[messaging] Message order in group chat (attempt at summary)

[Trevor Perrin]

On Sat, Apr 19, 2014 at 5:27 PM, Tom Ritter <tom at ritter.vg> wrote:
> I think that heartbeats are going to be important. With the partial
> ordering UI I outlined, it's possible to reflow the conversation N
> seconds into the past, where N is whatever window is deemed
> acceptable. The way I expect it to work is that a user is not able to
> send a message that reflows the conversation too far in the past -
> that is, we just don't believe Bob if he claims he hasn't seen
> messages sent 5 seconds ago.

Good point that there should probably be "timeliness" checks based on
expected network delay:
 - new messages must be causal successors to any message received more
than X seconds ago
 - missing predecessors must arrive within X seconds

I think that has value even without requiring every party to transmit
something (hearbeat or regular message) every Y seconds.  Which might
be infeasible in some protocols (e.g. async messaging).


Trevor