How can I call externalApplication based on Activemq message using JMS

Question

I build 3 Applications,each Application takes more than 20 min for evaluation.I placed 3 files in the following directories

 ProjectcContextPath/WEB-INF/classes/         


        

Answer 1

Based on these requirements

• When data in the database is changed, a message will be posted on a queue.
• Based on the message content you call another service dynamically.
• That service does some computation, but it's result is not intended for an end-user. It takes 20min.

you could implement a stand-alone application which receives messages synchronously like this (pseudo code):

while (true) {
  Message message = queueReceiver.receive();
  TextMessage textmsg = (TextMessage) message;

  if (textmsg.getText().equals("service1")) {
    new Service1().execute();
  } else if (textmsg.getText().equals("service2")) {
    new Service2().execute();
  } else {
    // Show error
  }
  message.acknowledge();
}

This job runs continuously.

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The differences to your proposal

• Using a stand-alone program (with a main method) instead of a servlet. A servlet is not suitable (because it does not run continuously)
• Implement your services as normal Java classes; calling JSPs or servlets for processing is not useful. They are intended to implement the presentation layer

Update

If your services are only reachable over HTTP (this is the case with servlets/JSP), then you could implement these as a web service.