10.1 Overview of Data Controls and Declarative Bindings

The Oracle ADF Model layer is a declarative data binding facility. It implements the two concepts in the JSR-227 specification that enable decoupling the user interface technology from the business service implementation: data controls and declarative bindings. Data controls and declarative bindings enable a unified design time and runtime approach to bind any user interface to any backend business service without code.

10.1.1 Data Controls Abstract the Implementation Technology of a Business Service

Data controls abstract the implementation technology of a business service by using standard metadata interfaces to describe the service's operations and data collections. This includes information about the properties, methods, and types involved. At design time, visual tools like JDeveloper can leverage the standard service metadata to simplify binding UI components any data control operation or data collection. At runtime, the generic Oracle ADF Model layer reads the information describing your data controls and bindings from appropriate XML files and implements the two-way "wiring" that connects your user interface to your business service.

10.1.2 Bindings Connect UI Controls to Data Collections and Operations

Declarative bindings abstract the details of accessing data from data collections in a data control and of invoking its operations. There are three basic kinds of declarative binding objects that automate the key aspects of data binding that all enterprise applications require:

• Iterator bindings, which bind to an iterator that tracks the current row in a data collection

• Value bindings, which connect UI components to attributes in a data collection

• Action bindings, which invoke custom or built-it operations on a data control or its data collections

Iterator bindings simplify building user interfaces that allow scrolling and paging through collections of data and drilling-down from summary to detail information. UI components that display data use value bindings. Value bindings range from the most basic variety that works with a simple text field to more sophisticated list, table, and tree bindings that support the additional needs of list, table, and tree UI controls. An action binding is used by UI components like hyperlinks or buttons to invoke methods. An action binding allows the user to click on the component to invoke a business service without code. There are two kinds of action bindings: a regular action binding that invokes a built-in operation, and a method action binding that invokes a custom operation.

Figure 10-1 Bindings Connect UI Components to Data Control Collections and Operations

Note: Value bindings are bindings that have a bound attribute value. All value bindings implement the oracle.binding.AttributeBinding interface. The interface for action bindings is oracle.binding.OperationBinding. Since both of these kinds of binding interfaces are related to UI controls, they both extend the oracle.binding.ControlBinding interface. The term control bindings is used in this guide to describe things that are common to both value bindings and action bindings.