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From fredrick255 <fuzzyjo...@hotmail.com>
Subject Re: JMS Threading Restriction
Date Fri, 08 Aug 2008 18:39:23 GMT

Is this also the case in CMS (activemq-cpp)?



rajdavies wrote:
> 
> 
> On 14 Jun 2008, at 01:50, Joshua Smith wrote:
> 
>> All-
>>
>> I'm reading a number of references on JMS written some time between  
>> 2001 and
>> now. The challenge that comes with that is knowing which things are  
>> still
>> true today and which things were describing the state of affairs at  
>> that
>> time. I found the following paragraph in the O'reilly Java Message  
>> Service
>> (First Edition) book written in 2001 on p. 32. Can anyone confirm  
>> that this
>> is still an accurate description of JMS?
>>
>>
>> "The Chat application ((which is what they use for their JMS example  
>> in the
>> book)) uses a separate session for the publisher and subscriber,  
>> pubSession
>> and subSession, respectively. This is due to a threading restriction  
>> imposed
>> by JMS. ***According to the JMS specification, a session may not be  
>> operated
>> on my more than one thread at a time.*** In our example, two threads  
>> of
>> control are active: the default main thread of the Chat application  
>> and the
>> thread that invokes the onMessage() handler. The thread that invokes  
>> the
>> onMessage() handler is owned by the JMS provider. Since the  
>> invocation of
>> the onMessage() handler is asynchronous, it could be called while  
>> the main
>> thread is publishing a message in the writeMessage() method. If both  
>> the
>> publisher and subscriber had been created by the same session, the two
>> threads could operate on these methods at the same time; in effect,  
>> they
>> could operate on the same TopicSession - a condition that is  
>> prohibited."
>> (emphasis mine)
>>
>>
>> Thanks,
>> Joshua Smith
> 
> 
> Hi Joshua,
> 
> I used to have a copy of that book somewhere!
> Yep - its still an accurate description of JMS
> 
> 
> 
> 
> cheers,
> 
> Rob
> 
> http://open.iona.com/products/enterprise-activemq
> http://rajdavies.blogspot.com/
> 
> 
> 
> 
> 
> 

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