Check out ZKClient: https://github.com/sgroschupf/zkclient
The way this client deals with sessions is pretty nice and clean and I ended up using a lot of this code as the basis for my Java client. C -----Original Message----- From: Gustavo Niemeyer [mailto:gust...@niemeyer.net] Sent: Thursday, November 18, 2010 1:26 PM To: zookeeper-user@hadoop.apache.org Subject: Session events Hello again, Even though we've been using ZooKeeper for some time, just now we're stopping and thinking through to see how to best deal with session events in the context of a whole application. To ensure I'm not off track, my understanding of session and session event handling is: 1) It is an error to attempt to use a zk connection before a session is established. 2) Session events can *only* be observed by setting a watch explicitly, so one has to do something similar to wexists("/", observe_change_func) in their preferred client API to set a hook which will purposefully wait on a session change. 3) *All* the existing watches receive session events. 4) Reconnections within the grace period will not cause a session event. First, are these statements correct? Then, how are people generally architecting reliable applications when facing these facts? Are you simply checking for type == SESSION_EVENT on *all* the watching functions? Are you using a single watching function and perhaps redirecting the flow to a different location after freeing the used resources? Are you ignoring the issue entirely and hoping for the best? :-) Any insights into existing practices will be welcome. -- Gustavo Niemeyer http://niemeyer.net http://niemeyer.net/blog http://niemeyer.net/twitter
