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+Time to solve the assistant's [[cloud]] notification problem. This is
+really the last big road-bump to making it be able to sync computers
+across the big, bad internet.
+
+So, IRC still seems a possibility, but I'm going to try XMPP first. Since
+Google Talk uses XMPP, it should be easy for users to get an account, and
+it's also easy to run your own XMPP server.
+
+Played around with the Haskell XMPP library. Clint helpfully showed me an
+example of a simple client, which helped cut through that library's thicket
+of data types. In short order I had some clients that were able to see each
+other connecting to my personal XMPP server. On to some design..
+
+1. I want to avoid user-visible messages.
+   (dvcs-autosync also uses XMPP, but I checked the code and it
+   seems to send user-visible messages, so I diverge from its lead here.)
+   This seems very possible, only a matter of finding the right
+   way to use the protocol, or an appropriate and widely deployed extension.
+   The only message I need to send with XMPP, really, is "I have pushed to our
+   git repo". One bit of data would do; being able to send a UUID of the repo
+   that did the update would be nice.
+
+2. I'd also like to broadcast my notification to a user's buddies.
+   dvcs-autosync sends only self-messages, but that requires every node
+   have the same XMPP account configured. While I want to be able to run
+   in that mode, I also want to support pairs of users who have their own XMPP
+   accounts, that are buddied up in XMPP.
+
+3. To add to the fun, the assistant's use of XMPP should not make that XMPP
+   account appear active to its buddies. Users should not need a dedicated
+   XMPP account for git-annex, and always seeming to be available when
+   git-annex is running would not be nice.
+
+The first method I'm trying out is to encode the notification
+data inside a XMPP presence broadcast. This should meet all three
+requirements. The plan is two send two
+presence messages, the first marks the client as available, and the second
+as unavailable again.
+The "id" attribute will be set to some
+value generated by the assistant. That attribute is allowed on presence
+messages, and servers are [required to preserve it](http://xmpp.org/rfcs/rfc6121.html#presence-probe-inbound-id)
+while the client is connected.
+(I'd only send unavailable messages, but while
+that worked when I tested it using the prosody server, with google talk,
+repeated unavailable messages were suppressed. Also, google talk does not
+preserve the "id" attribute of unavailable presence messages.)
+
+If this presence hackery doesn't work out, I could try
+[XEP-0163: Personal Eventing Protocol](http://xmpp.org/extensions/xep-0163.html).
+But I like not relying on any extensions.