[Spread-users] Spread vs ACE for publish/subscribe

Yair Amir yairamir at cnds.jhu.edu
Mon Nov 24 09:29:12 EST 2003


Doing a round robin with Spread is not that hard without developing
software: Have your servers join one group and keep track of their
index in the group by looking at the membership message
(the membership message is identically delivered
to all of the members of a group).

Then, have the clients send requests to that group using Agreed order.

Now, say we currently have n servers in the group.
Count the requests that are received after a server group membership event.
Each server should just serve requests that meet this condition:
server_index_in_membership == req_index mod n.

This will give the round robin effect without writing software.


       :) Yair.

James> No ACE doesn't provide group communication semantics, and you are right, it does
James> seem to have an infinite number of wrappers/facades. The issue is that neither
James> provides publish/subscribe with both broadcast and round-robin. Therefore, we'd
James> have to do some work ourselves, regardless of which package we choose.

James> It appears that we'd have to write our own server, using ACE. With Spread I
James> believe we'd either have to write our own server just for the round-robin
James> functionality (and use it as is for broadcast), or we'd have to put more
James> functionality into the clients so that they'd implment the round-robin on their
James> own (via private group names and unicast).

James> Given neither solution directly meets our needs, I was querying the list to see
James> if anyone had tried something similar and choosen one package over the other,
James> run into issues one package wouldn't solve, etc. I know... a pretty open
James> question, but I figured it wouldn't hurt to ask. :-)

James>         James.

>> -taj
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