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From Carl Trieloff <cctriel...@redhat.com>
Subject Re: QPID C++ Broker + persistent store
Date Mon, 23 Feb 2009 16:44:14 GMT

yes, for example in c++ there is a sync and async session. The async one 
return after calling and
allows another message to be sent. Errors or handled async. sync session 
blocks on the call.

The sync / flush commands can be used to control this yourself if you want

This type of thing can be done from any client, which client do you care 
about?
Carl.


ffrenchm wrote:
> Ok I understand your answer, but it raise me another question :) Is there a
> way to have a really asynchronous client/server communication when putting
> messages ? I mean the client send a message and then the server ack the
> client without waiting that the message is on the disk ?
>
> Thanks ...
>
>
> Carl Trieloff wrote:
>   
>>     
>>> Well, I do not understand why the synchronous IO mode is no longer
>>> supported. My experiences of queueing tell me that if you want really
>>> safe
>>> message store you need synchronous IO on message PUT. But maybe did I
>>> miss
>>> some new things which make this feature deprecated ?
>>>
>>>   
>>>       
>> This is a great question:
>>
>> The key is that the C++ broker is that it is an async process, so the 
>> broker has all the logic to know when all the async processing on a 
>> message is complete. So even with a async store, the broker will not ack 
>> the client until the message/update is physically written to disk. Given 
>> this there is no advantage to a sync mode. Async is faster in all cases 
>> - and all the exact same message guarantees are provided using  async.
>>
>> The only reason the sync option was there was to enable testing while 
>> the async impl was been hardened.
>>
>> regards
>> Carl.
>>
>>
>>
>>
>>
>>
>> ---------------------------------------------------------------------
>> Apache Qpid - AMQP Messaging Implementation
>> Project:      http://qpid.apache.org
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>>
>>
>>
>>     
>
>   


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