I have a scenario to ask regarding utilizing the EJB Timer Service.
Use case as follows: The system should be able to schedule a task that will poll/ask our subversion repository for files changes using some particular timestamp.
The idea is that whenever the scheduled task is about to run, it will execute command against a particular svn repository. For this particular purpose, I will not call any external process but will use the 'pure' java way of using the SVNKit java library http://svnkit.com/
My only concern is this: Is it a good idea to use the EJB Timer Service to execute task that will call external processes? My way will use a 'pure' java way but in other scenario such as calling a batch file/command line/external executable directly into the timer service logic.
I worry about the effects of server memory use/performance etc.
Is this a good idea?
The other thought that I am thinking is to just create a 'desktop' application in the server using client based technology such as SWT/Swing that will do the polling and then code the logic there but this will mean that I need to manage two applications. The 'desktop' app that will poll and the 'web' user interface that I will create in Glassfish.
I am leaning towards doing everything in the App server of my choice which is glassfish.
I have used EJB Timer before but it only calls against the database without calling any extenral service and it's just that this scenario came up so I raised a question here to gather more thoughts from those who have experienced doing this.
Any thoughts?
In theory, EJBs aren't supposed to depend on external I/O since it interferes with the container/server's management of bean instances, threads, etc.
In practice, this should work if you take precautions. For example:
Keep in mind that EJB 3.0 timers are persistent (vs EJB 3.1 timers, which have the option of being non-persistent), which means:
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