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Patrick Hunt commented on ZOOKEEPER-1381: ----------------------------------------- bq. these versions can change if the ZK administrator is currently upgrading/downgrading this cluster. I'd say it's a mistake for the admin make changes to the cluster w/o notifying the users. At the very least you're going to want to test in a staging environment before rolling out such a change to production. bq. So if I sum up everything ... I personally don't like the nc idea. Having your client do this sounds fishy to me. How about the following. If you implemented the fix I originally suggested (have the server handle this case, really it's a bug that's not happening now) then the server would at least return an error (perhaps org.apache.zookeeper.KeeperException.APIErrorException?) to the client and log the problem. Likely it should also close the session. What do you think? Wouldn't that be sufficient for what you've described? > Add a method to get the zookeeper server version from the client > ---------------------------------------------------------------- > > Key: ZOOKEEPER-1381 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1381 > Project: ZooKeeper > Issue Type: Improvement > Components: c client, documentation, java client, server > Affects Versions: 3.4.2 > Environment: all > Reporter: nkeywal > Priority: Minor > Labels: newbie > > Zookeeper client API is designed to be server version agnostic as much as > possible, so we can have new clients with old servers (or the opposite). But > there is today no simple way for a client to know what's the server version. > This would be very useful in order to; > - check the compatibility (ex: 'multi' implementation available since 3.4 > while 3.4 clients API supports 3.3 servers as well) > - have different implementation depending on the server functionalities > A workaround (proposed by Mahadev Konar) is do "echo stat | nc hostname > clientport" and parse the output to get the version. The output is, for > example: > ----------------------- > Zookeeper version: 3.4.2--1, built on 01/30/2012 17:43 GMT > Clients: > /127.0.0.1:54951[0](queued=0,recved=1,sent=0) > Latency min/avg/max: 0/0/0 > Received: 1 > Sent: 0 > Outstanding: 0 > Zxid: 0x500000001 > Mode: follower > Node count: 7 > -------------------- -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira