[jboss-dev-forums] [Design of POJO Server] - Issues with EJB2 ClusterConfigMetaData

[bstansberry@jboss.com]

Been chasing down EJB2 clustering testsuite failures, which got me looking into handling of org.jboss.metadata.ejb.jboss.ClusterConfigMetaData. Found a few things:

1) Class exposes properties home(bean)LoadBalancingPolicy.  DTD says they should be home(bean)LoadBalancePolicy (Balance not Balancing).  

That's a simple fix I've already made in my workspace; please advise if I should check it in; don't want to step on people.

2) The way ClusterConfigMetaData.determineHome(Bean)LoadBalancingPolicy() work, you only get the default policy if you added a cluster-config element to your bean declaration in jboss.xml.  If the ClusterConfigMetaData came from a container-configuration, you *don't* get any default.  You get null unless the value was specifically set in the relevant container-configuration/cluster-config element. This leads to test failures.  A simple workaround to fix the test failures is to add the default policies to standardjboss.xml.

3) (I could be wrong about this; haven't tested, just looked at code. So, take this as more about how it should work). If you do something like this:

In jboss.xml:


  | <!-- A clustered SLSB -->
  | <session>
  |       ... ...
  |      <clustered>true</clustered>
  |      <cluster-config>
  |        <partition-name>MyPartition</partition-name>
  |      </cluster-config>
  | </session>
  | 

In standardjboss.xml:


  | <container-configuration>
  |      <container-name>Clustered Stateless SessionBean</container-name>
  |      ... ...
  |      <cluster-config>
  |          <partition-name>${jboss.partition.name:DefaultPartition}</partition-name>         
  |          <!-- Use RANDOM ROBIN!!! -->
  |          <home-load-balance-policy>
  |               org.jboss.ha.framework.interfaces.RandomRobin
  |          </home-load-balance-policy>         
  |          <bean-load-balance-policy>
  |             org.jboss.ha.framework.interfaces.RoundRobin
  |          </bean-load-balance-policy>
  |      </cluster-config>
  | </container-configuration>
  | 

Your bean will end up using RoundRobin instead of RandomRobin.  AFAICT, the code checks the bean's config, and if not set goes to a hard coded default.

Wouldn't it be better to pull the default from the container-configuration?  If that's agreeable I can do that.

4) If yes to last question, that suggests there shouldn't be a hard coded default at all; the defaults should come from a container-configuration, ultimately from standardjboss.xml.

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