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From Patrick Hunt <ph...@apache.org>
Subject Re: DISCONNECTED and SESSION_EXPIRED events
Date Wed, 11 Apr 2012 05:34:13 GMT
On Tue, Apr 10, 2012 at 6:41 PM, Rohan Desai <desai.p.rohan@gmail.com> wrote:
> Im new to zk and had some questions about connection loss events. From what
> I understand when a ZK handle loses connection to the ZK cluster, the ZK
> client's watch handler receives a DISCONNECTED event. If the connection is
> lost for longer than the session timeout, the ZK client's watch handler
> receives a SESSION_EXPIRED event and the handle is closed. If this is
> correct, does the ZK client's watch handler receive the DISCONNECTED event
> right after the client loses its connection to the cluster? When does the
> client get the SESSION_EXPIRED event? Does it get it after the client
> detects the session would have timed out or only after the client is able
> to re-establish a connection to the ZK cluster?

Some good details in the faq on this:
https://cwiki.apache.org/confluence/display/ZOOKEEPER/FAQ

It's not exactly as you describe - for example you can't know the
session is expired until you reconnect to the server.

Also see this section in the programmer guide:
http://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#ch_zkSessions

Patrick

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