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From Patricia Shanahan <p...@acm.org>
Subject Re: Question about JavaSpaces functionality
Date Mon, 31 Jan 2011 06:28:29 GMT
Just that I'm seeing indications that the reads and writes may be 
getting mixed up together, and wanted to be sure I'm debugging the right 
end of the problem.

On 1/30/2011 10:26 PM, Mike McGrady wrote:
> I agree and am not sure why you have doubts?
> Sent from my iPhone
> Michael McGrady
> Principal investigator AF081_028 SBIR
> Chief Architect
> Topia Technology, Inc
> Work 1.253.572.9712
> Cel 1.253.720.3365
> On Jan 30, 2011, at 9:59 PM, Patricia Shanahan<pats@acm.org>  wrote:
>> I wish it had been phrased in the same terms as the JLS. I know the write call completion
happens-before the call to the read method. I think that means the same as "the write returns
before the read commences" but I'm not sure.
>> Patricia
>>> There is this, which I assume you have already seen?
>>> Operation Ordering
>>> Operations on a space are unordered. The only view of operation order can be
a thread's view of the order of the operations it performs. A view of inter-thread order can
be imposed only by cooperating threads that use an application-specific protocol to prevent
two or more operations being in progress at a single time on a single JavaSpaces service.
Such means are outside the purview of this specification.
>>> For example, given two threads T and U, if T performs a write operation and U
performs a read with a template that would match the written entry, the read may not find
the written entry even if the write returns before the read. Only if T and U cooperate to
ensure that the write returns before the read commences would the read be ensured the opportunity
to find the entry written by T (although it still might not do so because of an intervening
take from a third entity).
>>> On Jan 30, 2011, at 7:42 PM, Patricia Shanahan wrote:
>>>> Suppose thread A writes an item to a JavaSpace, thread B attempts to read
it, and A's call to the space's proxy write method happens-before B's call to the space's
proxy read method. There are no transactions involved
>>>> Should the read always succeed?
>>>> In other words, should a happens-before relationship between two actions
in a client imply a corresponding happens-before relationship between the corresponding actions
in the actual space, without depending on transaction semantics?
>>>> This question affects whether I'm working on a bug in outrigger or in one
of its tests.
>>>> Thanks for any information.
>>>> Patricia
>>> Michael McGrady
>>> Chief Architect
>>> Topia Technology, Inc.
>>> Cel 1.253.720.3365
>>> Work 1.253.572.9712 extension 2037
>>> mmcgrady@topiatechnology.com

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