Pankaj Tandon wrote:
> Since no one replied so far, I'll take a stab at it... :-)
> If a session bean(stateless) invokes the find on the entityBean
> AND if the following are set in the DepDesc of the session bean:
> isolationLevel TRANSACTION_SERIALIZABLE
> transactionAttribute TX_REQUIRED
> then that instance of the eBean shd be 'locked' till such time this session
> bean is done.
> So to simulate a lock, you can
> - Make the first session bean do a myEBean.setDesc("Foo") ;
> - Put this sessio bean to sleep for a while
> - Attempt to retrive the same eBean thru a seperate client invoked session
> (thru a find on same PK) bean while the
> first client session is asleep.
> - set a diff desc as diffInstanceOfMyEBean.setDesc("Bar")
>
> At the end of both txns the desc shd be set to "Bar".
>
> At least in theory that shd work! I haven't tried it... :-(
>
> Pankaj
>
> Srinivas Hasti <[EMAIL PROTECTED]> on 11/05/99 10:52:11 AM
>
> Please respond to A mailing list for Enterprise JavaBeans development
> <[EMAIL PROTECTED]>
>
> To: [EMAIL PROTECTED]
> cc: (bcc: pankaj tandon/MIS/genco/US)
> Subject: Suggestions
>
> Hi,
> I need to design/develop a entity bean which needs
> to do following
> When a client access the ejb using finder method, if
> find is successful, i need to lock the row in
> database. Second client(doing find with same
> primarykey) should wait till first client is done
> before he can start modifying the row.
>
> Any hints/suggestions are helpful.
>
> Thanks
> H
>
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Yes, exactly. That is the whole point of
isolationLevel TRANSACTION_SERIALIZABLE
transactionAttribute TX_REQUIRED
We do it all the time.
The other alternative is using READ_COMMITTED and select <whatever> for update
(In fact, to digress into vendor specific stuff here, if you're using an ejb
server (in my case weblogic) with oracle, you better do this instead. There is
a bug in oracle that results in failure under heavy load otherwise.)
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