Đặng An: Message Driven Bean (MDB)

Demo: Alpha is the name of a mail-order company. You are part the team that isdeveloping a solution for automating the processes involved between order logging, invoicing, and the shipment of goods. You have to develop a message-driven bean that acts as an intermediary between the sub-systems that constitute the solution. Each of the subsystems is implemented in the form of entity beans. The first subsystem is where the orders are logged. As soon as the order is registered, a message is sent from the Order subsystem to the message-driven bean. The message-driven bean, in turn calls the other two subsystems, Invoicing and Shipping to proceed with the order. In other words, the message-driven bean that you develop should act as a trigger for the other two subsystems.