RE: [jbosscache-dev] easing the path for clients to getaroundredeployment class loading issues in JBC

I have just tried it with a local cache and it worked. One of the customers was using JBC 1.0, so the work was not in vain :) It might be worth adding the redeployment case to the documentation in the marshaller section. Galder Zamarreño Sr. Software Maintenance Engineer JBoss, a division of Red Hat -----Original Message----- From: jbosscache-dev-bounces(a)lists.jboss.org [mailto:jbosscache-dev-bounces@lists.jboss.org] On Behalf Of Galder Zamarreno Sent: 02 November 2006 16:31 To: Brian Stansberry; jbosscache-dev(a)lists.jboss.org Subject: RE: [jbosscache-dev] easing the path for clients to getaroundredeployment class loading issues in JBC I did suggest this to Manik, but he told me that marshalling would not work on local caches, but only in replicated ones. I might have misunderstood him. The doc focuses on the state transfer issues when class loaders are not still available. Galder Zamarreño Sr. Software Maintenance Engineer JBoss, a division of Red Hat -----Original Message----- From: Brian Stansberry Sent: 02 November 2006 15:58 To: Galder Zamarreno; jbosscache-dev(a)lists.jboss.org Subject: RE: [jbosscache-dev] easing the path for clients to get aroundredeployment class loading issues in JBC There's already an API for this kind of use case. I'm going to speak in 1.x terms here: // Config for cache startup TreeCache.setUseRegionBasedMarshalling(true); TreeCache.inactiveOnStartup(true); // suppresses initial state transfer // Deploy phase -- app creates a region and registers it's classloader TreeCache.registerClassloader(Fqn, ClassLoader); // Then transfer the state for the region, since you've now go the correct classloader TreeCache.activateRegion(Fqn); // Operate normallly // Undeploy phase -- deactivate the region, which evicts all nodes TreeCache.inactivateRegion(Fqn) // Don't leak a classloader ref TreeCache.unregisterClassloader(Fqn); - Brian jbosscache-dev-bounces(a)lists.jboss.org wrote: > Hi, > > I have seen couple of people with the same issue in the past few > weeks. I already had a chat with Manik but it was more about solving > the problem at the time rather than thinking how we can make it > easier for the customers to get around it. > > Applications which are redeployed and interact with the cache are > quite likely to encounter class loading issues. They tend to enter > data in the cache, they get redeployed, try accessing the data > entered previously and you end up with a ClassCastException. > > For caches managed by Hibernate, this is not a problem cos Hibernate > does the cleanup on undeployment, asking clients to close the > session. > > In the rest of cases, clients have to iterate over evict() calls. > This will be solved in JBC 2.0 with evictSubtree() method that can > be recursive. > > However, clients still need to code an MBean which is part of the > lifecycle of the deployment, and upon destroy, it calls > evictSubtree(). > > The cache configuration would have to depend on this MBean in case > the cache deployment is done inside the client's application. > Otherwise, we could assume that undeployment of JBC is quite likely > due to AS undeployment in which case there's no need for cleanup. > > Have you got any ideas of anything else that could be done in JBC to > help speed up this implementation and make it less of daunting task > for the customer? > > I guess the main part is documenting all this. > > Galder Zamarreño > Sr. Software Maintenance Engineer > JBoss, a division of Red Hat