[messaging] Minimal requirements for group chat

[Kurt Roeckx]

On Wed, Apr 16, 2014 at 08:59:22PM +0100, Michael Rogers wrote:
> > So the first question I really have, is this 1 master acceptable, 
> > or do you need a multi master solution?
> > 
> > If you go with 1 master, you can just have that one decide what the
> > order is, and hand out ids if needed.
> > 
> > If you're going for multi master, things might get more 
> > complicated, and I'm not sure it's needed.
> 
> Interesting idea... if we had a single master choosing the order,
> could we prevent the master from showing different orders to different
> members?

One way I think this can work is that the master is only
responsible for handing out ids.  That is, someone that wants to
send a message first asks the master and id.  Nobody else can get
an id until that message has been commited (or rolled back).

The ids should always be in sequence, no id can be skipped, and
the id would be part of the signed data in the message.

I think then you should have to make sure that all members confirm
that they saw the same message.


Kurt