Update index.md | Fixing typo that reverses the meaning. #33625
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I think there is a typo here. It is the polite peer who will let go if its offer and become the callee instead of the caller.
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| @@ -296,7 +296,7 @@ Since rollback works by postponing changes until the next negotiation (which wil | |||
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| The code checks to see if the message is an offer, and if so, if the local signaling state isn't `stable`. If it's not stable, _and_ the local peer is the polite one, we need to trigger rollback so we can replace the outgoing offer with the new incoming one. And these must both be completed before we can proceed with handling the received offer. | |||
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| Since there isn't a single "roll back and use this offer instead", performing this change on the polite peer requires two steps, executed in the context of [`Promise.all()`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all), which is used to ensure that both statements execute completely before continuing to handle the received offer. The first statement triggers rollback and the second sets the remote description to the received one, thus completing the process of replacing the previously _sent_ offer with the newly _received_ offer. The impolite peer has now become the callee instead of the caller. | |||
| Since there isn't a single "roll back and use this offer instead", performing this change on the polite peer requires two steps, executed in the context of [`Promise.all()`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all), which is used to ensure that both statements execute completely before continuing to handle the received offer. The first statement triggers rollback and the second sets the remote description to the received one, thus completing the process of replacing the previously _sent_ offer with the newly _received_ offer. The polite peer has now become the callee instead of the caller. | |||
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Thanks @rajatsharma16 . I think you are right, but this is so confusing I am not certain.
Above it says:
An important thing to keep in mind is this: the roles of caller and callee can switch during perfect negotiation. If the polite peer is the caller and it sends an offer but there's a collision with the impolite peer, the polite peer drops its offer and instead replies to the offer it has received from the impolite peer. By doing so, the polite peer has switched from being the caller to the callee!
So
- if the caller was initially the polite peer, then yes, this is consistent. It isn't "stated" what happens if the impolite peer was the caller, or whether it was the caller in this case.
- This definition of caller/callee is confusing to me. In English I would assume the caller is the peer that initiated a call. The way this reads it is the peer that sends the offer that is accepted "becomes" the caller. If that is the definition the docs should say so much earlier.
- If that definition is correct then doesn't that mean the impolite server will always be the caller if there is a collision.
@wbamberg I'm not taking this over - really just wanted @rajatsharma16 to know we're not ignoring this. Do you have enough knowledge to answer this?
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Yes I think this is explained from the polite peer's perspective. If we look at the preceding line:
The first statement triggers rollback and the second sets the remote description to the received one, thus completing the process of replacing the previously sent offer with the newly received offer.
It is the polite peer that is having to do all this. The impolite one simply returns upon detecting a collision (It knows it will "win").
if (!polite) {
return;
}
Then the next line continues to talk about the polite peer:
The impolite peer has now become the callee instead of the caller.
This is where I feel the word impolite should be replaced by the word polite. Because the polite peer- which was the original caller [initiator] of the negotiation- has now become the callee, by discarding its offer and accepting the impolite peer's one.
Another way to say the same thing can be:
The impolite peer has now become the caller instead of the callee.
It just depends on whose perspective do we want to keep at the center while describing this.
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Coming to your points:
if the caller was initially the polite peer, then yes, this is consistent. It isn't "stated" what happens if the impolite peer was the caller, or whether it was the caller in this case.
The impolite peer returns upon detecting a collision. The code is common for both peers [this abstraction is the very essence of implementing the perfect negotiation pattern] .
This definition of caller/callee is confusing to me. In English I would assume the caller is the peer that initiated a call. The way this reads it is the peer that sends the offer that is accepted "becomes" the caller. If that is the definition the docs should say so much earlier.
For this discussion, we can assume that "caller" is the peer who sent out the offer first. Technically, at one point both peers have become "temporary callers" by sending out offers to each other (hence the collision). Once the deadlock resolves, one of them [in our case the polite one] will have thrown/ rollbacked its offer and instead prepared [and sent] answer for the incoming offer. We can say that if you answer you become the callee, which the polite peer has done in this case.
If that definition is correct then doesn't that mean the impolite server will always be the caller if there is a collision.
Yes it seems so. The impolite peer will "eventually" always become the caller.
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@wbamberg I'm not taking this over - really just wanted @rajatsharma16 to know we're not ignoring this. Do you have enough knowledge to answer this?
I'm not at all an expert on this but my reading is the same as both of yours. Thanks for the fix, @rajatsharma16 !
Description
I think there is a typo here. It is the polite peer who will let go if its offer and become the callee instead of the caller.
Motivation
To either help content become accurate or learn what I might be missing.
Additional details
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