AxKit has a flexible tool called eXtensible Server Pages (XSP) for creating XML from various data sources such as relational databases, cookies, and form parameters. This technology was originally invented by the Apache Cocoon team, and AxKit shares their syntax. This allows easier migration of projects to and from Cocoon. (Cocoon allows you to embed Java code in your XSP, similar to how AxKit allows you to embed Perl code.)
XSP is an XML-based syntax that uses namespaces to provide extensibility. In many ways, this is like the Cold Fusion model of using tags to provide dynamic functionality. One of the advantages of using XSP is that it is impossible to generate invalid XML, which makes it ideal for use in an XML framework such as AxKit. Another is that the tags can hide complex functionality, allowing the XSP tags to be added by designers and freeing programmers to perform more complex and more cost-effective tasks.
The XSP framework allows you to design new tags, or use ones provided already by others on CPAN. These extra tags are called taglibs. By using taglibs instead of embedding Perl code in your XSP page, you can further build on AxKit's separation of content from presentation by separating out logic too. And creating new taglibs is almost trivial using AxKit's TagLibHelper module, which hides all the details for you.
In the examples below, we are going to show some code that embeds Perl code in the XSP pages. This is not a recommended practice, due to the ease with which you can extract functionality into tag libraries. However, it is more obvious to Perl programmers what is going on this way and provides a good introduction to the technology.