Environment: JBoss 3.2.6/JDK 1.4_05/Win2K Server/JMS using HTTPIL
Scenario: A client creates and subscribes to a temporary topic. The
client then exits without deleting the temporary topic.
Problem: The temporary topic still exists on the server (leaked) along
with any unclaimed messages and any future messages posted to that topic.
Due to the asynchronous nature of the HTTPIL connection, there is no way for
the server to directly detect demise of a client and clean up temporary
destinations created by that client. Any temporary destinations left behind
by a client upon exit are leaked (along with any messages left on those
One can plug in a ClientMonitorInterceptor to time out inactive connections,
which will effect cleanup of temporary destinations, but this is not without
its own problems.
Timing out a connection by this means does invoke the asynchClose() method on
the Connection bject on the client. But, that method does nothing. So, there
is no way for the HTTPClientILService.run() method to detect that the connection
has been closed (in the case where the connection is closed but the client is
still receiving on it). Further, the HTTPClientILService.run() method does not
check to see if the Connection has closed anyway. The HTTPClientILService.run()
continues looping making calls to the HttpILServerServlet to pick up any waiting
messages even after the ClientConnectionMonitor has closed the connection. The
result is that the client is unable to detect closure of the connection and
does not receive a failure notification from the receive call as might be
Another issue is that the HTTPIL does not implement pings so there is no
automatic way to keep the connection alive if there is no traffic on
the connection (on a dormant connection, the ClientMonitorInterceptor
would eventually close the connection). Setting the PingPeriod in the
jboss-service.xml service descriptor is ineffective due to the following
overriding code in HTTPServerILService.startService() :
public void startService() throws Exception
this.pingPeriod = 0; // We don't do pings.
If a "ping" of some sort is to be performed, it becomes the responsibility
of the client application.
Perhaps more desirable beahvior would be:
1) Connection-managed pinging to be supported for HTTPIL
2) Some means of notifying a listening consumer that the connection has timed
out - why should a consumer be allowed to invoke the HTTPIlServerServlet and
wait for messages that will never come (because the connection has been closed)
Is this behavior to be considered a bug in the HTTPIL implementation, or
merely an inconvenience that I should be able to devise a workaround for?
Any suggestions on how best to handle this problem?