[Standards] Stanza Size Limits (was Re: [jdev] Communicate between two client instances of the same ID)

Artur Hefczyc artur.hefczyc at tigase.org
Wed Sep 3 17:07:09 UTC 2008

On 3 Sep 2008, at 15:13, Peter Saint-Andre wrote:

> Pedro Melo wrote:
>> On Sep 3, 2008, at 5:47 AM, Peter Saint-Andre wrote:
>>> Justin Karneges wrote:
>>>> Dragging this over from jdev:
>>>>>>> Hmm. XMPP is not optimized for sending around 100k+ messages.
>>>>>> Would 64KB chunks a reasonable thing to do?
>>>>> That's probably still too high.  There is currently no specified  
>>>>> maximum
>>>>> size for XMPP stanzas, but individual implementations may  
>>>>> enforce different
>>>>> values.  The original jabberd 1.0 server had around a 10KB  
>>>>> maximum.  The
>>>>> general consensus is that stanzas should be "small", and this is  
>>>>> largely in
>>>>> part because large stanzas block transmission of other stanzas  
>>>>> (you cannot
>>>>> send many stanzas in parallel over one stream).
>>>> Right now it's fuzzy as to how small you should chunk your data  
>>>> for maximum compatibility.  I think we should define the largest  
>>>> stanza size that must be supported by clients and servers.  We  
>>>> could just make this value 10000 bytes, from the opening '<' to  
>>>> the final '>' of the stanza.  The text should go into RFC 3920bis  
>>>> as a SHOULD.
>>>> This way, stanzas 10000 bytes or smaller are guaranteed to  
>>>> succeed in transmission.  Stanzas larger than 10000 bytes would  
>>>> still be transmittable, but without any guarantees that the other  
>>>> side will accept it (which is not any worse than the situation  
>>>> today).
>>>> A question: which stanza error are we supposed to use to reject a  
>>>> stanza that is too large?  Such an error would be very useful to  
>>>> determine the MTU.
>>> http://www.xmpp.org/extensions/inbox/stanzalimits.html
>> Why not make section 3 a stream feature instead?
>> Like:
>> <stream:features>
>>  <limits xmlns='urn:xmpp:tmp:stanza-limits'>
>>    <size>65355</size>
>>    <rate>10</rate>
>>  </limits>
>> </stream:features>
>> This would signal the client that the max stanza size is 65355  
>> bytes, and the max allowed rate of stanzas per second is 10.
> I like that.
> /psa


I like this too. The server can inform a client ahead of time what  
traffic limits are going to be enforced.

Artur Hefczyc

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