Re: [xmlblaster] Automatic Client failover

[Marcel Ruff <mr at marcelruff.info>]

David Robison wrote:
> What I want to do is to allow the client to detect when the node 
> supporting one of its subscriptions is down and to "move" its 
> subscription to another node. We have developed a plugin that allows a 
> node to send a periodic heart beat. If the client misses the heart 
> beat for a node on which it has subscribed for messages, it then will 
> be able to unsubscribe and then resubscribe, hopefully onto a node 
> that is up. What is missing in XMLBlaster is the ability to give 
> preference to nodes that are up and not just pick any node that 
> supports the data domain. This would need to be done (in my estimation 
> with the little bit I know of the code) in the ClusterManager and the 
> getConnection routine.
>
> Does this seem like a reasonable approach? Should it be possible to 
> make the change in getConnection to give preference to nodes that are 
> "up"? Could it be implemented as a special version of load balancing? 
> Any other ideas?
In ClusterManager.java:822

We have a masterSet of nodes which are available:
     NodeDomainInfo nodeDomainInfo = 
loadBalancer.getClusterNode(masterSet); // Invoke for 
masterSet.size()==1 as well, the balancer may choose to ignore it

and now the loadBalancer may choose the appropriate, which it does in 
the plugin RoundRobin.java
which chooses the node with the lowest stratum.
I think here is the place for any more advanced preference logic
or even another plugin,

regards
Marcel



> David Robison
> --
>
> David R Robison
> Open Roads Consulting, Inc.
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