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From Harsh J <ha...@cloudera.com>
Subject Re: zookeeper discussion on watches.
Date Tue, 21 Aug 2012 09:31:08 GMT
Hi Sunil,

Have you gone over the developer's guide docs on the website:
http://zookeeper.apache.org/doc/trunk/zookeeperProgrammers.html#ch_zkWatches?
It is pretty simple to use watches and the text on that page should
almost be all you need to use it.

Also, the zkCli.sh CLI program does show how to set a watch when you
type "help" on it:

> get path [watch]

So for example, if you want to set a watch from the CLI on the znode
/hbase/master, you may do:

> get /hbase/master true

(The new CLI format on trunk is to do as "get -w /hbase/master"
instead. But the above should work and warn even if you are on trunk
today.)

Then if "printwatches" is on (it is on by default), you should be able
to see any changes made to that znode by other processes.

For instance, if I deleted the node via a "delete /hbase/master", I'd
see this on the shell:

WATCHER::

WatchedEvent state:SyncConnected type:NodeDeleted path:/hbase/hbaseid

Hope this helps!

On Tue, Aug 21, 2012 at 1:19 PM, sunil singh <sunilsingh0032@yahoo.com> wrote:
> Hi guys... m working on zookeeper and its really difficult to find something
> precise on watches.
> So lets start on discussion on watches from beginning so that all the
> developer around the world get help and share their experience.
> Q.1) how to set watch on a znode so that clients are notified when the data
> of the znode changes.
>
>
>
> --
> View this message in context: http://zookeeper-user.578899.n2.nabble.com/zookeeper-discussion-on-watches-tp7577815.html
> Sent from the zookeeper-user mailing list archive at Nabble.com.



-- 
Harsh J

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