[Standards] Suggestions for updates to XEP-0071: XHTML-IM
Peter.Waher at clayster.com
Mon Nov 4 20:55:50 UTC 2013
I have some suggested additions to the XHTML-IM extension XEP-0071 (which is still in Draft). I would very much like to see these added to the existing document. I'll list them below with comments why I believe these are features that merit addition:
Tables are explicitly forbidden in the current version for the following reasons:
"... There is little or no foreseeable need for such elements within the context of instant messaging."
"The foregoing is doubly true of more advanced markup such as tables..."
This sounds like an unnecessary restriction probably stemming from the fact that "instant messaging" equates human-to-human chat applications to many people. However, XMPP is obviously much more than that.
There are many examples were the support for tables would actually be very beneficent, especially in human-to-machine chat applications, i.e. chatting with robots. (Machine-to-machine is obviously solved using XML and not text.) A robot often needs to return tabular information, for instance, voting results, to take an example that all XSF-members knows.
Another example can be the following. Using a simple chat client I connect to a device and read a sensor. Using only text, I'm forced to output the information using semi-tables using tab characters. Result:
Using tables in an XHTML-IM section, provides a better mechanism to output tabulated output. The Psi client supports this:
Support for a basic set of table support is thus warranted in IM-clients. The most basic would be support for <table>, <tr> and <td>, perhaps also with <th>. If colspan and rowspan attributes are seen as difficult to implement, they could be omitted. The important aspect here is to be able to output textual information in columns. The text-align attribute would be a bonus, but not required.
Data URI scheme
Rephrasing §7.5, regarding support of data URI scheme in IMG tags. It says its use is "not recommended". However, it could state that use by sender is not recommended for the reasons listed (i.e. possible large stanzas), but support for the URI scheme in the receiver should still be recommended (but not required), if somebody uses it anyway (i.e. it is not forbidden).
An important aspect of IMG tags is the ability to fetch images from anywhere reachable by an URL. However, publishing dynamic content in an XHTML layout might be difficult using HTTP-URLs, especially if the sender is not reachable from the client (i.e. lies behind a firewall). Optional methods for sending images over XMPP exist, but they cannot (?) be combined with XHTML and the IMG-tag.
However, the new extension HTTP over XMPP (XEP-0332) solves this by defining a new URI scheme: httpx. A reference to XEP-0332 would be in order from §7.5 (Image Module Profile) stating that images can be transferred using URLs if support for the httpx URI scheme is available by both sender and receiver.
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