[jboss-as7-dev] EJB passivation/activation, clustering and JPA extended persistence context handling...

[Jason T. Greene]

On 12/2/11 2:55 PM, Scott Marlow wrote:
>> We also know that we need to replicate the serialization group (as its
>> definition changes dynamically).  For example, the application has five
>> stateful session beans (SFSB1-SFSB5) that are associated with three
>> extended persistence contexts (XPC1-XPC3).  The relationships between
>> these five beans are as follows:
>>
>>      SFSB1 uses XPC1
>>      SFSB2 uses XPC1 and has reference to SFSB3
>>      SFSB3 uses XPC2
>>      SFSB4 uses XPC2 and has reference to SFSB5
>>      SFSB5 uses XPC3
>>
>> When SFSB1 fails over, we need to fail-over its working set (the
>> serialization group which includes SFSB1, SFSB2, SFSB3, SFSB4, SFSB5,
>> XPC1, XPC2, XPC3).  In case its not obvious why, SFSB2 may have pending
>> database updates in XPC1, so it must fail-over also to the same target
>> node.  Since SFSB2 has a reference to SFSB3, SFSB3 needs to fail-over
>> together with the group also (and so the pattern continues for SFSB4,
>> SFSB5, XPC3).
>
> The above is the application correctness issue.  If SFSB2 fails over to
> a different node than SFSB4, the extended persistence context could be
> used on two different nodes.  Basically, the extended persistence
> context can live through several non-transactional invocations.  When a
> transaction is finally started on SFSB3 or SFSB4, the XPC2 changes will
> finally be committed.

I still don't this is right. those references go across a proxy, and the 
proxy's backing data can be anywhere.

-- 
Jason T. Greene
JBoss AS Lead / EAP Platform Architect
JBoss, a division of Red Hat