Cliser Java ServiceThread Class

Cliser: The Java ServiceThread Class

The Cliser ThreadManager is based upon the Prototype pattern, and so its constructor must be passed an instance of the kind of thread it is to manage. The ServiceThread class provides a superclass from which classes for such threads can be derived. In order for ThreadManager to replicate such threads, the ServiceThread class implements Java's Cloneable interface.

Because it is a subclass of CommunicatorUser and Java does not support multiple inheritance, the ServiceThread class also implements Java's Runnable interface. To do so, it overrides the run() method as follows:

  abstract public void performService();

  public void run()
  {
    for (;;)
    {
      this.performService();
      this.awaitNextJob();
    }
  }

The run() method thus leaves definition of the performService() up to each subclass. The code generator generates a stub for this method, so that completing the definition of performService() is about all that must be done to complete a Cliser-generated Java concurrent (multithreaded) server.

The ServiceThread class provides two synchronization operations:

void awaitNextJob(). As shown above, a subclass of ServiceThread sends itself this message in the run() method whenever it finishes performing its service. The awaitNextJob() message puts the thread to sleep until its ThreadManager (or some other entity) awakens it (see below).
void start(). This same method suffices to either start a ServiceThread that has not been active before, or to awaken a ServiceThread that is sleeping. A non-busy ServiceThread's ThreadManager passes it a Communicator for a given client, and then sends it this message to wake it up.

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This page maintained by Joel Adams (adams@calvin.edu).