Processing the Data

When a message is sent from an application (such as the invoice from an order entry system), Mule picks up the message, sends it to a service that processes it using some specific business logic (such as checking the customer and inventory databases), and then routes it to the correct application (such as the order fulfillment system). Mule contains many individual parts that handle the processing and routing of the message. The key part of the service is the service component. The service component executes business logic on messages, such as reading the invoice object, adding information to it from the customer database, and then forwarding it to the order fulfillment application.

An important feature of the service component is that it doesn't have to have any Mule-specific code; it can simply be a POJO, Spring bean, Java bean, or web service containing the business logic for processing data in a specific way. Mule manages the service component, bundles it with configuration settings and exposes it as a service, and ensures that the right information is passed to and from it based on the settings you specified for the service in the Mule configuration file.

You can have many different service components that perform different business logic, such as one that verifies whether the items on the invoice are in stock and one that updates a separate customer database with the order history. The invoice, which is encapsulated in a message, can flow from one service component to the next until all the required processing is complete.

The next section, Routing Messages Between Service Components, describes how Mule routes the messages.