Our application needs this level of locking and we were going to use a
non-persistent entity-bean variable to do this. If your not guaranteed to be
using the same instance for different clients then I'm not sure how to set
up the transactional attributes to use the database locking. The way we'd
like it to work is as follows:
We have an entity bean with CMP. Originally we had get & set methods for the
required data, but after reading this article
http://www.javaworld.com/javaworld/jw-11-1999/jw-11-ejb.html
we decided to go for a single getProperties() method that would return all
persistent attributes in a wrapper object, to reduce the number of network
calls. The locking would exclusively lock the entity bean when this
getProperties() method was called, so that other clients could view old data
on a read-only basis. When the setProperties(Props) was called the lock
would be removed and other clients could then read, lock and update the new
data.
Can this level of locking be done automatically with EJB, or like you said,
would you have to use a boolean isLocked field in the database (which would
be dangerous if the system crashed). Also, if this sort of locking can be
done, would be the same for all major databases - I know some cheapo
databases lock the whole table in certain scenarios.
Regards,
Robert Hargreaves
-----Original Message-----
From: Jim Richards [mailto:[EMAIL PROTECTED]]
Sent: 23 November 1999 01:17
To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
Subject: Re: RMI and EJB problem?
You are not guareenteed to be using the same instance of an object
with entity beans. Why do you want to do this locking anyway? There are
other way of doing this with either the transactional attributes or with
a boolean in the database (so other non-ejb applications can make use of it)
If you really need to do this make the boolean a static variable, this means
there is only one for all instances.
--
Subvert the dominant paradigm
http://www.cyber4.org/members/grumpy/index.html
