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   Re: [xml-dev] Xqueeze: Compact XML Alternative

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On Tue, 04 Feb 2003 10:02:15 -0500
Mike Champion wrote:

> That said, the Xqueeze  approach of using a dictionary based on a pre- 
> arranged schema has been tried repeatedly, no? (e.g. WAP/WML?) Also, that 
> significantly tightens the coupling between the sender and receiver of the 
> XML.  Maybe that is acceptable at the application level, but that 
> middleware that is crunching thousands of XML messages/second isn't going 
> to want to know about every schema of every application that is throwing 
> data at it.

The middleware can generate the data-dictionary on it's own for any
specification (I've only implemented it for DTDs so far). The algorthm
is generic enough to enable unrelated software to generate exactly the
same dictionary for the same specification. I.e. the middleware can
take any specification from the user and use xqML to communicate with
any other xqML aware middleware.

For deployments where this is really going to matter, one application
would generally be using a limited number of document types. Take, for
example, an IM server (like Jabber) that uses XML-based messages. The
server will have to generate the dictionary only once for it's
protocol and a single memory representation of that dictionary would
be present as long as the server is running, irrespective of how much
traffic it is handling.

The server can choose to store a disk copy of that dictionary when it
shuts down. There is a format for file representation of the
dictionary too. The clients can do the same - they can load the
dictionary when they go up and unload it when they go down.

The dictionary itself can be shared with interacting applications in
three ways:
* All apps generate one for themselves locally
* A single app generates the dictionary and sends it to others
* Each document/stream may carry an internal dictionary

Tahir Hashmi (VSE, NCST)
tahir AT ncst DOT ernet DOT in

We, the rest of humanity, wish GNU luck and Godspeed


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