[ejabberd] Stanza size

Eric Cestari eric at ohmforce.com
Thu May 29 12:29:27 MSD 2008

Hi Peter,

> A few questions:
> - Why are you using XMPP to send such large stanzas? The technology is
> not optimized for such behavior.

Actually, the prototype I am working on has out-evolved the initial  
design I made. I actually did not expect such big stanzas to move  
around :)
> - Is the large data XML or binary?

binary, the body should not be parsed by the server. Just has to move  
it around.
> - Have you thought about sending the large data as a URL with a  
> pointer
> to files accessible via HTTP, or sending the large data outside the  
> band (e.g., via file transfer)?

Yes, I am considering to move those stanzas into a custom out of band  
protocol, and only use XMPP for advertising addresses, ports and keys.

> - Will your application run over the open Internet or federate with
> other XMPP services? If so, you will run into s2s limits.

It will not federate.

>> I have set the stanza size to an appropriate value, and on the test
>> server with only few connections it works ok.
>> However are there any side effects I should be aware of, regarding
>> ejabberd itself ?
> IMHO you might run into strange queueing behavior, especially if you  
> are
> sending to clients that don't have fat pipes -- as that 1Mb stanza is
> slowly pushed to the client, any other stanzas that you may want to  
> send
> to or from that client may be blocked (this is not an ejabberd- 
> specific
> problem and perhaps ejabberd handles that better than most XMPP  
> servers,
> I'm not sure).

I was expecting some side effects, indeed, thanks for pointing this  
one out.

The prototype was a prototype, that code will be thrown away... So  
I'll get that fixed with OOB data transfers (and that will simplify my  
code -- that's a good thing)

Thanks for your help.

Eric Cestari

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