Then which one is better pessimistic or optimistic.Then only we can
decide for the application server.
>----------
>From: Rickard �berg[SMTP:[EMAIL PROTECTED]]
>Reply To: A mailing list for Enterprise JavaBeans development
>Sent: Friday, July 04, 1997 2:39 PM
>To: [EMAIL PROTECTED]
>Subject: Re: Transaction isolation level useless at the ejb server
>level?
>
>Nittle Gupta wrote:
>> Yes,I too want the answere to this question from sun people.
>> >>If two client requests arrive to the same entity
>> >>object (i.e. same primary key),
>> >>the EJB container can do one of the following:
>> >>
>> >> - use a different bean class instance for each
>> >>transaction context, or
>> >>
>> >> - use a single instance but serialize the use of
>> >>the instance by the transactions
>> >>
>> >>If the first method is used, the underlying resource
>> >>managers will properly
>> >>isolate the work of the multiple clients.
>> >
>> >
>> >I am a bit puzzled by this answer. In the situation
>> >posited above, if two copies of an entity class are
>> >used (one per transaction), and each transaction
>> >modifies its copy, which copy is valid, which is
>> >stored?
>
>This depends on the locking mechanism of the database, and which
>transaction isolation level is set. It is my understanding that if
>optimistic locking is used and two concurrent transactions use the same
>rows in a read/write scenario, the one to commit last will rollback
>(due
>to the data changes by the first transaction). The transaction will in
>this case have to be re-done in order to commit properly.
>
>AFAIK
>
>/Rickard
>
>--
>Rickard �berg
>
>@home: +46 13 177937
>Email: [EMAIL PROTECTED]
>Homepage: http://www-und.ida.liu.se/~ricob684
>
>========================================================================
>===
>To unsubscribe, send email to [EMAIL PROTECTED] and include in the
>body
>of the message "signoff EJB-INTEREST". For general help, send email to
>[EMAIL PROTECTED] and include in the body of the message "help".
>
===========================================================================
To unsubscribe, send email to [EMAIL PROTECTED] and include in the body
of the message "signoff EJB-INTEREST". For general help, send email to
[EMAIL PROTECTED] and include in the body of the message "help".
