What's I believe is happening here is as follows:
When you look up your SLSB in JNDI, the servlet actually downloads a
cluster-aware proxy to the EJB. The proxy includes information about the
topology for that EJB, i.e. that it is deployed on {Y, Z}.
That topology gets updated 1) whenever you make a request that fails (node that
failed is remove from list on client side) 2) if you make a request that
succeeds and the server detects that your client side proxy is out of sync with
what the server knows 3) if you download a new proxy by doing a new JNDI lookup.
So, let's go through your scenario, showing what the client sees as the cluster
topology, and what the server side situation actually is.
Legend for the following:
Action : { client-side view of topology } : {actual server-side topology}
So:
1) download proxy via JNDI lookup : { Y, Z } : { Y, Z}
2) make request: { Y, Z } : { Y, Z}
3) kill Y, request fails over to Z: { Z } : { Z}
4) start Y, request to Z ongoing: { Z} : { Y, Z }
5) kill Z, ongoing request to Z aborted: {} : { Y, Z }
In step 4/5, your client never made a new request to the cluster so it was
never informed that Y was available. When Z fails, the client sees no
available servers and fails.
If you had made a new request to Z after step 4 but before 5, you would have
gotten a new topology { Y, Z }, and then failover would have worked in step 5.
If you did a new JNDI lookup you'd also get an updated topology.
Our EJB2 clustering code has a feature called the RetryInterceptor that can
deal with this situation. See http://wiki.jboss.org/wiki/RetryInterceptor .
There is no analogue yet for EJB3, as the way the proxies work is different.
JIRA for adding one is http://jira.jboss.com/jira/browse/EJBTHREE-1002 .
View the original post :
http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4142232#4142232
Reply to the post :
http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4142232
_______________________________________________
jboss-user mailing list
[email protected]
https://lists.jboss.org/mailman/listinfo/jboss-user
