[jboss-dev-forums] [Design of Clustering on JBoss (Clusters/JBoss)] - Re: JBAS-4919 - ha singletons in heterogenous topologies

Thu Apr 3 16:38:13 EDT 2008

Re: http://jira.jboss.com/jira/browse/JBAS-5155 

The other day was looking into the possibility of having this fixed in AS 4.x. There's 2 (well 4 really) ways this can be fixed:

1.- Add new API that allows either: a) passing the singleton name to the HASEP so that DRM can be queried, or b) passing a List to pickSingleton() with the ClusterNodes where the singleton is deployed.

2.- Use setManagedSingleton() as a way to pass the String version of the singleton name which is later used to query the DRM. It's got HACK written all over it, but we can do an instanceof for String within it in case someone out there calls this. One thing is for sure, a HASingleton can't be an instanceof String. This safes us the possibility of having to add new API in 4.x and all the trouble associated with it.

3.- Is it worth fixing this? Hmmmm, we haven't advertised this much which is good in some ways, but any day, someone running 4.x could come and report this to us in a support case.

4.- I guess we could take the add HA Singleton Election Policy functionality as experimental and hence not supported in 4.x. This could safe us a lot of headaches.

My preference right now is with either 2 or 4. Thoughts?

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