Brian Candler wrote: > On Mon, Apr 19, 2010 at 11:01:24AM +0200, Martin Sustrik wrote: >> Yes. This can be achieved in two ways: >> >> 1. On top of 0MQ. Each client simply chooses a random server to connect to. > > But I didn't think the 0MQ API provided a way for the application to detect > whether its chosen endpoint is reachable or not, and hence move to a > different server. Or have I missed something?
No. There would be no failover in this case. The server would have to come back online to process the request. >> 2. Using a shared queue. All clients connect to the queue. All >> servers connect to the queue. Queue manages fair load-balancing of >> client requests among the servers. > > Sure - or a TCP load-balancer, if your server nodes are located near to each > other. > > Having clients be able to failover to a secondary data centre, or load > balance across two data centres, is still desirable. Note that 0MQ is designed in such a way as to allow for N-hop message routes. In this particular context it can mean, for instance, that client can load-balance (and failover) between two datacenters, while the queue within each datacenter can load-balance (and failover) between service instances in the datacenter. Martin _______________________________________________ zeromq-dev mailing list zeromq-dev@lists.zeromq.org http://lists.zeromq.org/mailman/listinfo/zeromq-dev
