Java Message Service, 2nd Edition

The QBorrower and QLender Application

To illustrate how point-to-point messaging works, we will use a simple decoupled request/reply example where a QBorrower class makes a simple mortgage loan request to a QLender class using point-to-point messaging. The QBorrower class sends the loan request to the QLender class using a LoanRequest queue, and based on certain business rules, the QLender class sends a response back to the QBorrower class using a LoanResponseQ queue indicating whether the loan request was approved or denied. Since the QBorrower is interested in finding out right away whether the loan was approved or not, once the loan request is sent, the QBorrower class will block and wait for a response from the QLender class before proceeding. This simple example models a typical messaging request/reply scenario.

Configuring and Running the Application

Before looking at the code, let’s look at how the application works. As with the Chat application, the QBorrower class and QLender class both include a main() method so they can be run as a standalone Java application. To keep the code vendor-agnostic, both classes need the connection factory name and queue names when starting the application. The QLender class is executed from the command line as follows:

java ch04.p2p.QLender ConnectionFactory RequestQueue

where ConnectionFactory is the name of the queue connection factory defined in your JMS provider and RequestQueue is the name of the queue that the QLender class should be listening ...