What you are asking for is close to impossible. Separate VMs are almost always likely to be completely separate applications and therefore have their own address space and process
There are 2 possibilities I can think of. a) Write you own class loader that does process to process communication, possibly UDP broadcast, which if picked up by all other VM class loaders can check to see if they have loaded the class already. You will definitely have problems with this, as UDP is unreliable, and what happens if the class is loaded at the same time by 2 VMs b) Have your class grab a server port, ( one which is numbered less than < 1024 ). As only one process can have access to a server port, the first class to grab it wins, any other class loaded would get a socket error and then you could terminate you application gracefully. This would not need a Class Loaded writing of much logic keith ------------------------------------------------------------------------- Keith Sterling Jacobs Rimell VP of Engineering Jacobs Rimell Ltd 24 Chiswell St London EC1Y 4TY Tel : +44 207 786 4000 Mob : +44 7771 597 630 Fax : +44 207 786 4004 MSN : [EMAIL PROTECTED] http://www.jacobsrimell.com ------------------------------------------------------------------------- IMPORTANT NOTICE: This email is confidential, may be legally privileged, and is for the intended recipient only. If you are not the intended recipient, please inform the sender and delete the email immediately. WARNING: It is impossible to guarantee the content of this message when it is delivered across the internet, therefore the sender accepts no liability for any claims arising from the information contained. > -----Original Message----- > From: Ramakrishna N [mailto:[EMAIL PROTECTED]] > Sent: 22 May 2002 16:42 > To: [EMAIL PROTECTED] > Subject: Off Topic : ClassLoaders > > Hi, > This is an off topic suggestion that I am seeking but its urgent and so > I > am posting it here. > I want only one Instance of a particular Class to be running across > multiple VMs. I mean if I am executing a class in one of the VMs then If I > say run the same Class in another VM of the same machine it should not > run. > How do I achieve this behaviour ? > Currently we have a configuration xml file where in the Application > registers when it has opened and registers again when it has successfully > closed so that in between if I try to open the application in another VM > the > application first reads the configuration xml and understands that one > istance of the application is running and so it exits. > I would like to achieve it through ClassLoaders. Say custom > ClassLoaders. I am sure there should be a way to achieve this without > doing > any I/O operations like opening a socket when the application starts.. > Any help on this would be of great help. Thanks in advance. > > Thanks & Regards, > kris > > ========================================================================== > = > 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".
