CGI::XMLApplication 1.1.3 review

CGI::XMLApplication is an Object Oriented Interface for CGI Script Applications. SYNOPSIS use CGI::XMLApplication; $scri

License: Perl Artistic License File size: 21K Developer: Christian Glahn

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CGI::XMLApplication is an Object Oriented Interface for CGI Script Applications.

SYNOPSIS

use CGI::XMLApplication;

$script = new CGI::XMLApplication;
$script->setStylesheetPath( "the/path/to/the/stylesheets" );

# either this for simple scripts
$script->run();
# or if you need more control ...
$script->run(%context_hash); # or a context object

CGI::XMLApplication is a CGI application class, that intends to enable perl artists to implement CGIs that make use of XML/XSLT functionality, without taking too much care about specialized errorchecking or even care too much about XML itself. It provides the power of the XML::LibXML/ XML::LibXSLT module package for content deliverment.

As well CGI::XMLApplication is designed to support project management on code level. The class allows to split web applications into several simple parts. Through this most of the code stays simple and easy to maintain. Throughout the whole runtime of a script CGI::XMLApplication tries to keep the application stable. As well a programmer has not to bother about some of XML::LibXML/ XML::LibXSLT transformation pitfalls.

The class module extends the CGI class. While all functionality of the original CGI package is still available, it should be not such a big problem, to port existing scripts to CGI::XMLApplication, although most functions used here are the access function for client data such as param().

CGI::XMLApplication, intended to be an application class should make writing of XML enabled CGI scripts more easy. Especially because of the use of object orientated concepts, this class enables much more transparent implemententations with complex functionality compared to what is possible with standard CGI-scripts.

The main difference with common perl CGI implementation is the fact, that the client-output is not done from perl functions, but generated by an internally build XML DOM that gets processed with an XSLT stylesheet. This fact helps to remove a lot of the HTML related functions from the core code, so a script may be much easier to read, since only application relevant code is visible, while layout related information is left out (commonly in an XSLT file).
This helps to write and test a complete application faster and less layout related. The design can be appended and customized later without effecting the application code anymore.

Since the class uses the OO paradigma, it does not force anybody to implement a real life application with the complete overhead of more or less redundant code. Since most CGI-scripts are waiting for events, which is usually the code abstraction of a click of a submit button or an image, CGI::XMLApplication implements a simple event system, that allows to keep event related code as separated as possible.

Therefore final application class is not ment to have a constructor anymore. All functionality should be encapsulated into implicit or explicit event handlers. Because of a lack in Perl's OO implementation the call of a superclass constructor before the current constructor call is not default behavior in Perl. For that reason I decided to have special events to enable the application to initialize correctly, excluding the danger of leaving important variables undefined. Also this forces the programmer to implement scripts more problem orientated, rather than class or content focused.

Another design aspect for CGI::XMLApplication is the strict differentiation between CODE and PRESENTATION. IMHO this, in fact being one of the major problems in traditional CGI programming. To implement this, the XML::LibXML and XML::LibXSLT modules are used by default but may be replaced easily by any other XML/XSLT capable modules. Each CGI Script should generate an XML-DOM, that can be processed with a given stylesheet.

Requirements:
Perl