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Subject: did i understand synchronized scopes correctly (was: [wsbpel] Issue - R49 - Isolated Scopes)
Hello,
BTW: let me just state some assertions and assumptions to
see if I understand the spec in this area correctly:
- this applies to a single process instance only (since
variables cannot be shared across multiple) -> the term resource is here a
bit missleading, i would really write variable here, resources would apply web
services.
- it syncronizes multiple instances of the same scope as
well as multiple scopes (within the same process instance). Therefore the access
on variables will have to do the lock checking
- deadlocks might be avoided by analysing each scopes
access to variables and by using a single group lock (i.e. all synchronized
scopes which are known to touch variable a must aquire the lock-a before locking
any variable). This analysing is however not possible for dynamic (Xpath)
variable access, right?
Gruss
Bernd
From: Danny van der Rijn [mailto:dannyv@tibco.com] Sent: Wednesday, January 24, 2007 7:02 PM To: wsbpel@lists.oasis-open.org Subject: Re: [wsbpel] Issue - R49 - Isolated Scopes existing: The semantics of isolated scopes ensure that the results would be NO DIFFERENT if all conflicting activities .. were conceptually reordered so that either all such activities within S1 are completed before any in S2 or vice versa. proposed: The semantics of isolated scopes ensure that all conflicting activities (read/write and write/write activities) are not executed in parallel. The order of execution is non-deterministic and thus the result is non-deterministic, too. The difference is only in careful wording in the spec that doesn't come out and say that activities can't execute in parallel, only that the data must be treated as if that were so. It's a subtle difference, but it allows some implementers to do some fancy tricks. ws-bpel issues list editor wrote:
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