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Re: Issue: Synch/Asynch Web services

From: Doug Bunting <Doug.Bunting@Sun.COM>
Date: Tue, 12 Aug 2003 13:43:25 -0700
To: "Cutler, Roger (RogerCutler)" <RogerCutler@ChevronTexaco.com>
Cc: Geoff Arnold <Geoff.Arnold@Sun.COM>, www-ws-arch@w3.org
Message-id: <3F39516D.4060005@Sun.com>

Thanks Roger,

The proposed definition is not incorrect but answers a different 
question than you are asking or that you believe the "world at large" is 
asking.  It states the classic request / response interaction is a 
synchronous MEP but says nothing about agents implementing such an MEP. 
  In this particular case, the binding to a particular protocol could 
result in either synchronous or asynchronous agents.  As Geoff said 
earlier, this is a property of the binding and not just of the MEP in 
question.  (Not sure we would label the binding as synchronous or 
asynchronous...)

It remains important to note that synchronous MEPs are possible over 
protocols without direct correlation features.  Are you really trying to 
identify those service implementations that *require* correlation 
features independent of the underlying protocol in use, the instances of 
synchronous MEPs bound using asynchronous agents?

thanx again,
	doug

On 12-Aug-03 11:44, Cutler, Roger (RogerCutler) wrote:
> It is really important that WSA nails down definitions for
>     "synchronous" and "asynchronous", because this will
>     allow me to have confidence that Web services will support, in an
> interoperable way, synchronous and asynchronous implementations
> (particulartly the latter, since this is where the problems are most
> likely to arise, is the most different from the historical starting
> point of Web services, and is the most typical of core business
> processes) in applying Web services to
>     business applications. If they don't do so, I won't be able to use
> them at all for core business processes -
>     or I'll have to trust to luck that they will work or be
> intereperable instead.  If I cared a lot about late binding, I would
> also not be able to implement late bound business processes that are
> sensitive to whether the WS will support synchronous or asynchronous
> operations.   Nailing down the definitions will not, in itself, enable
> these desirable outcomes, but is a necessary pre-condition for
> addressing the real issues, which I tried to sketch in section 4 of
> http://lists.w3.org/Archives/Public/www-ws-arch/2003Aug/0001.html.
> 
> To respond to another implied question, it really doesn't matter if an
> approach is formally verifiable if it is incorrect.  It looks to me like
> this one is incorrect -- it says that an MEP that is agreed by
> (virtually) all to be asynchronous is synchronous.  Since the MEP in
> question is very commonly used in practical situations, I'd consider
> that to be a considerable drawback. 
> 
> 
> -----Original Message-----
> From: Geoff Arnold [mailto:Geoff.Arnold@Sun.COM] 
> Sent: Tuesday, August 12, 2003 12:52 PM
> To: Cutler, Roger (RogerCutler)
> Cc: www-ws-arch@w3.org
> Subject: Re: Issue: Synch/Asynch Web services
> 
> 
> 
>>Also -- I do not agree that sync/async is only an implementation 
>>issue. I think it is pretty clear that certain Web services, by their 
>>nature, can be used sync but not async -- or async but not sync -- or 
>>in both ways.  That means to me that it is not an implementation 
>>issue.
> 
> 
> Can we replace the notion of being "used" sync or async with something a
> little more precise? What would be observably different? And "in both
> ways"...?!
> 
> 
>>It also happens to be an issue that is really important to people who 
>>are interested in business applications of Web services.  These 
>>persistent attempts to declare the concepts either to be meaningless 
>>or out of scope are very discouraging.
>>
> 
> Hmmmmm........ I'm surprised that you would characterize a formally
> verifiable approach grounded in message exchange patterns as either
> meaningless or out of scope. But you just said something much more
> interesting to me: "It also happens to be an issue that is really
> important to people who are interested in business applications of Web
> services." Presumably this means that you (or others) are able to
> complete the following paragraph:
>     It is really important that WSA nails down definitions for
>     "synchronous" and "asynchronous", because this will
>     allow me to ______________ in applying Web services to
>     business applications. If they don't do so, I won't be able to -
>     or I'll have to ___________ instead.
> 
> Curious,
> 
> Geoff
> 
> 
> 
> 
Received on Tuesday, 12 August 2003 16:42:55 GMT

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