21 Understanding the Fusion Page Lifecycle(fdg-11.1.1.6)

When a page is submitted and a new page requested, the application invokes both the

ADF Faces page lifecycle, which extends the standard JSF request lifecycle, and the

ADF page lifecycle. 

ADF Faces page lifecycle (extended JSF lifecycle)

The extended JSF lifecycle handles submitting the values on the page, validating component values, navigating pages, displaying components on the resulting page, and saving and restoring state.

The JSF lifecycle phases use a UI component tree to manage the display of the faces components. This tree is a runtime representation of a JSF page: each UI component tag in a page corresponds to a UI component instance in the tree.

The FacesServlet servlet manages the request processing lifecycle in JSF applications. FacesServlet creates an object called FacesContext, which contains the information necessary for request processing, and invokes an object that executes the lifecycle.

For more details about the extended JSF lifecycle, see the "Understanding the JSF and ADF Faces Lifecycles" chapter of the Oracle Fusion Middleware Web User Interface Developer's Guide for Oracle Application Development Framework.

ADF page lifecycle

The ADF page lifecycle handles preparing and updating the data model, validating

the data at the model layer, and executing methods on the business layer.

The ADF page lifecycle uses the binding container to make data available for easy referencing by the page during the current page request.

The combined JSF and ADF page lifecycle is only one sequence within a larger sequence of events that begins when an HTTP request arrives at the application server and continues until the page is returned to the client. This overall sequence of events can be called the web page lifecycle. It follows processing through the model, view, and controller layers as defined by the MVC architecture. The page lifecycle is not a rigidly defined set of events, but is rather a set of events for a typical use case.

Figure 21–1shows a sequence diagram of the lifecycle of a web page request using JSF and Oracle ADF in tandem.

The basic flow of processing a web page request using JSF and Oracle ADF happens as

follows:

1. A web request for http://yourserver/yourapp/faces/some.jsp arrives from the client to the application server.

2. The ADFBindingFilter object looks for the ADF binding context in the HTTP session, and if it is not yet present, initializes it for the first time.

Some of the functions of the ADFBindingFilter include finding the name of the binding context metadata file, and finding and constructing an instance of each data control.

3. The ADFBindingFilter object invokes the beginRequest() method on each data control participating in the request. This method gives the data control a notification at the start of every request so that it can perform any necessary setup.

4. The JSF Lifecycle object, which is responsible for orchestrating the standard processing phases of each request, notifies the ADFPhaseListener class during each phase of the lifecycle, so that it can perform custom processing to coordinate the JSF lifecycle with the ADF Model data binding layer. For more information about the details of the JSF and ADF page lifecycle phases, see Section 21.2, "The JSF and ADF Page Lifecycles." The JSF and ADF Page Lifecycles Understanding the Fusion Page Lifecycle 21-3

5. The ADFPhaseListener object creates an ADF PageLifecycle object to

handle each request and delegates appropriate before and after phase methods to

corresponding methods in the ADF PageLifecycle class. If the appropriate

binding container for the page has never been used before during the user's

session, it is created.

6. The first time an application module data control is referenced during the request, it acquires an instance of the application module from the application module pool.

7. The JSF Lifecycle object forwards control to the page to be rendered.

8. The UI components on the page access value bindings and iterator bindings in the page's binding container and render the formatted output to appear in the browser.

9. The ADFBindingFilter object invokes the endRequest() method on each data control participating in the request. This method gives a data control notification at the end of every request, so that they can perform any necessary resource cleanup.

10. An application module data control uses the endRequest notification to release the instance of the application module back to the application module pool.

11. The user sees the resulting page in the browser.

The ADF page lifecycle also contains phases that are defined simply to notify ADF page lifecycle listeners before and after the corresponding JSF phase is executed (that is, there is no implementation for these phases). These phases allow you to create custom listeners and register them with any phase of both the JSF and ADF page lifecycles, so that you can customize the ADF page lifecycle if needed, both globally or at the page level.