[infinispan-dev] Design of Remote Hot Rod events

[Galder Zamarreño]

On Nov 19, 2013, at 2:49 AM, Mircea Markus <mmarkus at redhat.com> wrote:

> Nice work!
> 
> Few questions:
> - in the context of near-caching, entry-modified and entry-deleted would have the same effect on the client: invalidation of data. If near-caching is our main goal, we might as well send a single notification type (entry-modified) for both modification and deletion (the deletion is just a particular case of modification). Just an idea.

There's a difference between an update and a delete. The update can carry the latest version of the entry in memory, which could be of use to the client, if for example they want to do a replace() as long as the version has not changed. The delete would not have that info since the entry is gone. I think it's more logical to have both separate.

> - how does the server know that a request originated from a certain client in order not to send it to that client again? There's no clientId in the request…

Well spotted :). There are two ways to solve this. 

First one is by adding the source id to each cache operation sent from the client. This would require a change in the way the header is parsed for all operations. This is the simplest solution, with a little addition to the header.

The second option is a bit more complicated but avoids the need to send the source id per request. At least in the Java client, each connection opened sends a ping at the start. You could add source id to the ping command, and then the server could track all incoming connections that send a particular id. There could be multiple in the case of clients pooling connections. The server can track disconnections and keep this collection up to date, but it'd be quite a bit of work on top of the rest of stuff.

I'd prefer the first option.

Cheers,

> 
> 
> On Nov 12, 2013, at 3:17 PM, Galder Zamarreño <galder at redhat.com> wrote:
> 
>> Hi all,
>> 
>> Re: https://github.com/infinispan/infinispan/wiki/Remote-Hot-Rod-Events
>> 
>> I've just finished writing up the Hot Rod remote events design document. Amongst many other use cases, this will enable near caching use cases with the help of Hot Rod client callbacks.
>> 
>> Cheers,
>> --
>> Galder Zamarreño
>> galder at redhat.com
>> twitter.com/galderz
>> 
>> Project Lead, Escalante
>> http://escalante.io
>> 
>> Engineer, Infinispan
>> http://infinispan.org
>> 
>> 
>> _______________________________________________
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> 
> Cheers,
> -- 
> Mircea Markus
> Infinispan lead (www.infinispan.org)
> 
> 
> 
> 
> 
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--
Galder Zamarreño
galder at redhat.com
twitter.com/galderz

Project Lead, Escalante
http://escalante.io

Engineer, Infinispan
http://infinispan.org