Hmmm...
We've bean counting on caching of the beans.
Not just caching of the the instance in the pool so that a new instance
doesn't have to be created but caching of the state so a database retrieval
doesn't have to be done every time.
I'm very interested in knowing that which EJB Servers support this level of
caching of the beans.
Imre, since you pointed this scenario out, am I to assume Ejipt supports
this ?
Anyone know about Weblogic ?
Thanks,
Sachin.
-----Original Message-----
From: A mailing list for Enterprise JavaBeans development
[mailto:[EMAIL PROTECTED]]On Behalf Of Imre Kifor
Sent: Friday, May 14, 1999 6:40 AM
To: [EMAIL PROTECTED]
Subject: Re: EJBs and the internet
Andreas,
The spec does not require mandatory passivation of bean instances at the end
of transactions.
As a matter of fact, the spec describes three different
commit options. Option A (page 122, EJB 1.1) describes the exact scenario
you are prohibiting. Using CMP or implementing BMP, of course, doesn't have
anything to do with the above.
Imre Kifor
Valto Systems
-----Original Message-----
From: Andreas Vogel <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Friday, May 14, 1999 9:09 AM
Subject: Re: EJBs and the internet
>Robert,
>
>you need to look carefully at the life cycle definition for entity beans.
An entity
>in the pool is not associated with any data. The association happens at the
begin of
>a transaction, that is ejbLoad(), at the end of the transaction the data is
written
>back into persistence storage (ejbStore()), the entity returns to the pool
and looses
>the association with the data. The next client goes through the same cycle.
The
>advantage of the approach is data integrity, the disadvantages is
performance
>overhead. A container may do clever things when CMP is used.
>
>Cheers,
>
>Andreas
>
>Robert Krueger wrote:
>
>> Andreas Vogel wrote:
>>
>> >
>> > Entity beans are specifically targeted towards transactions. Caching is
a value
>> > add of CMP implementation BMP prevents you from caching.
>> >
>>
>> Why would that be? I thought a container could keep entity bean data in
>> memory no matter if CMP or BMP? My understanding was that say client 1
>> requests an entity bean instance with PK x which is not in main memory.
>> It is retrieved from the DBMS (CMP or BMP) and instantiated in main
>> memory. Then client 2 also requests the entity with PK x, which then may
>> still be in main memory. Where is the difference between CMP or BMP
>> here? It may very well be that I'm misunderstanding the spec as I am not
>> an expert. Could you please enlighten my on that point as it seems to be
>> a very important factor in designing an EJB application using entity
>> beans with BMP with acceptable performance.
>>
>> Thanks,
>>
>> Robert
>>
>> --
>> (-) Robert Kr�ger
>> (-) SIGNAL 7 Gesellschaft f�r Informationstechnologie mbH
>> (-) Br�der-Knau�-Str. 79 - 64285 Darmstadt,
>> (-) Tel: 06151 665401, Fax: 06151 665373
>> (-) [EMAIL PROTECTED], www.signal7.de
>>
>>
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>
>--
>"Programming with Enterprise JavaBeans, JTS and OTS" is now available.
Collect all
>three!
>www.wiley.com/compbooks/vogel
>
>
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