True singleton for whole computer?

Question

How to create a real singleton for a whole computer in Java?

I have a console app written in Java. if application is executed for a second time I want it to know that the main application is already running (and executing jobs). The second execution will just allow the user to query data (jobs). I know I can create a file and write everything to it, but then I will have to also support computer resets, etc.

Is there a better way to do it?

to summarize:

• I start the app. It has jobs and execute them at wanten interval.
• I start app for a second time. I get message that jobs are already running and I can query data from the first app.
• Start app for 3rd time and it works the same as the 2nd time.
• If I stop the first instance and start a new one it works like the first instance.

P.S. I do know this question must have been asked more then once, but google and StackOverflow search give me links only relative to Singleton Design Pattern.

Answer 1

Here is a link that'll do what you want.

This provides an example of code that binds to a socket at startup and then if something is bound at startup then it sends a message

You can use this to communitcate between your processes.