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Message-ID: <7262f25e0804032318p36693e39y83da1e4bbc1e651f@mail.gmail.com>
Date: Thu, 3 Apr 2008 23:18:08 -0700
From: "Patrick Linskey" <plinskey@gmail.com>
To: dev@openjpa.apache.org
Subject: Re: difference between datacache and systemDataCache?
In-Reply-To: 
 <OFFD140EF3.5FE76426-ON88257420.007AD522-88257420.007BBBF7@capgroup.com>
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References: <7262f25e0804031142q461619f3lf376c86e8c55a4f6@mail.gmail.com>
	 <OFFD140EF3.5FE76426-ON88257420.007AD522-88257420.007BBBF7@capgroup.com>

>  So just to be sure -
>  Is OpenJPA going to keep the concept of multiple named cache in place at
>  the StoreManager level at least?
>  Is what you meant only from the perspective of the datacache layer itslef?
>  (I Hope it is ;) ).

Yes.

>  Why does OpenJPA do not have multiple named cache capability in its
>  datacache layer?

Historical reasons, basically. OpenJPA is a subset of Kodo; multiple
named caches was one of the things that was kept out of OpenJPA.

-Patrick

On Thu, Apr 3, 2008 at 3:31 PM,  <Frederic_Bellier@capgroup.com> wrote:
> Patrick - thanks a lot for the answer - it helps a great deal understand
>  the design of openjpa.
>
>  But - please - could clarify one part:
>
>  You said - "OpenJPA has a single DataCache" - this is correct in how the
>  data cache is coded currently. But reading the source code of the
>  StoreManager - I can see that OpenJPA understand the concept of multiple
>  named cache very well. In fact I love the fact that the StoreManager
>  aggregate all changes at the cache level (based on name) before propagating
>  them to the datacache manager (it calls getCache(name)). This is fantastic
>  for me becuase since I am doing a new cache plug in for open jpa I can take
>  the call by the CacheStore and send one call to the cache and do the work
>  for the entire collection for a particular cache - This is a far more
>  efficient approach.
>
>  So just to be sure -
>  Is OpenJPA going to keep the concept of multiple named cache in place at
>  the StoreManager level at least?
>  Is what you meant only from the perspective of the datacache layer itslef?
>  (I Hope it is ;) ).
>  Why does OpenJPA do not have multiple named cache capability in its
>  datacache layer?
>
>  F
>
>
>
>
>              "Patrick Linskey"
>              <plinskey@gmail.c
>              om>                                                        To
>                                        dev@openjpa.apache.org
>                                                                         cc
>              04/03/2008 11:42
>              AM                                                    Subject
>                                        Re: difference between datacache
>                                        and systemDataCache?
>              Please respond to
>              dev@openjpa.apach
>                    e.org
>
>
>
>
>
>
>
>
>
>  >  What is the exact concept behind the system wide datacache?
>  >  Is it just a simplified way to get a proxy to all the caches in case
>  >  someone needs it and does not know which cache exactly they should get?
>  It
>  >  seems to just be fullfiling this role.
>
>  Yep, that's its job. Since OpenJPA has just a single data cache (vs.
>  Kodo's multiple named caches), in OpenJPA this is not a proxy.
>
>  >  Why does the broker gets a reference to the systemDataCache when it is
>  >  created?
>
>  What code in particular are you asking about?
>
>  -Patrick
>
>  On Thu, Apr 3, 2008 at 10:29 AM,  <Frederic_Bellier@capgroup.com> wrote:
>  >
>  >  What is the exact concept behind the system wide datacache?
>  >  Is it just a simplified way to get a proxy to all the caches in case
>  >  someone needs it and does not know which cache exactly they should get?
>  It
>  >  seems to just be fullfiling this role.
>  >
>  >  Why does the broker gets a reference to the systemDataCache when it is
>  >  created?
>  >
>  >  F
>  >
>  >
>
>
>
>  --
>  Patrick Linskey
>  202 669 5907
>
>
>


-- 
Patrick Linskey
202 669 5907