What Is Service-Oriented Architecture?
Problem: Several applications would like to use event notification to coordinate their actions, and would like to use messaging to communicate those events. How can messaging be used to transmit events from one service to another? Solutions: Use an event message for reliable, asynchronous event notification between applications. See Figure 5. Figure 5. Event message Interactions: An event message extends the Observer model to a set of distributed applications. Event messages can be sent from one service to another to provide notification of lifecycle events within a service-oriented enterprise, or to announce the status of particular activities. Applications for this pattern include enterprise monitoring and centralized logging. An important characteristic of event messages is that they do not require a reply. An event message can be any kind of message in the messaging system. An event can be an object or data such as an XML document. “If a message says that the Stock price for certai
