Hey kevin, i just found that part of this thread went to my junk folder. can you send the URL for the NodeListener?
this NodeWatcher is a useful thing. i have a couple of suggestions to simplify it: 1) Construct the NodeWatcher with a ZooKeeper object rather than constructing one. Not only does it simplify NodeWatcher, but it also makes it so that the ZooKeeper object can be used for other things as well. 2) Use the async API in watchNodeData and watchNodeExists. it simplifies the code and the error handling. 3) You don't need to do a connect() in handleDisconnected(). ZooKeeper object will do it automatically for you. There is an old example on sourceforge http://zookeeper.wiki.sourceforge.net/ZooKeeperJavaExample that may give you some more ideas on how to simplify your code. thanx ben ________________________________________ From: burtona...@gmail.com [burtona...@gmail.com] On Behalf Of Kevin Burton [bur...@spinn3r.com] Sent: Thursday, January 08, 2009 12:00 AM To: zookeeper-user@hadoop.apache.org Subject: Updated NodeWatcher... I've updated based on the last round of feedback regarding ZK operation: http://pastebin.com/f66898b7 This is what I think the API should look like for event based applications without any insane requirements. You write code like: NodeListener listener = new NodeListener() { public void onData( String path, Stat stat, byte[] data ) { System.out.printf( "event: onData path: %s, version: %s, data: %s\n", path, stat.getVersion(), new String( data ) ); } public void onKeeperException( KeeperException e ) { System.out.printf( "event: onKeeperException: \n" ); e.printStackTrace(); } public void onFailure() { System.out.printf( "event: onFailure\n" ); } public void onConnect() { System.out.printf( "event: onConnect\n" ); } }; NodeWatcher nWatcher = new NodeWatcher( "server45.example.com:2181, server46.example.com:2181,server47.example.com:2181", listener ); nWatcher.watch( "/foo" ); nWatcher.poll(); .... and then you will receive events back from ZK when the files are updated. I believe it handles all race and fail conditions of ZK which was the hard part since some of these are subtle or not really documented. I'd be willing to contrib this if others found it useful. I think we're going to use it as our main interface to ZK since it solves all the issues I care about. Kevin -- Founder/CEO Spinn3r.com Location: San Francisco, CA AIM/YIM: sfburtonator Skype: burtonator Work: http://spinn3r.com
