Oracle ADF Real World Developer's Guide: Mastering essential tips and tricks for building next generation enterprise applications with Oracle ADF with this book and ebook.

Business logic for an application resides in the area between the UI layer and datasource, fulfilling the requests from the client by interacting with the datasource or other third-party services. A well designed application may have multiple layered structures for business service implementation, where each layer plays a unique role by improving the extensibility of the entire architecture. Let us take a quick look at the various layers found in a multilayered business service implementation:

ADF Business Components along with JDeveloper provide a visual and declarative development approach for building business logic for an application. By default, business components are configured by using XML metadata files. At runtime, the ADF framework uses the configurations stored in metadata XML definition files for instantiating appropriate business components. If you want to override the default behavior of the business components offered by the framework or want to add custom business logic, then you can generate Java implementation for the desired business components and add your logic there. To customize the default behavior of business components, you must override the appropriate methods from the default base class.

In this section, we will create a simple ADF model project to get familiarized with the visual aids and tools for building business logic by using ADF Business Components.

To build business services using ADF Business Components, perform the following steps:

Smoke testing of the business model implementation is essential for the success of any application development. The JDeveloper comes with a Graphical User Interface (GUI) based Model Tester to test your business components.

To test the business components, select the application module in the Application Navigator window, right-click on it, and choose Run or Debug. JDeveloper will display the Oracle ADF Model Tester window as shown in the following screenshot:

The ADF Model Tester tool will let you test the data model that has been exposed through an application module. This includes executing view object instances to query the datasource, traversing master-child view object instances linked though view links by modifying the attribute values, committing or rolling back a transaction, and invoking business methods.

A quick walkthrough of the commonly used ADF Model Tester toolbar buttons is as follows:

Buttons	Description
	The navigation buttons displayed in the toolbar...

In the ADF Model Tester window, select the view object instance in the data model tree on the left and execute the same by double-clicking on it. Alternatively you can right-click on the view instance and select the Show option to execute a specific view object instance. The result will be displayed on the data view page on the right-hand side. You can navigate between rows by using the navigation buttons displayed in the toolbar. If you modify the attribute values, that transaction can be saved by using the transaction commit button.

To test master-detail co-ordination between view objects, double-click on the view link instance displayed between the master and child view object instances in the data model tree.

You can generate a Java test client to test the application module and associated data model. The step for generating a Java client is simple and straightforward.

To generate a Java test client class, perform the following steps:

The following code snippet shows a simple test client program to test an application module:

In the previous section, we discussed building a simple ADF model project and learned how to test the business components by using the built-in Model Tester as well as by using the code. You might be wondering now, how do all these things work even without writing down a single line of code? It's time for us to explore the real heroes who do the real jobs behind the scenes.

If you use ADF Business Components for building business logic, you do not really need to worry about the low-level coding, which is otherwise required for querying the database and populating the collection to be used by the client, tracking the modified item, and posting the updates back to the database. In this section, we will learn about the roles and responsibilities of each business component. We will see how they collaborate and work together at runtime to query the datasource and to manage the user transactions.

In this chapter, we discussed the core building blocks of ADF Business Components and how they collaborate and work together at runtime to perform basic CRUD operations on rows from a datasource. In this chapter, you have learned the following:

This chapter is intended to give you an overview of business components. We will take a closer look at each business component item in the coming chapters. The next chapter discusses the entity object and its basic features. More advanced features of entity objects are covered in Chapter 5, Advanced Concepts on Entity Objects and View Objects.