1 Introduction to ADF Mobile Client

1.1.1 Understanding Differences Between ADF Mobile Client Applications and ADF Faces Web Applications

The operation of an ADF Mobile client application is substantially different from the operation of an ADF Faces Web application. ADF Faces applications adhere to the standard JSF lifecycle for processing an HTTP request and response. In Web applications, these lifecycle phases help define at various points in the processing of an HTTP request which actions are valid, which values are initialized, and so forth. It is also common for an HTML page to be discarded in the browser, with a completely new page then generated by the server and sent again to the browser (though this is changing with Web 2.0).

In contrast, ADF Mobile client implements an application model where the front end and back end reside on the same device. As it is inefficient to discard the UI every time a page transition occurs, or every time a value is submitted to the database, ADF Mobile client compresses the JSF lifecycle into a dynamic, always-on, event-driven model. This operating model is less like the traditional HTTP request-and-response model, and more like the Web 2.0 model, because a screen is created once and the user interface elements on it are updated dynamically based on the underlying data.

The ADF Mobile client consists of the following three basic layers:

• ADF Business Components: This layer operates very similarly to the ADF Business Components layer in an ADF Faces application. You use the JDeveloper business component design time to create entity objects and view objects, apply view criteria for query customization, and so on. You can also generate Java classes for your entity and view objects and program against a subset of the oracle.jbo package.

• ADF Model (JSR-227): This layer in ADF Mobile client is also very similar to ADF Faces: views are exposed through data controls; action bindings, method bindings, and iterator bindings are all available through the existing JDeveloper design time. However, it is this layer where some differences start to emerge. The current ADF Model layer is designed to support the JSF lifecycle among other things. Since the lifecycle does not exist in ADF Mobile client, some of the lifecycle-oriented constructs do not apply to ADF Mobile client applications.

• UI: This layer of ADF Mobile client applications is new, but it retains a few key concepts from ADF Faces. ADF Mobile client pages are defined by MCX files, which are similar to JSPX files yet greatly simplified and abstracted in order to support cross-platform development. Many of the basic components that are present in ADF Faces, such as the Input Text, Output Text, and Select One Choice are included in the MCX format. In addition, the components are "wired" to the model layer with JSF Expression Language (EL). Understanding how EL expressions transfer data between the model and UI layers is key to understanding the difference between ADF Faces applications and ADF Mobile client applications.

  In an ADF Faces application, the server processes the JSPX file during the render response phase and replaces EL expressions with actual values. This works for ADF Faces because a new page can be generated and sent to the browser each time a value changes. With ADF Mobile client, however, a page is usually created just once. In order to provide data updates to the controls that are populated with EL expressions, EL event sources and sinks are created for every EL expression on a page. Whenever the underlying value of an EL expression changes, any event sinks for that expression will automatically receive the update. The events transfer data from the business component layer to the UI layer when a record iterator moves, and the events transfer data from the UI layer to the business component layer when a user updates a value on a form. For more information and examples, see Section 6.14.4, "EL Events."

1.4.1 Data Synchronization

ADF Mobile client provides local data storage on the mobile device or smartphone by synchronizing a subset of application data down to the device. This frees you from the need to provide the data synchronization code for your application.

The mobile client enables the table-level data synchronization from server to client through the use of Oracle Database Lite Mobile Server.

For more information, see the following:

• Chapter 9, "Synchronizing ADF Mobile Client Data and Transactions"

• Section 9.3, "Initiating Data Synchronization"

1.4.2 Transaction Synchronization

Typically, server-side business logic cannot be duplicated or approximated on the client. To ensure data integrity, ADF Mobile client synchronizes device-side data transactions upstream via ADF Mobile transaction replay service. These transactions are then replayed through the ADF BC (Entity Object) layer of the base ADF application.

Basically, the transaction replay service enables the mobile client applications running on clients to access and execute business logic components on the server or on the base application. It can replay transactions against a variety of back-end services from ADF Business Component (BC) entity object operations, ADF BC view operations, ADF BC application modules operations and even other interfaces such as web services, Java classes and other elements that can be bound using JSR 227.

The transaction replay service is implemented using J2EE technologies and modeled on the Service Oriented Architecture (SOA). It is independent of the type of the disconnected client, synchronization technologies, application server, and database platform.

The transaction replay service infrastructure resides on the server side of the enterprise application and accepts transactions posted from one or more disconnected clients to a transaction replay service-specific database table. The transactions in this table are configured to map with available Java methods, and are subsequently posted (or replayed) to the enterprise application on behalf of the disconnected client. Using the mapped Java methods for transaction replay allows the implementation of complete server-side business logic for remotely collected data. Server-side business logic can include validation, deferred event triggers, and so on.

Disconnected client transactions that can be replayed using the transaction replay service are dependent on the type of application, as well as on your or your administrator's configurations. You can configure the transaction replay service for use with your disconnected solution (see Section 5.8.4, "How to Create a Transaction Replay Type"). Application administrators can monitor the transaction status and performance of the transaction replay service while in use with a disconnected solution.

The following are examples of transactions that can be replayed:

• Creation of a new contact or account object record

• Updates to existing records

1.5.1 Application Architecture

Your ADF Mobile client application will always extend an existing (base) ADF application:

• Your entity objects will be copies of a subset of the entity objects of the base application.

• Your view objects will either be based on entity objects, or they will be represented by static view objects.

For more information, see Section 5.2, "Extending an ADF Application to Mobile Client."

You use a wizard to generate your mobile client application's business components from the base ADF application's business components.

The following is a potential architecture for your ADF Mobile client application:

• A database-bound, mostly disconnected application that consists of several views bound to data in tables stored in a local database on the device. Data is synchronized from a server database to the mobile device or smartphone. This data synchronization is the primary communication mechanism between the server application along with its data sources and the ADF Mobile client application. The application functionality is largely supported without the use of network connectivity.

For more information, see Chapter 5, "Developing the ADF Mobile Client Data Model."

1.5.2 Typical Development Stages

As with most application development, you perform the following activities when building your ADF Mobile client application:

• Gather requirements

• Design

• Develop

• Test

• Deploy

A disconnectable mobile application is generally created as an extension of a server application. Although the mobile application should not mimic the server/desktop application in its presentation, its underlying data schema will mimic the server's data schema because it is a subset of that server schema.

It is assumed that you have a server-side database with an application schema already in place. The steps you take to build your ADF Mobile application will generally occur as follows:

1. Design mobile tasks. Consider the tasks a mobile user will be performing, keeping in mind that handheld usage is different from that of a laptop or desktop machine. How will the mobile application help users get their jobs done? How will the users interact with the device? The more streamlined the application, the more they will use it. Can peripheral input devices be used (barcode scanners or cameras) to simplify processing? Design your mobile client application to be a genuine assistant to the mobile worker, not just a new data collection tool.

2. Design a mobile data schema. The tasks you are bringing to the mobile application will have some server-side data representation, and likely they will have some server validation code as well. Use that information as a starting point for creation of your mobile application. Examine your server schema and identify the subset of tables and columns that will need to be available in the handheld application.

3. Set up your work environment. Install the necessary applications and complete the required setup for development and deployment. For more information, see Chapter 2, "Setting Up the ADF Mobile Client Environment."

4. Create your mobile client application using JDeveloper:

   • Build your mobile client business services (edit entity objects, create mobile views).

   • Develop mobile client task flows.

   • Design and refine the user interface.

   For more information, see Chapter 5, "Developing the ADF Mobile Client Data Model" and Chapter 6, "Creating the ADF Mobile Client User Interface."

5. Deploy the application to a mobile device, smartphone, device emulator, or smartphone simulator:

   • Set up data synchronization.

   • Create database connections.

   • Set up the mobile device, smartphone, or simulator.

   • Synchronize the data.

   • Deploy the client runtime.

   • Deploy the mobile application.

   Note:

   With ADF Mobile client, it is required that you deploy to the mobile device, smartphone, device emulator, or smartphone simulator before doing any testing and debugging. A mobile client application cannot be run until you deploy it.

   For more information, see Chapter 8, "Deploying ADF Mobile Client Components."

6. Test and debug the application:

   • Test synchronization.

   • Test and debug the application.

   • Optimize performance.

   For more information, see Chapter 10, "Testing and Debugging ADF Mobile Client Applications."

7. Deploy the application to users.

   For more information, see the section about ADF Mobile client deployment in Oracle Fusion Middleware Administrator's Guide for Oracle Application Development Framework.

1.5.3 The Lifecycle of a View

Unlike ADF, the mobile client does not represent a lifecycle-driven system: once its view (page) is created, the flow of data from the UI to the model and back is immediate and continuous. In other words, a page is live as long as it is displayed, which makes Expression Language (EL) expressions live as well. For more information on EL, see Section 1.5.7, "Support for Expression Language."

For more information on ADF lifecycle, see "Understanding the Fusion Page Lifecycle" chapter of Oracle Fusion Middleware Fusion Developer's Guide for Oracle Application Development Framework.

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

1.5.4 Supported Devices and the Supported Database

ADF Mobile client supports BlackBerry smartphones and Windows Mobile devices. The supported database for these devices is SQLite (see Section 1.5.4.1, "What You May Need to Know About SQLite").

1.5.5 Supported ADF Components and Attributes

ADF Mobile client supports many ADF components and attributes. Refer to the following information, organized by layer:

• Model layer. See Section 5.1.1, "Support for the Core ADF Business Components."

• Binding layer. See the following:

  • Section 6.15, "Understanding Binding Layer Components"

  • Section 6.3.2.3, "Adding Data Controls to the View"

  • Section 1.5.7, "Support for Expression Language"

• UI layer. See Chapter 6, "Creating the ADF Mobile Client User Interface."

Although ADF Mobile client is compatible with ADF, there is a number of differences in every layer that exist due to the inherent differences between a mobile application and a Web application.

1.5.6 Support for ADF View Objects

As stated in Oracle Fusion Middleware Fusion Developer's Guide for Oracle Application Development Framework, a view object is an Oracle ADF component that encapsulates an SQL query and simplifies working with its results.

View objects can access the database directly for read operations.

ADF Mobile client provides support for ADF view object functionality, with limited support for database field types.

For more information, see the following:

• "Introduction to View Objects" chapter of Oracle Fusion Middleware Fusion Developer's Guide for Oracle Application Development Framework

• Section 5.2.1, "How to Create Subsets of Entity Objects and View Objects"

• Section 5.3.8, "View Accessor Support for Entity Objects and View Objects"

• Section 5.4, "The Entity Object and View Object Extension"

1.5.7 Support for Expression Language

You use the Expression Language (EL) to enable data binding. For an overview of the use of EL with Oracle ADF, see "Using ADF Model in a Fusion Web Application" chapter in Oracle Fusion Middleware Fusion Developer's Guide for Oracle Application Development Framework.

ADF Mobile client supports the use of compound EL expressions. For more information, see Section 6.14, "Understanding EL Support."

ADF objects exist within different scopes, such as the application scope, session scope, page flow scope, and so on (see "About Object Scope Lifecycles" section in Oracle Fusion Middleware Fusion Developer's Guide for Oracle Application Development Framework). ADF Mobile client, however, only supports the application scope. EL expressions defined in the application scope namespace are available for the life of the application. With the mobile client, you can define an application scope on one view of an application, and then reference it on another.

For more information, see the following:

• Section 1.5.3, "The Lifecycle of a View."

• Section 6.14, "Understanding EL Support."