Session Replication Valve & Cross Context Dispatching

[Eric Dalquist <ed...@unicon.net>]

I have been working on getting session replication working for a set of 
web applications that use cross context dispatching.

I ran into a problem where the session for the context the request is 
being made to is being replicated correctly but the session for the 
context(s) being dispatched to are not being replicated at all.

The contextA servlet handling the request modifies its session then does 
a cross context dispatch to another servlet in contextB which also 
modifies its session. In this case two different sessions (one for 
contextA and another for contextB) have been modified. After the request 
is complete only the contextA session is replicated.

After a fair amount of digging into the tomcat code I think I have an 
understanding of how session replication works and what is going on in 
this case.

The following stack trace was captured just before the servlet in 
contextB is called. The stack items above and below the lines is tomcat 
code.

 From what I've been able to figure out configuring Clustering in tomcat 
adds the ReplicationValve to the chain of valves the request goes 
through before getting to the servlet. After the servlet is called this 
valve calls the Manager for this context to inform it the request is 
complete and that replication should be done. The ReplicationValve is in 
the bottom 1/3 of the stack.

In the top 1/3 of the stack is the tomcat code to execute a cross 
context dispatch. There is no ReplicationValve or other filter in this 
stack so after the dispatch is complete there is no code called to 
inform the manager of the other context that the request is complete and 
replication should be performed.

Is there any way to get tomcat to replicate the session for contexts 
that are accessed via cross context dispatches during a request?

Thank you
    -Eric Dalquist

Thread [TSP-Processor3] (Suspended)
   ApplicationFilterChain.internalDoFilter(ServletRequest, 
ServletResponse) line: 234
   ApplicationFilterChain.doFilter(ServletRequest, ServletResponse) 
line: 173
   ApplicationDispatcher.invoke(ServletRequest, ServletResponse) line: 672
   ApplicationDispatcher.doInclude(ServletRequest, ServletResponse) 
line: 574
   ApplicationDispatcher.include(ServletRequest, ServletResponse) line: 499
--------------------------------------------------------------------------
   PortletInvokerImpl.invoke(PortletRequest, PortletResponse, Integer) 
line: 120
   PortletInvokerImpl.action(ActionRequest, ActionResponse) line: 68
   PortletContainerImpl.processPortletAction(PortletWindow, 
HttpServletRequest, HttpServletResponse) line: 150
   CPortletAdapter.setRuntimeData(ChannelRuntimeData, String) line: 578
   
MultithreadedPrivilegedCacheableDirectResponseCharacterChannelAdapter(MultithreadedCharacterChannelAdapter).setRuntimeData(ChannelRuntimeData) 
line: 29
   ChannelManager.feedRuntimeDataToChannel(IChannel, HttpServletRequest) 
line: 896
   ChannelManager.processRequestChannelParameters(HttpServletRequest) 
line: 841
   ChannelManager.startRenderingCycle(HttpServletRequest, 
HttpServletResponse, UPFileSpec) line: 981
   UserInstance.processPortletActionIfNecessary(HttpServletRequest, 
HttpServletResponse) line: 203
   UserInstance.writeContent(HttpServletRequest, HttpServletResponse) 
line: 177
   PortalSessionManager.doGet(HttpServletRequest, HttpServletResponse) 
line: 253
   PortalSessionManager(HttpServlet).service(HttpServletRequest, 
HttpServletResponse) line: 689
   PortalSessionManager(HttpServlet).service(ServletRequest, 
ServletResponse) line: 802
--------------------------------------------------------------------------
   ApplicationFilterChain.internalDoFilter(ServletRequest, 
ServletResponse) line: 252
   ApplicationFilterChain.doFilter(ServletRequest, ServletResponse) 
line: 173
   StandardWrapperValve.invoke(Request, Response) line: 213
   StandardContextValve.invoke(Request, Response) line: 178
   StandardHostValve.invoke(Request, Response) line: 126
   ReplicationValve.invoke(Request, Response) line: 145
   ErrorReportValve.invoke(Request, Response) line: 105
   StandardEngineValve.invoke(Request, Response) line: 107
   CoyoteAdapter.service(Request, Response) line: 148
   JkCoyoteHandler.invoke(Msg, MsgContext) line: 307
   HandlerRequest.invoke(Msg, MsgContext) line: 385
   ChannelSocket.invoke(Msg, MsgContext) line: 748
   ChannelSocket.processConnection(MsgContext) line: 678
   SocketConnection.runIt(Object[]) line: 871

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