[JDEV] Re: Binary XML useful for Jabber?

[Jens Alfke]

On Tuesday, May 22, 2001, at 08:34 AM, David_Lucek at 3com.com wrote:

> From reading the documents, it looks like Jabber just sends ASCII XML 
> over
> the wire, correct?

Correct.

> Have any of the architects/developers considered using
> binary XML as defined in the Wireless Access Protocol(WAP) 
> specification?   It
> would save transmission bandwidth but are there other disadvantages to 
> using it?

It's been a while since I read the binary XML spec, but from what I 
recall, there is a header at the beginning that establishes a dictionary 
for tokenizing the XML element and attribute names used in the file. If 
that's true and it's required that all names appear in this dictionary, 
then the protocol wouldn't work for an open-ended stream as used by 
Jabber, since you couldn't know when the stream was opened what keywords 
might be used in it later on.

Otherwise this might be very interesting to look into. It should be a 
lot simpler to parse than regular XML, and will send fewer bytes over 
the wire, both of which would be good for small wireless clients like 
phones and PDAs (after all, that's why the WAP people invented it.)

Incidentally I've heard both of these issues (primarily the parsing 
overhead) mentioned as problems with Jabber -- "oh, won't Jabber be 
really slow since you have to parse all that XML?"

Could you post a URL for the binary XML spec so we can [re]read it?

BTW, I suggest we continue this thread on the protocol list instead of 
jdev. (I've set the reply-to header accordingly.)

—Jens
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