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From "Michael Gentry" <blackn...@gmail.com>
Subject Re: Optimistic locking
Date Tue, 10 Apr 2007 15:37:02 GMT
In a lot of web applications (JSP, Struts, Tapestry, ...) the session is
usually stored as a cookie in the browser, so opening a new browser window
and re-connecting to the application won't give you a new session and
therefore you'd be connected to the original session (and DataContext -- I'm
assuming you are storing the DC in the session) with the updated values.
Try your test using different concurrent browsers, such as Firefox and
IE/Safari (for example) and see if you get the same results.  I use
optimistic locking on pretty much everything and haven't noticed a problem.
I wrote this a long time ago, too, which may or may not help:

http://cwiki.apache.org/CAY/optimistic-locking-explained.html

I'll be out-of-touch for most of the rest of the day, but if you still have
problems, perhaps someone else on the list can help.

Thanks,

/dev/mrg



On 4/10/07, Marc Gabriel-Willem <marc.gabriel-willem@side-international.com>
wrote:
>
> Hi,
>
>
>
> I have some trouble with the optimistic locking function.
>
> I set the 'optimistic locking' option to an ObjEntity and moreover I set
> an attribute as "used for locking".
>
>
>
> I'm in a web environment.
>
>
>
> When I do some modification in a DataObject, the 'log' displayed by
> Cayenne displays properly the query using the attribute for locking
> check.
>
> But, when a concurrent client modifies the 'same' DataObject, no error
> is detected ... because the new value for the optimistic check is used.
>
>
>
> It is important to note that the DataObject is modified by different
> browser (so different session data context) and by different child data
> context !
>
>
>
> Scenario:
>
>
>
> My original record > attr1=MyAttr1, attr2=10:15:10
>
> My record modified by client #1> attr1=MyAttr2,
> attr2(UseForLock)=10:18:15 [ attrSpecifiedInWhereClause: 10:15:10 ]
>
> My record modified by client #2> attr1=MyAttr3,
> attr2(UseForLock)=10:19:40 [ attrSpecifiedInWhereClause: 10:18:15 ]
>
>
>
> The value of the attribute used for optimistic locking seems to be
> refreshed...
>
>
>
> Thank you,
>
> Marc
>
>

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