[Standards] XEP-0047: IBB

Fabio Forno fabio.forno at gmail.com
Tue Feb 23 18:03:02 UTC 2010

Just got some doubts having several compatibility issues with block
sizes in different implementations  (lampiro, some bots, pidgin). All
the specs say about it is this sentence: "The data to be sent, prior
to any wrapping in the <data/> element and IQ or message stanza, MUST
NOT be larger than the 'block-size' determined in the bytestream

There is no indication whether:
- the size is the one of the original data or the b64 encode one (for
implementations it would easier if it were the non-encoded data)
- if each block must be a valid b64 block, i.e. with padding at the
end (again for implementation it be easier this solution, since we
don't have to buffer incoming stanzas)

On Sat, Feb 13, 2010 at 3:26 AM, Peter Saint-Andre <stpeter at stpeter.im> wrote:
> A few comments on XEP-0047...
> First, it might be useful if the error for "block size too big" provided
> more detailed information, because right now the recipient can't tell
> the sender what block size would be acceptable (e.g., if the sender
> proposes a block size of 4096 and the recipient returns an error, the
> initiator might then try a block size of 2048 but the receiver might
> still return an error; that seems to require too many round trips). I
> propose that we add an application-specific error condition that
> specifies the preferred block size:

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