On 11/10/09 8:00 PM, Jochen Bekmann wrote: > On Tue, Nov 3, 2009 at 7:59 AM, Peter Saint-Andre <[email protected]> wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> On 11/2/09 11:18 AM, Dan Peterson wrote: >> >>> * Reliable Delivery: >>> o For any communication mechanism it is important that there >>> is a contract for delivery of the message contents, and we >>> are working on a reliable delivery mechanism >>> from WaveSandbox.com. >> What is meant by "reliable delivery"? What are your requirements for a >> reliable delivery mechanism? I ask because the broader XMPP developer >> community has put a lot of thought into this problem, and depending on >> your needs a solution might already exist. Let's not reinvent the wheel >> if we don't need to. :) >> >> Peter > > Hi Peter, > > We're still working through some of the finer points on "reliable > delivery", we're also hoping to incorporate some form of flow control. > We have yet to write a full spec of how we envision this mechanism to > work, so if you allow be to be brief, we expect the requirements for > "reliable delivery" to be: > - short term retransmission and acknowledgement of all messages (this > can be done using regular XMPP mechanisms). > - selectively dropping non-essential messages queued for > retransmission if there are any non-trivial transmission delays (e.g. > delta updates, which can be recovered by a receiver using getHistory > on receipt of a commit notification). > - keeping retransmission efficient by only sending of essential > messages over a significant amount of time (e.g. days, weeks,.... > months? if a wave provider has gone offline. The retransmission policy > might be similar to what happens with SMTP (*)). Essential messages > would include the last commit notification for all wavelets on which a > provider has users. > > (*) One might possibly add an active mechanism on the receiver's part > to query for new waves, however there are a few issues with this. e.g > after being down for a long while, receivers can't know the complete > set of servers to contact for waves without some central authority > informing a provider which providers have waves for whom.
Thanks for sharing your thoughts on reliable delivery. Current XMPP servers typically don't do any kind of longer-term retransmission. Some of them handle short-term retransmission, and more will do so once they implement the Stream Management extension: http://xmpp.org/extensions/xep-0198.html Keep those requirements coming. :) -- Peter Saint-Andre https://stpeter.im/
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