Hi,

I still don't think that the document covers properly the description of failover.

My understanding is that client registers clustered listeners on one server (the first one it connects, I guess). There's some space for optimization, as the notification will be sent from primary owner to this node and only then over hotrod to the client, but I don't want to discuss it now.

> Listener registrations will survive node failures thanks to the underlying clustered listener implementation.

I am not that much into clustered listeners yet, but I think that the mechanism makes sure that when the primary owner changes, the new owner will then send the events. But when the node which registered the clustered listener dies, others will just forgot about it.

> When a client detects that the server which was serving the events is gone, it needs to resend it’s registration to one of the nodes in the cluster. Whoever receives that request will again loop through its contents and send an event for each entry to the client.

Will that be all entries in the whole cache, or just from some node? I guess that the first is correct. So, as soon as one node dies, all clients will be bombarded by the full cache content (ok, filtered). Even if these entries have not changed, because the cluster can't know.

> This way the client avoids loosing events. Once all entries have been iterated over, on-going events will be sent to the client.

> This way of handling failure means that clients will receive at-least-once delivery of cache updates. It might receive multiple events for the cache update as a result of topology changes handling.

So, if there are several modifications before the client reconnects and the new target registers the listener, the clients will get only notification about the last modification, or rather just the entry content, right?

Radim


On 04/02/2014 01:14 PM, Galder Zamarreño wrote:
Hi all,

I’ve finally managed to get around to updating the remote hot rod event design wiki [1].

The biggest changes are related to piggybacking on the cluster listeners functionality in order to for registration/deregistration of listeners and handling failure scenarios. This should simplify the actual implementation on the Hot Rod side.

Based on feedback, I’ve also changed some of the class names so that it’s clearer what’s client side and what’s server side.

A very important change is the fact that source id information has gone. This is primarily because near-cache like implementations cannot make assumptions on what to store in the near caches when the client invokes operations. Such implementations need to act purely on the events received.

Finally, a filter/converter plugging mechanism will be done via factory implementations, which provide more flexibility on the way filter/converter instances are created. This opens the possibility for filter/converter factory parameters to be added to the protocol and passed, after unmarshalling, to the factory callbacks (this is not included right now).

I hope to get started on this in the next few days, so feedback at this point is crucial to get a solid first release.

Cheers,

[1] https://github.com/infinispan/infinispan/wiki/Remote-Hot-Rod-Events
--
Galder Zamarreño
galder@redhat.com
twitter.com/galderz

Project Lead, Escalante
http://escalante.io

Engineer, Infinispan
http://infinispan.org


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-- 
Radim Vansa <rvansa@redhat.com>
JBoss DataGrid QA