Re: Asynchonrous and synchronous messages on same channel

Tim Fox wrote:
>
> Bela Ban wrote:
>
>> Note that you can use the Dispatcher to do both anyway: castMessage()
>> has a mode parameter, which can get GroupRequest.GET_ALL (block for all
>> replies, minus the suspected ones) or GroupRequest.GET_NONE (wait for no
>> replies), which is essentially asynchronous.
>>
>
> Ok, that's interesting.
>
> Are there any performance implications of doing async sending this way
> as opposed to a straightforward send() ?

Yes:
- MessageDispatcher has to be prepared to match responses to requests, 
that's some overhead
- You want to install a Marshaller if you expect return values, 
otherwise we use simple&slow Java serialization
- Since you pass org.jgroups.Messages around, you want to 
marshal/unmarshal the buffer inside of those messages yourself, 
otherwise we again use Java serialization

> The use case I'm thinking of here is casting of unreliable messages to
> distributed topic peers in JBM, so we can expect a lot of traffic.

I would not use the MessageDispatcher here,  because you don't need 
correlation, simple Channel.send() will do I think

-- 
Bela Ban
Lead JGroups / Manager JBoss Clustering Group
JBoss - a division of Red Hat

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