IBM BPM, V8.0.1, All platforms > Authoring services in Integration Designer > Advanced development topics > Adding Java to the application
Understanding the SCA architecture to Java relationship
The environments for the Service Component Architecture (SCA) and Java are different. Understanding the map between them is the key to developing applications that use both environments.
When you work in an SCA environment, you create artifacts that make sense within the context of SCA. Understanding several key SCA artifacts is the beginning of understanding the relationship between the SCA architecture and the Java environment. A business object is one of these important artifacts. A business object represents in the SCA environment a message that is sent from a Java client. A business object is in an XML format and it is similar in Java terms to a data structure. An interface is another key artifact. An interface is the means of getting input and output into the message sent between the environments. Operations in an interface are similar to methods in Java in that they perform actions. A createEmployeeRecord operation could create an employee record if none existed and use an employee business object as the means of adding information about the new employee.
How is data transferred from a Java client to an SCA artifact like a business object? An SCA application is found within a module. Imports and exports are the means of sending and receiving data from applications outside the module. Imports identify services outside of a module such as a Java application that can be called from within the module. Exports allow the SCA module to listen for requests from external services such as Java clients. Bindings specify the means of transforming the data between the environments. Many bindings are available in IBM Integration Designer such as JMS, MQ, HTTP bindings and bindings for EIS systems like SAP.
Mapping a message to an SCA interface will help you understand these key SCA artifacts and how they are related to familiar Java constructs. 
Integrating SCA modules with imports and exports is an article that explains what bindings, imports and exports are, their
relationship to each other and their relationship to external applications.
Creating an import involves using a visual tool in IBM Integration Designer to create one. Once created, an import sends a request from the SCA application to another application outside. There are many bindings available for the import with the product. Create a JMS import to communicate with a JMS client.shows how to create an import with, in this case, a JMS binding that sends requests to a Java client. It also provides details on setting the binding properties necessary to work with the application being called including using a JNDI lookup name.
Creating an export is a similar process to creating an import. The export listens for requests from another application. Like an import, many bindings are available. Create a JMS export to communicate with a JMS client.shows how to create a JMS export to receive requests from a Java client. You are shown how to select the right data transform, often called serializing and deserializing, as the data is moved in and out of an XML format. You are also shown the role of a function selector, which determines what operation on the SCA application to call when the SCA application is called.
Finally, let's examine the flip side: setting up a Java client that can work with the SCA imports and exports you have created. Suppose you created an SCA interface for an SCA component and created a business object to pass data to the SCA component with this interface. If your Java client was using a TextMessage as the type for use in the message it will pass from the Java client to the SCA application, then you would choose a data format transformation like Serialized Java Object (JMS) when you created the binding. These data transformations are selectable from a list when you create your binding. Create a JMS client to receive messages from a JMS import.shows you the Java code you would need to write on the client side. In this case, it is a Message Driven Bean (MDB) that is listening for a request coming from the SCA import.