Servlet chaining with active orchestration

[Stefán Baxter <st...@gm.is>]

Hi,

I'm pretty new to all of this so I'd like to apologize in advance if this is
already discussed in another context or by another name.

Within my development environment I tend to think of Servlets as the
preparation and content gathering tool that exists without a representation
layer. In this setup it's primary use is to contact EJBs, Databases, other
websites (XML or otherwise) etc. and prepare content from these sources for
use with a JSP.  After such a servlet has been called the request is
forwarded to a JSP  that has been defined statically or dynamically in
servlet it self.

This allows me to separate the, sometimes, complex programming tasks from
the relatively simple representation tasks. In other words, more experienced
programmers handle all functionality and HTML programmers handle the
representation.

This method has some great benefits for my and the company I work for. In
stead of a serial process when creating a web application:

Specification -> Design -> HTML -> Functionality & Representation
Programming

we get a more parallel path:

                 -> Servlet Programming
               /                        \
Specification -                          -> HTML & Representation
               \                        /
                 -> Design


This is all working very well, we have increased object reusability
amorously over our previous methods of embedding code into HTML with ASP,
EmbPerl etc. and utilized our resources better.

Now for the subject at hand; I would like, instead of calling a servlet
directly, to call a pipeline described by an XML file containing simple
logic and references to numerous Servlets called in a predefined or dynamic
sequence before calling a JSP. Parameters passed to the pipeline, servlet
responses or simple logic would control the path taken within an pipeline
and what JSP is called.