[Standards] Suggestions for updates to XEP-0071: XHTML-IM

Peter Waher Peter.Waher at clayster.com
Mon Nov 11 15:22:24 UTC 2013

Hello Matthew

Thanks for your response. My responses to your comments and questions follow:

>> I'm searching for the easiest way to make an extension enabling simple tables. My thought was that the simplest way (for IM client developers) was to perform add this extension through XHTML-IM. Perhaps that is not so?
>It probably is, from a protocol perspective. I don't know if it is, from an implementation perspective, very simple. It depends what clients are using to render XHTML-IM today, and whether they support tables.
>> Would you prefer an extension dedicated to sending tabular data only?
>That seems overkill to me in this case. Perhaps we could just push for
>(carefully) relaxing the restrictions in XEP-0071 that you feel prevents you from sending tables?

This would me my preferred choice also.

>The downside with this approach is that, although you could start sending tables today and be compliant, unless tables are documented somewhere then they won't ever be implemented in clients.

True. With permission I could help write such an extension for you all to revise. However, I would like to hear from Peter Saint-André also, as he's the original author of the extension, if he feels OK with this or prefers to do any additions himself.

>> If that is the general consensus, I can write and propose such an extension.
>Are there any other things you find lacking in XEP-0071? If so, perhaps some "Extended XHTML-IM" XEP would be in order?

My personal needs regarding XHTML-IM is the following:

1) Very basic table support. The need is really to be able to output tabulated text. Nothing more fancy than that. If there's an option to left, center or right align contents of cells (or columns), even better but I can live without it. My option is to send plain text messages using tab characters (\t). This works as long as text in cells are roughly the same width, but not for content with more varying widths.

2) Possibility to include dynamically generated images in output (from API calls not stored in files). Since <img> tags are supported in XHTML-IM, this can be done using one of two methods:

2a) Using the data URI scheme and embed the image in the HTML itself. XEP-0071 actually recommends against supporting the data URI scheme, but does not prohibit it. I would like to lift this non-recommendation, but keep a recommendation on size of message stanza. In an earlier mail I also write that it could be good to differentiate between what is recommended by the sender and what is recommended by the received. It could be recommended by the received (chat clients) to support this to some extent, but not recommended by senders, since full support for it may not be guaranteed.

2b) Mentioning the httpx URI scheme (XEP-0332) in the same section. If supported (by the src attribute in img tags), this would also solve the issue.

Of the two needs, table support is clearly the most important.

Best regards,
Peter Waher

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