Re: Asynchonrous and synchronous messages on same channel

By 'synchronous', we refer to fact that a caller blocks until all 
replies have been received. This is not the same definition you (I 
think) refer to.

Synchronicity can not be provided by a distributed system, that's why 
Virtual Synchrony was invented 
(http://www.jgroups.org/javagroupsnew/docs/presentations/Overview/HTML/img20.htm)
 
by Ken Birman at Cornell.

Odorico Mendizabal wrote:
> Hi,
>
>
>
> probably this e-mail don't contribute with the question, but I have a doubt 
> and this topic motivate me to write here.
>
>
>
> I don't know how is the implementation (approach) to send synchronous 
> messages on JGroups, but this property (synchrony) is not dependable of the 
> environment (physical devices)?
>
>
>
> My feeling is that you cannot implement synchronous channels if the physical 
> channel is not guarantee timing bounds. Then, JGroups implementations in 
> unpredictable networks never could be provide synchronous communication.
>
> Maybe you should need clock synchronization, or some kind of information 
> capable to represent the time notion in the distributed system.
>
>
>
> Well, repeating, I don't know what is guaranteed and what are the 
> assumptions in JGroups implementation of synchronous messages, but I ask if 
> this is not dependable of the network used, for example?
>
>
>
> Thank you,
>
> Odorico Mendizabal
>
>
>
>
>
> ----- Original Message ----- 
> From: "Tim Fox" <tim.fox@xxxxxxxxx>
> To: <javagroups-users@xxxxxxxxxxxxxxxxxxxxx>
> Cc: "Bela Ban" <belaban@xxxxxxxxx>
> Sent: Monday, September 04, 2006 10:39 PM
> Subject: Re: [javagroups-users] Asynchonrous and synchronous messages on 
> same channel
>
>
>   
>> 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() ?
>>
>> 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.
>>
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>>     
>
>
>               
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>
> -------------------------------------------------------------------------
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> Get stuff done quickly with pre-integrated technology to make your job easier
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>   

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


-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642