Re: [jgroups-users] total ordering protocols (sequencer)
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From: Bela B. <be...@ya...> - 2014-09-30 10:03:11
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Hi Andrey, I'd be interested in your paper once it is available. Yes, the range of seqnos requested from the coord by a member is something that's not yet implemented. I hope to find some time to do this in 4.0. Cheers, On 30/09/14 11:39, apalade wrote: >> Note that there is an experimental version of SEQUENCER2 [2], but it needs > some more work > > yes, this (i.e. SEQUENCER2) is based on a variant of the SEQUENCER protocol > which is already implemented in JGroups. The purpose of SEQUENCER2 is to > offload the coordinator. Both protocols are based on Fixed Sequencer class > (please see [1]). The difference between the two is who handles the > broadcast of the messages after allocation of the sequence numbers. In > SEQUENCER, the leader (i.e. coordinator) broadcasts the messages, wheres as > in SEQUENCER2 the node that initiates the message is in charge of > broadcasting the message to the rest of the nodes in the group. > > SEQUENCER implements the variant unicast-broadcast (see variant UB in [1], > section 4.1). SEQUENCER2 is based on the variant unicast-unicast-multicast > (see variant UUB in [1], section 4.1). In variant UUB, a request is made to > the coordinator for each message that the sending node wants to broadcast. > SEQUENCER2 improves the variant UUB by requesting from the coordinator a > range of sequence numbers for the messages accumulated in the sending node. > The coordinator replies with a range and the sending node is in charge of > allocating the numbers to each message in the queue and broadcast the > messages. Hence, only one request is made to the coordinator. > > I worked on a paper regarding this issue, but is not published yet. However, > initial tests show that SEQUENCER2 performs a bit better than SEQUENCER for > the proposed use case that the paper is based on. > > > [1]. Xavier Défago, André Schiper, and Péter Urbán. 2004. Total order > broadcast and multicast algorithms: Taxonomy and survey. ACM Comput. Surv. > 36, 4 (December 2004), 372-421. DOI=10.1145/1041680.1041682 > http://doi.acm.org/10.1145/1041680.1041682 > > > > -- > View this message in context: http://jgroups.1086181.n5.nabble.com/jgroups-users-total-ordering-protocols-sequencer-tp10345p10347.html > Sent from the JGroups - General mailing list archive at Nabble.com. -- Bela Ban, JGroups lead (http://www.jgroups.org) |