2008/3/5 Peter Saint-Andre <[EMAIL PROTECTED]>: > > Maybe not, SXE would work as a binary protocol just as well but > > "object synchronization" does seems like a useful general purpose task > > worth standardizing... > > So the question is: does SXE basically do what we need for minimal > object syncronization and then people can build various applications on > top of that? Fabio seems to think that it doesn't quite meet his needs > (it does too much or not enough) but I'm not sure why...
Sorry, too much trashing in the last days, lowering my attention to the topic. There are two types of possible synchronizations: - The whiteboarding (stream) style, where each entity does small changes, modifying attributes or adding few nodes to the DOM. For this SXE is super and it seems really easy to use, sorry if there's been the impression I'm not fine with it. There are only two possible "improvements" (I'm even not saying issues): find a way for the initial synchronization, when the joining entity must get the whole document, and a control protocol for the event stream. As you say it's a problem to send the whole document in a message if it's huge, but if it's huge it may be a problem to retrieve it with thousands of messages defining the structure as well. In the xiclets stuff we are starting thinking to get our documents using http of ibb (and we have the usual file transfer problem... but i think that ibb can be nicer that SXE for the initial flood; we need figures, but I've the strong feel this is true, I could even bet few bucks :P). Therefore I think that in SXE it should be useful to have a pluggable initial state configuration, in which you can offer the most appropriate methods, then after that you can go on with SXE happily. The control stuff instead is something at a different level: I just think that as with RTP we define also a RTCP control channel, the same should be useful for SXE. Also in 1-1 there few meta events that are general and that we should carry (e.g locking, errors, requests of resynchronization from a particular point, perhaps also timing for applying changes). However this is a different XEP and it should be possible to make it work with SXE just using jingle in the correct way. - the object synchronization style: as we have seen at the DevCon it's a completely different scenario, and especially after these mails I came to the conclusion that SXE will never be used for this, unless making it too much complicated. In applications such as in xiclets is the application logic that must manage node ids (and only some node ids may be useful), adding an external layer of node ids as in SXE is heavy and of little usefulness. Moreover when reacting to user events most of DOM changes are applied in two ways for which SXE is either too heavy or rigid: the app may load & replace whole new chunks or screen or it may modify the structure just locally (with the js code) and send to other peer just UI events (e.g. button pressed) or data (e.g send a form). Finally, to draw a conclusion: I stop thinking of SXE for other applications than the whiteboarding style. I hope to have decreased the level of confusion with this mail, if not I'll try again ;) -- Fabio Forno, Ph.D. Bluendo srl http://www.bluendo.com jabber id: [EMAIL PROTECTED]
