As Ittay wrote, the file access is only an example.
I think we might come to a similar problem. In our case we have a cluster with the same JMS queue on each node (so we can send messages even if some nodes in the cluster are down). At a different division we have one jboss with one remote message driven bean for any queue/node on the cluster (that makes several MDBs that might receive messages concurrently).
Now if we want to serialize these messages we need a session bean with serialization. This is as far as i understand the same problem as Ittay has.
Serialization might be necessary to trigger some external actions via sockets or rmi.
Grtnx, Dietmar
Stephen Davidson wrote:
Hi Ittay.
I think what Alex meant is that in this case, the Entity should have the file contents as its value. This is a trick I have pulled a couple of times.
The other option, why don't you open the file as "Locked", so that some other software application in the OS can't do anything while you are working on this file?
Regards, Steve
Ittay Dror wrote:
On Thu, 2003-07-10 at 11:42, Alexey Loubyansky wrote:
Hello Ittay,
JBoss can lock the entity bean for you. If you use the default container configuration (Standard CMP 2.x EntityBean) and don't mark the methods in the entity bean as read-only, once entity's method is called, the entity is locked and other transactions will wait for lock release. The lock will be released when the tx that put the lock ends.
i know about this, but that is not what i need. i need to lock the operations that *use* the entity, not the operations *of* the entity. in the example i gave, imagine i have a file and i want to add a line with the properties of the enitity. if i read the properties one by one and write them to the file, then there's a chance that some other thread will do the same and the result will be undetermined. basically, i want to know that while i'm reading / changing the properties of the entity no other thread is doing the same.
alex
Thursday, July 10, 2003, 11:01:21 AM, Ittay Dror wrote:
ID> say i have a session bean that does some work that is not ejb related.
ID> for example, it creates a file with some data. the data in the file is
ID> based on the contents of an entity bean. now, i want to synchronize on
ID> the entity bean so that two sessio beans will not write to the file
ID> simultaniously. how can i do that? can i do 'synchronize (entityBean)'?
ID> or do i need to create some map from the entityBean's primary key to an
ID> object for locking on it? or is there another way? (the data file is for
ID> example only, so a solution of locking on the file is not good).
ID> thank you, ID> Ittay
------------------------------------------------------- This SF.Net email sponsored by: Parasoft Error proof Web apps, automate testing & more. Download & eval WebKing and get a free book. www.parasoft.com/bulletproofapps _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
------------------------------------------------------- This SF.Net email sponsored by: Parasoft Error proof Web apps, automate testing & more. Download & eval WebKing and get a free book. www.parasoft.com/bulletproofapps _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
