[Standards] Call for Experience: XEP-0229: Stream Compression with LZW

Sam Whited sam at samwhited.com
Thu Mar 22 11:45:50 UTC 2018

On Thu, Mar 22, 2018, at 02:58, Jonas Wielicki wrote:
> 1. What software has XEP-0229 implemented? Please note that the
> protocol must be implemented in at least two separate codebases (at
> least one of which must be free or open-source software) in order to
> advance from Draft to Final.

I have implemnted this in an open source project: https://godoc.org/mellium.im/xmpp/compress

> 2. Have developers experienced any problems with the protocol as
> defined in XEP-0229? If so, please describe the problems and, if
> possible, suggested solutions.

I am ignoring the security issues in 0138, but we probably want to figure out what to do with that and then do the same to this XEP.

Beyond that the protocol does not specify the width of literal codes which must be the same on the compression and decompression ends. I used a code width of 8 bits, which is probably a defacto standard since input must be the same width and we probably want to be able to compress full bytes. Still presumably another server could set a different bit width and then I would not be able to decompress their traffic.

I suggest fixing the width of literal codes to 8 bits. There's no reason we'd want to use anything else as far as I can tell.

> 3. Is the text of XEP-0229 clear and unambiguous? Are more examples
> needed? Is the conformance language (MAY/SHOULD/MUST) appropriate?
> Have developers found the text confusing at all? Please describe any
> suggestions you have for improving the text.

The text was clear (except for the omission I already mentioned).


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