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From "Andrei Savu (JIRA)" <j...@apache.org>
Subject [jira] Created: (ZOOKEEPER-834) Allow ephemeral znodes to have children created only by the owner session.
Date Fri, 06 Aug 2010 19:59:18 GMT
Allow ephemeral znodes to have children created only by the owner session. 
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                 Key: ZOOKEEPER-834
                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-834
             Project: Zookeeper
          Issue Type: New Feature
          Components: c client, java client, server
            Reporter: Andrei Savu
             Fix For: 3.4.0


Ephemeral znodes are automatically removed when the client session is closed or expires and
this behavior makes them very useful when you want to publish status information from active
/ connected clients. 

But there is a catch. Right now ephemerals can't have children znodes and because of that
clients need to serialize status information as byte strings. This serialization renders that
information almost invisible to generic zookeeper clients and hard / inefficient to update.


Most of the time the status information can be expressed as a bunch of (key, value) pairs
and we could easily store that using child znodes. Any ZooKeeper client can read that info
without the need to reverse the serialization process and we can also easily update it. 

I suggest that the server should allow the ephemeral znodes to have children znodes. Each
child should also be an ephemeral znode owned by the same session - parent ephemeralOwner
session.

Mail Archive: 
http://www.mail-archive.com/zookeeper-dev@hadoop.apache.org/msg09819.html

Another discussion about the same topic:
http://www.mail-archive.com/zookeeper-dev@hadoop.apache.org/msg08165.html


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