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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: ObjectContext per thread or per app?
Date Thu, 17 Feb 2011 08:35:21 GMT
My current favorite pattern is a single read-only context per app (this gives very good read
performance, especially when combined with LOCAL_CACHE cache strategy), and short-scoped per
user contexts for editing (short scoped can mean different things in different apps I guess,
depending on whether you need to carry over uncommitted state between requests, etc.)

Andrus

On Feb 16, 2011, at 4:17 PM, Michael Gentry wrote:
> Hi Christian,
> 
> You'll typically have at least one context-per-user.  (Not always, but
> typically.)  The patterns we use here are to have a thread-based
> context-per-user and also separate (peer or child) contexts on our
> edit pages.  This lets us isolate the edit changes in a different
> context (and wire the UI directly to the underlying Cayenne object)
> and we are able to throw the context away without polluting the main
> thread-based context when needed (such as when there are validation
> errors and the user cancels instead of fixing them).  This approach
> keeps unexpected modified objects from floating around in our
> thread-based context that might later get committed when we didn't
> want them.
> 
> mrg
> 
> 
> On Wed, Feb 16, 2011 at 5:18 AM, Christian Grobmeier
> <grobmeier@gmail.com> wrote:
>> Thanks Andrey,
>> this helped.
>> Christian
>> 
>> On Wed, Feb 16, 2011 at 10:56 AM, Andrey Razumovsky
>> <razumovsky.andrey@gmail.com> wrote:
>>> Hi Christian,
>>> 
>>> In case of Web application it is incorrect to have one ObjectContext,
>>> because you can't really know which session added certain changes, so
>>> you'll be facing tons of multithreading issues, e.g. one session will
>>> commit other session's partial changes. Common way is to have one
>>> context per session, and for easy access to it having it bound to your
>>> servlet's thread. See
>>> http://cayenne.apache.org/doc30/web-applications.html
>>> 
>>> Hope that helps,
>>> Andrey
>>> 
>>> 2011/2/16 Christian Grobmeier <grobmeier@gmail.com>:
>>>> Hello,
>>>> 
>>>> sorry, a dumb question:
>>>> 
>>>> do I need a ObjectContext per thread or per app?
>>>> 
>>>> In fact I wrote a spring bean (its a singleton) which creates one
>>>> single ObjectContext for all my app. In other terms, multiple threads
>>>> will use it to insert, read, commit etc.
>>>> Since ObjectContext offers the commit method, I am now doubting if
>>>> this was correct. I feel it might be good to have an ObjectContext for
>>>> each thread/user. Or does the ObjectContext know what happened as one
>>>> transaction?
>>>> 
>>>> Can you advise?
>>>> 
>>>> Thanks
>>>> Christian
>>>> 
>>>> --
>>>> http://www.grobmeier.de
>>>> 
>>> 
>>> 
>>> 
>>> --
>>> Andrey
>>> 
>> 
>> 
>> 
>> --
>> http://www.grobmeier.de
>> 
> 


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