[Sugar-devel] Service announcement scheme - (Re: A small request.)

[C. Scott Ananian]

On Mon, Feb 2, 2009 at 8:58 AM, Bernie Innocenti <bernie at laptop.org> wrote:
> Morgan Collett wrote:
>> Also don't blame avahi for the fact that we send out updates every
>> time you alt-tab between shared activities, so that your icon can jump
>> to the appropriate snowflake on everyone else's Neighborhood Views...
>> as well as sending who joined and left...
>
> Mature GUIs have a common pattern to avoid too much graphical
> flickering on possibly rapid state transitions, such as setting a busy
> pointer or disabling buttons while some operation is in progress.
>
> I don't know if it has a name, but the algorithm is exactly the same
> for de-bouncing mechanical keys: you propagate the event only after
> the state has settled for a certain amount of time.
>
> This would take away a certain percentage of spurious updates, but the
> number basically remains proportional to the number of users so it
> doesn't scale much better.

http://wiki.laptop.org/go/Network_architecture#Direct_presence_interrogation
describes an algorithm to ensure that the amount of traffic in the net
is kept proportional to the number of users.  (The algorithm you
describe is actually proportional to the number of users squared or
cubed, because the size of the messages as well as the number of such
messages increases with the # of users.  If a mesh network is
involved, the number of rebroadcasts necessary is another factor
roughly proportional to the size of the network.)
 --scott

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