[jboss-cluster-dev] Re: JBoss Remoting feed back (Was: Re: Apache MINA slides for this year's JavaOne)

[Galder Zamarreno]

Trustin/Ron,

Currently, org.jboss.remoting.Client does not contain a getLocator() 
method which I suspect is the reason why UnifiedInvokerProxy ends up 
having a reference to org.jboss.remoting.Client and a reference to 
org.jboss.remoting.InvokerLocator.

In a non clustered environment, the fact that we maintain a Client and 
Locator on the client side is not a big problem, but in a clustered 
environment, for example if using Round Robin, the client and the 
locator keep changing from invocation to invocation.

Bottom line is that we're having to synchronize on UnifiedInvokerHAProxy 
to make sure that the update of the InvokerLocator and Client are 
atomic. See the following JIRAs for issues we had to resolve around this 
area:

http://jira.jboss.com/jira/browse/JBAS-4815
http://jira.jboss.com/jira/browse/JBAS-5364

With the complete rewrite, such problem might not even be relevant, but 
I think it's important that we get it resolved when Remoting 3 is 
designed. Unified invokers should only need to keep a reference to a 
single thread safe client Remoting instance.

Maybe what we need of Remoting's Client class is not only getLocator() 
but more importantly, an atomic method that is able to check whether 
we're connected somewhere and if not, connect to it, in similar fashion 
to putIfAbsent().

This is effectively what UnifiedInvokerHAProxy.getClient() is doing 
after selecting the target node from the clustered load balancer. IMO, 
it's Remoting that should be providing with a thread safe API to do this.

Thoughts?

Cheers,

Trustin Lee wrote:
> Hi Luc et al,
> 
> I am interested in everyone's feed back based on your experience with
> Remoting.  I'd like to hear what was good and bad so we can fix as much
> as possible in Remoting 3, which is a rewrite of Remoting 2 with whole
> new API.
> 
> Thanks in advance,
> 
> Luc Texier wrote:
>> Sounds very promising Trustin, great job!
>>
>> If you want feedback and suggestions on MINA based on our (painful) experience with JBoss Remoting, feel free to contact the support team here in cc.
>>
>> Cheers,
>>
>>
>>
>> On Mon, 14 Apr 2008 15:46:43 +0200, Trustin Lee <tlee at redhat.com> wrote:
>>
>>> Hi,
>>>
>>> The attached PDF file is my slides for this year's JavaOne.  You might
>>> be interested in this if you want to see what MINA is from examples
>>> instead of vague propaganda. :)
>>>
>>> Any feed back or question is also appreciated.
>>>
>>> Please keep the file confidential until my session starts.  It's on
>>> Friday.  ;)
>>>
>>> Thanks,
>>
>>
> 

-- 
Galder Zamarreño
Sr. Software Maintenance Engineer
JBoss, a division of Red Hat