http://jakarta.apache.org/builds/jakarta-tomcat-connectors/jk/release/v1.2.0/doc/jk/workershowto.html
contains the following text:
'We need a graceful shut down of a node for maintenance. The balancer in front asks a special port on each node periodically. If we want to remove a node from the cluster, we switch off this port. The loadbalancer can't connect to it and marks the node as down. But we don't move the sessions to another node. In this environment it is an error if the balancer sends a request without a session to an apache+mod_jk+tomcat which port is switched off. And if the load balancer determines that a node is down no other node is allowed to send a request without a session to it. Only requests with old sessions on the switched off node would be routed to this node. After some time nobody uses the old sessions and the sessions will time out. Then nobody uses this node, because all session are gone and the node is unreachable without a session-id in the request. If someone uses a session which timed out, our servlet system sends a redirect response without a session id to the browser. This is necessary for me, because on a switched off node apache and tomcat can still be up and running, but they are in an old state and should only be asked for valid old sessions. After the last session timed out, I could update the node etc. without killing sessions or moving them to another node. Sometimes we have a lot of big objects in our sessions, so it would be really time consuming to move them.'
My reading of this is that I can dynamically tell TC to stop accepting new sessions. It will notify mod_jk and thenceforth only requests already bound to existing sessions hosted in this TC instance will be forwarded from mod_jk.
I have scoured the web, mailing list archives and src code, most likely with the wrong keywords, trying to find references explaining, how I can tell TC that I want to bleed the existing sessions off it, using this functionality.
I understand and use the support for session affinity via jvmRoute and other worker properties. I would now like to extend what I have to support the graceful shutdown on TC nodes without the loss of session data. I do not want to persist or otherwise distribute these sessions.
Can anyone point me in the right direction ?
Thanks for your time,
Jules
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