Questions about XML web publishing supported by Enhydra

Hi, every one,

I just get a task to construct an application to provide XML web publishing
functions under the framework of Enhydra. Since I never found anybody talked
about such a topic here, I want to get some advice from you.
 
The ideas are as following:
 
1, The main idea of this application is to publish the XML-based material to
internet. These material is generally document-based, in which different
presentation techniques could be embeded, i.e. MathML, SVG, FemML. So they
can be taken as the documents with the smallest session function.
 
2, These XML-based material will be organized in categories according to
their content. Users as different roles can access these material by
different set of operations, for instance, search, upload, delete, download
or browser these material online. Material can be uploaded from remote user,
so we suppport validity parsing for this. Besides, they can also be
downloaded in different formats, i.e. HTML, PDF, XML+XSLT. 
 
3, To support the access control, we keep the session information. Only the
people who login the system can access the material.
 
Here is my consideration:
1, To construct such an application, we considered to use Enhydra as the
application server. Servlet will be used to fulfill most of the functions. 
2, To support XML-documents online, Xalan is considered to be used for XSLT
stylesheet processors.
3, We need some tools to transform the material into different formats, for
example, PDF. Perhaps Apache FOP will be a good choice.
4, Some XML database could be used to store XML-based material, Apache
Xindice, for example.
5, Validating parser could be needed for document uploading. Is Xerces a
good choice?

So how about it? Would anybody give some advice for this, especially about
the Enhydra + Xalan? Has anyone the experience using Xalan in Enhydra?
Perhaps you would like to tell me the similar application somewhere. Thank
you very much for your any idea.

Sincerely yours
YYW