[jboss-jira] [JBoss JIRA] Commented: (JBAS-4455) LoadBalancePolicy that tries to pin all requests associated with a tx to one server

[Galder Zamarreno (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBAS-4455?page=comments#action_12382040 ] 
            
Galder Zamarreno commented on JBAS-4455:
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[private]

Another potential customer interested in this feature:
https://na1.salesforce.com/50030000003i3bC

> LoadBalancePolicy that tries to pin all requests associated with a tx to one server
> -----------------------------------------------------------------------------------
>
>                 Key: JBAS-4455
>                 URL: http://jira.jboss.com/jira/browse/JBAS-4455
>             Project: JBoss Application Server
>          Issue Type: Feature Request
>      Security Level: Public(Everyone can see) 
>          Components: Clustering
>            Reporter: Brian Stansberry
>         Assigned To: Galder Zamarreno
>            Priority: Minor
>
> The HA proxies don't allow failover once a tx has reached a server.  This can lead to this kind of situation:
> EJB A deployed on nodes 1 and 2.
> EJB B deployed on nodes 1 and 2.
> 1) Start tx, invoke on A.1.
> 2) Lookup B.
> 3) Invoke on B. LB policy picks B.2
> 4) Node 2 is dead for some reason so call fails.
> 5) Can't fail over because tx context won't allow a failover after a call has reached a server.
> But, B.1 is fine and is running on the only node the tx has invoked on. :(
> Approach to improving this.  This is based on JRMPInovkerProxyHA methods, but the idea is generic:
> In invocationHasReachedAServer, instead of storing null as the value, you store the target (key is the tx).
> In invoke, if there's a tx, you add that target (if there is one) to the invocation as transient metadata 
> The LB policy gets passed the invocation as an arg when it chooses a target (this is already in the API)
> LB policy checks for the metadata. If there, and that target is in its target list, return that target

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