xml-dev - RE: Changing the DTD declaration at runtime

["Steve Rowe" <sarowe@textwise.com>]

Why not set up another server (at the same machine on another port)
which is dedicated to serving the DTD?

> -----Original Message-----
> From: owner-xml-dev@xml.org
> [mailto:owner-xml-dev@xml.org]On Behalf Of
> Laura Neitzel
> Sent: Thursday, June 08, 2000 5:53 pm
> To: 'xerces-j-dev@xml.apache.org'; 'xml-dev@xml.org'
> Subject: Changing the DTD declaration at runtime
>
>
> Hi again!
>
> I am encountering a diagnosable problem with regards to the
> DTD declaration
> (<!DOCTYPE...>) in an Xml file.
>
> First, some background:
>
> Our system is set up such that we have a single "receiving"
> web/app server.
> This server processes all sorts of requests, one of which
> is xml. In other
> words, someone can send an xml doc to this web server (call it
> www.webserver.com for now) and we will process the document
> (add, update,
> delete from our db, etc) and return a response, via
> http--and a servlet
> (which we call XmlServlet). Our dtd may or may NOT be on
> this server;
> because the server is part of our product, customers may
> choose to put the
> dtd on a separate server.
>
> The problem:
> The problem is that of a deadlock when servicing too many requests.
> Basically, our webserver (Weblogic) has a configurable
> number of threads
> that it can handle at one time. This number is set to 15.
> If more than 15
> requests occur simultaneously (using LoadRunner here), a
> deadlock occurs.
> We believe this happens because each call to the XmlServlet
> spawns off a
> thread, and then each of these threads calls the web server again to
> retrieve the DTD (which is referenced as
> http://www.webserver.com/dtd/1.0/mydtd.dtd). Note that the
> DTD references 4
> .mod files.
> So, threads 1-15 are serviced via the servlet and weblogic
> then says "no
> more," but each of them needs to get the dtd to work with.
> Thread 1 asks the
> webserver for the dtd, but the webserver makes it wait
> until at least one of
> the 15 is finished... but none of them will ever finish,
> because they need
> the dtd to finish!!!
>
> The solutions:
> We think that one of the best ways to deal with this is to
> refer to the dtd
> directly through the filesystem
> (file:\d:\dtd\1.0\mydtd.dtd). However, for
> various reasons, we can't put the filesystem path in the
> xml document
> itself. We'd like to be able to translate
> http://www.webserver.com/dtd/1.0/mydtd.dtd to local path
> file:\d:\dtd\1.0\mydtd.dtd.
>
> Any suggestions for where to put the translation?
> We thought of altering the parser code-- where it reads in
> the dtd. Does
> anyone know where to do this?
> Another option would be to have someone else host the dtd.
> Is this commonly
> done?
>
> Thanks so very much,
> Laura
>
>
>
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