Hi Sam, On Freitag, 16. Juli 2021 13:45:27 CEST Sam Whited wrote: > There has been a lot of discussion about bind2 as a potential way to fix > the Message Carbons race condition
> (quick summary: when the connection > starts you go to enable carbons with the IQ, but you've already received > a few messages that aren't carbon copied before the IQ gets sent). I do not think that that is the race condition people generally worry about. The race condition people generally worry about is between MAM and Carbons, not between resource binding/the first messages and carbons. Even though there might be some slight awkwardness if you receive messages before enabling carbons, that would be irrelevant if there was a proper sync point with MAM. > However, bind2 is still in an early unfinished state and even once it's > done isn't likely to achieve adoption immediately because it's a bigger > XEP than just the single feature that it enables carbons and it does a > lot more that people will hae to think about, making its adoption slower > (though hopefully still relatively fast). > > In the mean time I'd like to suggest that carbons just add a simple > stream feature and call it a day so that we can stop dealing with the > race condition. > > I've proposed some text here: > > https://github.com/xsf/xeps/pull/1090 Now even if the above race condition was the one I was concerned about, I don't see how the text as written in your PR fixes anything. How is a nonza different from an IQ, if both happen post-resource-binding, as I understand from your text? I'd argue that the nonza is even worse because you cannot know when (with respect to the incoming stream of messages) carbons has been enabled (as there is no reply). If the nonza (from the stream feature) were allowed to be sent *before* resource binding, then there would be an interesting case where you could announce to the server that you want carbons before the first message is delivered. It doesn't fix the issue with MAM, but at least you know that from the point on your resource was bound, you got a complete picture of all (carbons-eligible) messages received on the account, which is somewhat nice. Though I should mention that you could also simply ignore all incoming messages until you get a reply to your carbons IQ and you had approximately the same sync point (due to the in-order requirement of stanza processing in XMPP). kind regards, Jonas
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