Store your PEMs in a known path. Or, store a known value in the node. -JZ
> On Oct 14, 2015, at 5:49 PM, Vikrant Singh <[email protected]> > wrote: > > What I want is to differentiate between "ephemeral nodes" and "persistent > ephemeral node". > > On Wed, Oct 14, 2015 at 3:20 PM, Cameron McKenzie <[email protected] > <mailto:[email protected]>> wrote: > You could keep track of which nodes are ephemeral by looking at the stat > object passed to the NODE_ADDED event in the TreeCache. Then when you get a > NODE_REMOVED event you could check if it's one of your ephemeral nodes? > > On Thu, Oct 15, 2015 at 4:06 AM, Vikrant Singh <[email protected] > <mailto:[email protected]>> wrote: > yes you got it correct... a slight correction. I am trying to find a way > where I can make my tree cache event handler aware that "node removed" event > is coming from a persistent ephemeral node and delay any action till the > point the node's curator framework gives up on rewriting the node to ZK. > > On Mon, Oct 12, 2015 at 3:38 PM, Cameron McKenzie <[email protected] > <mailto:[email protected]>> wrote: > So, if I'm understanding correctly, if your application loses its connection > to ZooKeeper (or crashes), then a new instance will be started in its place, > and if the original instance reconnects then you don't want it to try and > recreate its ephemeral node? > > If that's the case, then I think that you need additional logic beyond what a > PersistentEphemeralNode is going to provide you, as you will need to check if > the node already exists on reconnection. > > On Tue, Oct 13, 2015 at 8:43 AM, Vikrant Singh <[email protected] > <mailto:[email protected]>> wrote: > yeah I considered that.. but I ended up using tree cache because it gives me > more control on the state of tree . I have some custom handlers for > add/remove/update events. Same cache is also used for service discovery. > > On Mon, Oct 12, 2015 at 2:33 PM, David Kesler <[email protected] > <mailto:[email protected]>> wrote: > There’s also already a Curator service discovery extension library that you > can look at: http://curator.apache.org/curator-x-discovery/index.html > <http://curator.apache.org/curator-x-discovery/index.html>. It’s basically > boiling down to the same strategy of sticking an ephemeral node into ZK, but > with some additional convenience and functionality built on top of it. > > > > From: Cameron McKenzie [mailto:[email protected] > <mailto:[email protected]>] > Sent: Monday, October 12, 2015 5:05 PM > To: [email protected] <mailto:[email protected]> > Subject: Re: Persistent Ephemeral Node > > > > hey Vikrant, > > Using a persistent ephemeral node just means that your application code > doesn't need to worry about handling recreation of the node when it > reconnects to ZooKeeper after connection / session loss. > > > > If your ephemeral node should always be present whenever your application > instance is running, then this would be a good use case for a persistent > ephemeral node. > > cheers > > > > > > On Tue, Oct 13, 2015 at 6:03 AM, Vikrant Singh <[email protected] > <mailto:[email protected]>> wrote: > > I have some basic question on persistent ephemeral node. > > Here is some background... > > > > We have a zoo keeper based service discovery setup. Each service register > itself as a ephemeral node with zookeeper.When a service go down its > ephemeral node is removed from zookeeper and we know that service is down and > we provision it again. > > At present we create plain ephemeral node. I am wondering what benefit/risks > we may get if move to persistent ephemeral ones. I see one problem... using > plane ephemeral node we can rely on state of ZK to make a decision like > service is down. This is because we are sure that if a node get deleted with > zoo keeper it will never comeback from same process. But if moved to > "persistent ephemeral" I guess same may not be the case. > > > > Please let me know what you think of the same. > > > > Also I would like to know what are the best scenario where one should prefer > using persistent ephemeral node over ephemeral node. > > > > Thanks, > > Vikrant > > > > > > > >
