (see [5]) or a type of your own creation. The $ resp. @ symbols tell Pod::WSDL and your client if it is a scalar or array parameter. Everything following the type up to the next instruction is treated as the parameter's documentation. If you call the constructor of Pod::WSDL with the argument withDocumentation => 1, it will be added to the WSDL.
_IN
_OUT
_INOUT
NAME
TYPE
$
@
withDocumentation => 1
Return values work like parameters but since in WSDL there is provision for only one return value (you have (in)out parameters, or can return arrays if that isn't enough), you do not need to give them a name. Pod::WSDL will automatically call them 'Return' in the WSDL document. So, the structure of _RETURN instructions is
_RETURN ($|@)TYPE DESCRIPTION
as in
_RETURN $string Returns a string
The pod for one method may only have one _RETURN instruction. If you don't specify a _RETURN instruction, Pod::WSDL will assume that you return void. Of course the perl subroutine still will return something, but your web service won't. To make this clear Pod::WSDL generates an empty response message for this.
If you want some method to be a one way operation (see [4], ch. 2.4.1), say so by using the instruction _ONEWAY in the pod. In this case no response message will be generated and a _RETURN instruction will be ignored.
_ONEWAY
SOAP faults are usually translated into exceptions in languages like Java. If you set up a web service using SOAP::Lite, SOAP will trap your dying program and generate a generic fault using the message of die. It is also possible to access SOAP::Lite's SOAP::Fault directly if you want more control - but this is not our issue. If you want to use custom-made fault messages of your own, define them in _FAULT instructions, which look like this:
die
_FAULT TYPE DESCRIPTION
An example could be the following:
_FAULT My::Fault If anything goes wrong
Since you probably won't return an array of fault objects, you do not need to use the ($|@) tokens. Just say that you return a fault, declare its type and add an optional description.
($|@)
As with parameters (but in contrary to _RETURN instructions) you can declare as many _FAULT instructions as you like, providing for different exception types your method might throw.
Method documentation is easily explained. Its structure is
_DOC Here comes my documentation ...
That's it. Use several lines of documentation if you like. If you instantiate the Pod::WSDL object with the parameter withDocumentation => 1, it will be written into the WSDL document.
Quite often it will be the case that you have to use complex types as parameters or return values. One example of this we saw when talking about faults: you might want to create custom fault types (exceptions) of your own to fullfill special needs in the communication between web service and client. But of course you also might simply want to pass a complex parameter like a address object containing customer data to your application. WSDL provides the means to describe complex types borrowing the xsd schema syntax. Pod::WSDL makes use of this by allowing you to add WSDL pod to your own types. Assuming you have some own type like
package My::Type; sub new { bless { foo => 'foo', bar => -1 }, $_[0]; } 1;
simply describe the keys of your blessed hash like this.
=begin WSDL _ATTR foo $string A foo _ATTR bar $integer And a bar =end WSDL
Put this pod anywhere within the package My::Type. Pod::WSDL will find it (if it is in @INC), parse it and integrate it into the WSDL document. The _ATTR instruction works exactly as the _IN, _OUT and _INOUT instructions for methods (see above).
_ATTR
If you initialize the Pod::WSDL object using withDocumentation => 1, Pod::WSDL will look for standard pod in the module, parse it using Pod::Text and put it into the WSDL document.
Instantiates a new Pod::WSDL.
source - Name of the source file, package of the source module or file handle on source file for which the WSDL shall be generated. This source must contain specialized Pod tags. So, if your source is '/some/directory/modules/Foo/Bar.pm' with package declaration 'Foo::Bar', source may be '/some/directory/modules/Foo/Bar.pm' or 'Foo::Bar' (in which case '/some/directory/modules' has to be in @INC) or an open file handle on the file. Right?
location - Target namespace for the WSDL, usually the full URL of your webservice's proxy.
pretty - Pretty print WSDL, if true. Otherwise the WSDL will come out in one line. The software generating the client stubs might not mind, but a person reading the WSDL will!
withDocumentation - If true, put available documentation in the WSDL (see "Pod Syntax" above). For used own complex types ('modules') this will be the output of Pod::Text on these modules. The software generating the client stubs might give a damn, but a person reading the WSDL won't!
Returns WSDL as string.
Adds a namespace. Will be taken up in WSDL's definitions element.
URI of the namespace
Declarator of the namespace
Carp XML::Writer IO::Scalar Pod::Text
The test scripts use
XML::XPath
see the *.t files in the distribution
Please send me any bug reports, I will fix them or mention the bugs here :-)
Of course, one subroutine declaration might take a lot of different sets of parameters. In Java or C++ you would have to have several methods with different signatures. In perl you fix this within the method. So why not put several WSDL pod blocks above the method so the web service's client can handle that.
Right know, the pod is found using some rather complex regular expressions. This is evil and will certainly fail in some situations. So, an issue on top of the fixme list is to switch to regular parsing. I'm not sure if I can use Pod::Parser since I need the sub declaration outside the pod, too.
So far, Pod::WSDL assumes a one to one relation between packages and files. If it meets several package declarations in one file, it will fail some way or the other. For most uses, one package in one file will presumably suffice, but it would be nice to be able to handle the other cases, too.
Array based blessed references used for complex types are something of a problem.
If you use complex types for parameters that are not your own (we assume, that the module containing the web service always is your own), you might not be able to put the WSDL pod into the module files. So why not fetch it from somewhere else like a configuration file?
With Axis, you simply call the web service's URL with the parameter '?wsdl' and you get the WSDL document. It would be nice to be able to do this with SOAP::Lite, too.
Pod::WSDL writes WSDL documents in encoded RPC style. It should be able to generate literal RPC and document styles, too.
[1] http://ws.apache.org/axis/
[2] http://search.cpan.org/~kbrown/SOAP-0.28/
[3] http://search.cpan.org/~byrne/SOAP-Lite-0.65_5/
[4] http://www.w3.org/TR/wsdl.html
[5] http://www.w3.org/TR/xmlschema-2/
http://ws.apache.org/axis/ http://search.cpan.org/~kbrown/SOAP-0.28/ http://search.cpan.org/~byrne/SOAP-Lite-0.65_5/ http://www.w3.org/TR/wsdl WSDL::Generator (a different way to do it) SOAP::WSDL (the client side) SOAP::Clean::WSDL (I have not tried this)
Tarek Ahmed, <bloerch -the character every email address contains- oelbsk.org>
Copyright (C) 2006 by Tarek Ahmed
This library is alpha software and comes with no warranty whatsoever. It is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.5 or, at your option, any later version of Perl 5 you may have available.
To install Pod::WSDL, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Pod::WSDL
CPAN shell
perl -MCPAN -e shell install Pod::WSDL
For more information on module installation, please visit the detailed CPAN module installation guide.