Passing XML data between applications

John Martin John.Martin at
Thu Jul 1 20:02:31 BST 1999

I am trying to understand how applications can use XML to pass data to
one another.  Here is a scenario:  Say I have middleware that
applications must use to pass data back and forth.  The required data
structure if you're going to use the middleware is:


As the middleware, we don't care how the application structures the data
in the Application-Data tag.  It will most likely be different for each
application.  We're trying to write a DTD to describe this.  So, for
example, one application using the middleware, may have this description
of the Application-Data:


Another application using the middleware might describe their
Application-Data this way:

<Street-Address>95 Madison Ave</Street-Name>
<City>New York</City><State>New York</State><Zip>00921</Zip>

I'm trying to understand how you would describe this situation with a
DTD.  Would/can you have two DOCTYPE statements, such as:

<?xml version="1.0" encoding="ISO-8859-1"?>

Where the NCSB DTD is (basically):


and another APPL DTD which is (basically):


Or how does this work?  I am a very "concrete/practical" learner and
almost all the examples I see in these XML books are in the
"abstract/theoritica" realm.  And I can't even find an abstract
discussion of this particular kind of situation.  Being new to the
newsgroup and XML, I'd appreciate any pointers if anyone knows of a good
"practical" guide to XML development and/or if there is a better place
to ask these type of questions.


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