I thought I would use a cron-job (linux for the win!). But I had made these nice functions with JPQL that retrieved all the users that had the requirements.
I actually stumbled upon the solution quite quickly but boy did it take some annoyance to get it right.
The answer was ManagedScheduledExecutorService. That's a mouthful.
This is a Java EE7 specification so the servers need to implement it to call them selves EE7 Application servers (the web-profile-only servers doesn't count).
With this you can schedule a task (any POJO that implements Runnable which is Java 101).
You can set it to run once, with fixed intervals or fixed delays or you can implement a Trigger (a interface) that sets of at certain times or conditions.
I went for the intervals and Wildfly. Now with Wildfly you can either use the standard config for ManagedScheduledExecutorService or you can config you own. I choose to config my own because the standard one had several threads (4 I think) and I only needed one.
This was done in the config of the server (standalone.xml/domain.xml).
You can also config the threadfactory there.
<managed-scheduled-executor-service name="removerScheduledExectutorService" jndi-name="java:jboss/ee/concurrency/scheduler/RemoverScheduledExectutorService" hung-task-threshold="50000" core-threads="1" keepalive-time="5000" reject-policy="RETRY_ABORT"/>
With the long jndi It actually shows up in the Wildfly server managment interface,
Problems
So I had two problems:1: My intervals wasn't working at all... For some reason it started 3 threads that ran 3 seconds after each other (I had 15 seconds intervals for testing). And then all 3 threads had 15 second intervals between there own executions. I made it print out the threadId and it was the same for all 3 threads.
So either all threads where doing something weird or I had one thread doing intervals very wrong.
Somehow Netbeans deployment annoyed the server. For when I restarted it without deploying a new version, the services actually kick in right. I also tried to do a classic boolean-switcher from the bean that scheduled the tasks, don't really know if it helped or not. But my intervals was working now.
2: I @Inject my facades to the database (Netbeans Facade-pattern, almost like DAO).
First run worked, but the second run had lost its instance.
So after some masterful reading, googling and swearing I found a soultion, I needed to use the InitailContext and get the @Named bean from there.
yourInstance = InitialContext.doLookup("java:global/YourAPP/YourBean");
And then it was all downhill from there.
I got a lot of experience with Calendar and Date, almost every method in Date is deprecated now, with Calendar as a replacement. So I only use Date as date-instances but for manipulating the date I use Calendar. Go Java 8!
So happy coding! If your having any trouble with a scenario like mine, don't be afraid to ask in the comment-field.
