[Standards] XEP-0147: "?subscribe" or "?roster"

Kim Alvefur zash at zash.se
Tue Jun 7 14:29:44 UTC 2016

On 2016-06-07 06:11, Georg Lukas wrote:
> Hi,
> I want to expose an xmpp: URI of the user's account in my client to
> allow easy "contact sharing" to other IM users. Fortunately, XMPP is
> ultra flexible, allowing for any reasonable or potential usage form due
> to its separation between "roster" and "presence subscription".
> Now, as an IM application developer I need to decice whether I should
> expose the query-less URI <xmpp:romeo at example.net> or one with an action:
> <xmpp:romeo at example.net?subscribe> or <xmpp:romeo at example.net?roster>.
> For the query-less URI there seems to be no actual definition (neither
> RFC 5122 nor XEP-0147 nor registrar/querytypes.xml handle this case).
> The "?roster" action is defined by XEP-0147 and allows specifying the
> item name and group for the new item, however it does not mandate
> actually issuing a subscription request.
> The "?subscribe" action does almost the opposite: it performs roster
> addition and issues a subscription request, but it does not allow
> setting the name or group.

Both of these seem to be low-level protocol things, is that what we need?

> This leads to multiple questions:
> 1. Should we specify a more-or-less sane default action for query-less
> URIs?

Is 'chat' not the default?  Is that not sane?  If not, why not?  You
could make it easy to add someone if the URI is not in their roster.

> 2. Which one of the above forms should I use, ideally?
> 3. Which one of the above forms ensures the widest compatibility with
> existing clients? (Compliance suite, anyone?)
> 4. Should we define yet another action type "?rostersubscribe" that
> combines the name/group parameters of the former with the subscription
> request of the latter?

Maybe something less specific, more abstract, like ?add, where the
client is expected to do something sensible?

> 5.  Or maybe just add the "name" and "group" parameters to "?subscribe",
> as unknown parameters must be ignored by legacy clients anyway?

Otherwise this sounds pretty sensible.

Kim "Zash" Alvefur

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