This chapter illustrates the following concepts illustrated in Figure 13-1, and more:

• You expose instances of view objects in an application module to define its data model.

• You write service methods to encapsulate task-level business logic.

• You expose selected methods on the client interface for UI clients to call.

• You expose selected methods on the service interface for programmatic use in application integration scenarios.

  Note that starting in release 12c, support for EJB Session Bean-enabled application modules in an ADF Business Components model project has been deprecated in Oracle JDeveloper. It is no longer possible to create or run EJB Session Bean-enabled application modules in JDeveloper. As an alternative for existing EJB Session Bean-enabled application modules, you may want to migrate application modules services to Web Service-enabled application modules, as described in Creating SOAP Web Services with Application Modules. This approach is consistent with the best practice for exposing service methods using external services.

• You use the application module instance from a pool during a logical transaction that can span multiple web pages or views.

• Your application module works with a Transaction object that acquires a database connection and coordinates saving or rolling back changes made to entity objects.

• The related Session object provides runtime information about the current application user.

Figure 13-1 Application Module Is a Business Service Component Encapsulating a Unit of Work

Description of "Figure 13-1 Application Module Is a Business Service Component Encapsulating a Unit of Work"

You may find it helpful to understand other Oracle ADF features before you start working with application modules. Following are links to other functionality that may be of interest.

• For details about creating shared application modules, see Sharing Application Module View Instances.

• For details about exposing ADF Business Components service methods using external services, see Creating SOAP Web Services with Application Modules.

• For details about how the Data Controls panel exposes the application module to UI developers, see Using ADF Model in a Fusion Web Application.

• For details about configuring application module instances to improve runtime performance, see Using State Management in a Fusion Web Application and Tuning Application Module Pools.

• For details about how to maximize the performance and scalability in the production environment, see the "Tuning Oracle Application Development Framework (ADF)" chapter in Tuning Performance.

• For a quick reference to the most common code that you will typically write, use, and override in your custom application module classes, see Most Commonly Used ADF Business Components Methods.

• For API documentation related to the oracle.jbo package, see the following Javadoc reference document:

  • Java API Reference for Oracle ADF Model

1. In the Applications window, right-click the project in which you want to create the application module and choose New and Application Module.
2. In the Create Application Module wizard, on the Name page, provide a package name and an application module name. Click Next.

   Note:

   In Fusion web applications, the reserved words data, bindings, security, and adfContext must not be used to name your application module. Also, avoid using the "_" (underscore) at the beginning of the name. For more information, see How to Edit an Existing Application Module.

3. On the Data Model page, include instances of the view objects you have previously defined and edit the view object instance names to be exactly what you want clients to see in the Data Controls panel. Then click Next.
4. On the Java page, you can optionally generate the Java files that allow you to programmatically customize the behavior of the application module or to expose methods on the application module's client interface that can be called by clients. To generate an XML-only application module component, leave the fields unselected and click Finish.

   Initially, you may want to generate only the application module XML definition component. After you complete the wizard, you can subsequently use the overview editor to generate the application module class files when you require programmatic access. For details about the programmatic use of the application module, see Customizing an Application Module with Service Methods.

When you create an application module, JDeveloper creates the XML document file that represents its declarative settings and saves it in the directory that corresponds to the name of its package. For example, in the Summit ADF sample application the application module named BackOfficeAppModule in the summit.model package has the XML file ./summit/model/BackOfficeAppModule.xml under the project's source path. This XML file contains the information needed at runtime to re-create the view object instances in the application module's data model.

If you are curious to view its contents, you can see the XML file for the application module by double-clicking the application module node in the Applications window to open the overview editor. In the editor window, click the Source tab to view the XML so that you can inspect it. The Structure window shows the structure of the XML file.

When you create business components, JDeveloper automatically creates a data control that contains all the functionality of the application module. Data controls are an ADF Model abstraction layer that provides supplemental metadata to describe the application module's operations and data collections (row sets of view object instances), including information about the attributes, methods, and types involved. Developers can then use the representation of the data control displayed in JDeveloper's Data Controls panel to create UI components that are automatically bound to the application module. At runtime, the ADF Model layer reads the metadata describing the data controls and bindings from appropriate XML files and implements the two-way connection between the user interface and the business service.

For example, the BackOfficeAppModule application module implements the business service layer of the SummitADF application workspace. Its data model contains numerous view object instances, including several master-detail hierarchies. The view layer of the core Summit ADF sample application consists of JSF pages whose UI components are bound to data from the view object instances in the BackOfficeAppModule's data model, and to built-in operations and service methods on its client interface. For details about how the Data Controls panel exposes the application module to UI developers, see Exposing Application Modules with ADF Data Controls.

You can add a view object instance to an application module as you create the application module with the Create Application Module wizard, or you can add it later to an already created application module.

For information about using the Create Application Module wizard, see How to Create an Application Module.

You add instances of view object components to define the data model of an application module. Figure 13-11 shows a JDeveloper business components diagram of a BackOfficeAppModule application module that appears in the SummitADF workspace of the Summit sample application.

Figure 13-11 Application Module Containing Two Instances of a View Object Component

Description of "Figure 13-11 Application Module Containing Two Instances of a View Object Component"

The sample application module contains two instances of the CustomerVO view object component, with member names of Customer and AnotherCustomer to distinguish them. At runtime, both instances share the same CustomerVO view object component definition—this ensures that they have the same attribute structure and view object behavior—however, each might be used independently to retrieve data about different users. For example, some of the runtime properties, like an additional filtering WHERE clause or the value of a bind variable, might be different on the two distinct instances.

The following example shows how the BackOfficeAppModule application module defines its member view object instances in its XML document file.

<AppModule
   Name="BackOfficeAppModule"
   ...>
   <ViewUsage
      Name="Customer"
      ViewObjectName="oracle.summit.model.appmodule.CustomerVO"/>
   <ViewUsage
      Name="AnotherCustomer"
      ViewObjectName="oracle.summit.model.appmodule.CustomerVO"/>
</AppModule>

After you've created a new application module, you can edit any of its settings by using the Edit Application Module dialog. To launch the editor, in the Applications window, right-click the application module node and choose Open, or double-click the application module. By visiting the different pages of the editor, you can adjust the data model to determine whether or not to reference nested application modules, specify Java generation settings, client interface methods, runtime instantiation behavior, and custom properties.

If you edit the name of your application module, choose a name that is not among the reserved words that Oracle Application Development Framework (Oracle ADF) defines. In particular, reserved words are not valid for a data control usage name which JDeveloper automatically assigns based on your application module's name. In Fusion web applications, these reserved words consist of data, bindings, security, and adfContext. For example, you should not name an application module data. If JDeveloper creates a data control usage with an ID that collides with a reserved word, your application may not reliably access your data control objects at runtime and may fail with a runtime ClassCastException.

Do not name the application module with an initial underscore (_) character to prevent a potential name collision with a wider list of reserved words that begin with the underscore.

Application module names that incorporate a reserved word into their name (or that change the case of the reserved word) will not conflict. For example, Product_Data, Product_data, or just Data are all valid application module names since the whole name does not match the reserved word data.

1. In the Applications window, double-click the application module for which you want to edit the data control name.
2. In the Properties window, expand the Other section, and enter your preferred data control name in the Data Control Name field.

A common question related to application modules is, "How big should my application module be?" In other words, "Should I build one big application module to contain the entire data model for my enterprise application, or many smaller application modules that allow me to compartmentalize the application according to functionality?" The answer depends on your situation.

In general, application modules should be as big as necessary to support the specific use case you have in mind for them to accomplish. They can be assembled from finer-grained application module components using a nesting feature, as described in Defining Nested Application Modules. Since a complex business application is not really a single use case, a complex business application implemented using Oracle ADF will typically not be just a single application module.

In actual practice, you may choose any granularity you wish to support the type of modularization you require. For example, the need to support disparate data sources or the need to configure separate tuning options are both legitimate cases for creating multiple application modules. Or, in a small application with one main use case and a "backend" supporting use case, you might create two application modules. However, for the sake of simplicity you can combine both use cases, rather than create a second application module that contains just a couple of view objects.

Other situations may dictate creating more than one root application module. For example, if you need to support more than one transaction per user session, you can create multiple application modules. Alternatively, you can work with data control scope and task flows to manage transactions, as described in Managing Transactions in Task Flows.

While designing an application module, you use instances of a view object component to define its data model. Just as the user interface may contain two instances of a Button component with member names of myButton and anotherButton to distinguish them, your application module contains two instances of the CustomerVO view object component, with member names of CustomerList and AnotherCustomerList to distinguish them.

The type of connection all default application module configurations use is a JDBC data source. You define a JDBC data source as part of your application server configuration information, and then the application module looks up the resource at runtime using a logical name. When you use the JDBC data source as the connection type, your application resource connection details may change, and you will not need to change the deployed application module configuration. For this reason the JDBC data source is the recommended choice for all application module configurations. Figure 13-12 shows how the default selection appears in the overview editor for application module configurations (on the bc4j.xcfg file). To display the application module configuration overview editor, double-click the application module in the Applications window and, in the overview editor, select the Configurations navigation tab. Then, in the Configurations page of the overview editor, click the configuration hyperlink.

Figure 13-12 JDBC DataSource Connection Type Setting

Description of "Figure 13-12 JDBC DataSource Connection Type Setting"

The following example shows the <resource-ref> tags in the web.xml file of a Fusion web application. These define two logical data sources named jdbc/Summit_adfDS and jdbc/Summit_adfCoreDS. The application module configurations overview editor references this logical connection name after the prefix java:comp/env in the Datasource Name field. For example, the JDBC data source name for the same Fusion web application would display the value java:comp/env/jdbc/summit_adfDS that you can select. Therefore the Datasource Name field is prepopulated with the JNDI name for all available application resources connection names.

  <!-- In web.xml -->
  <resource-ref>
    <res-ref-name>jdbc/summit_adfDS</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
  </resource-ref>
  <resource-ref>
    <res-ref-name>jdbc/summit_adfCoreDS</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
  </resource-ref>

You can directly edit the Datasource Name field when you want to specify a connection name for a global data source that is required to run the application on a target standalone application server. When you deploy to Oracle WebLogic Server, by default, the application-specific data source is not packaged with the application and Oracle WebLogic Server is configured to find a global data source named jdbc/applicationConnectNameDS using the look up java:comp/env/jdbc/applicationConnectNameDS. Therefore, by following this naming convention, you enable a single data source connection name to work correctly when running the application in JDeveloper using an application-specific data source or when running on the deployed standalone server using a global data source.

When you select connection type in the Edit Configuration dialog, JDeveloper updates the application module configuration file, bc4j.xcfg in the ./common subdirectory relative to the application module's XML document. The file defines configurations for all of the application modules in a single Java package. The bc4j.xcfg file does not appear in the Applications window. To view the bc4j.xcfg file in JDeveloper, double-click the application module in the Applications window and, in the overview editor, select the Configurations navigation tab. Then, in the Configurations page of the overview editor, click the configuration hyperlink.

For example, if you open the overview editor for application module configurations (on the bc4j.xcfg file) for the SummitAppModule application module in the ./classes/oracle/summit/model/services/common directory of the core Summit ADF sample application's Model project, you will see the named configurations for this application module.

The configurations defined by the bc4j.xcfg file allow the Fusion web application to interact with specific, deployed application modules. In addition to the connection type for the application module, the bc4j.xcfg file contains metadata information about application module names and it contains the runtime parameters that are configured for the application module. The application resource database connection details for the named connection type are defined in the Connections node of the Applications window and saved in the application's connections.xml file.

The following example displays a sample bc4j.xcfg file from the core Summit ADF sample application. The configurations SummitAppModuleLocal and SummitAppModule both reference a data source (named Summit_adfDS) in the JDBCDataSource attribute. The JDBCDataSource attribute in each configuration specifies the JNDI name for the application resources connection name in the form of java:comp/env/jdbc/applicationConnectNameDS, where applicationConnectName is the name of the application resources database connection defined in JDeveloper (in this case, Summit_adf). This JNDI naming convention (with the application-specific name space java:comp/env/jdbc/ and DS appended to the application resources database connection name ) ensures that a deployed Fusion web application will run on Oracle WebLogic Server using the application's global data source and no changes will be required. The global data source is typically defined by the application server administrator using the Oracle WebLogic Server Administration Console.

<BC4JConfig version="11.1" xmlns="http://xmlns.oracle.com/bc4j/configuration">
   <AppModuleConfigBag ApplicationName="oracle.summit.model.services.SummitAppModule">
      <AppModuleConfig name="SummitAppModuleLocal"
                       DeployPlatform="LOCAL"
                       JDBCName="summit_adf"
                       jbo.project="oracle.summit.model.Model"
                       java.naming.factory.initial="oracle.jbo.common.JboInitialContextFactory"
                       ApplicationName="oracle.summit.model.services.SummitAppModule">
         <Database jbo.TypeMapEntries="Java"/>
         <Security AppModuleJndiName="oracle.summit.model.services.SummitAppModule"/>
         <Custom ns0:JDBCDataSource="java:comp/env/jdbc/summit_adfDS"
                                     xmlns:ns0="http://xmlns.oracle.com/bc4j/configuration"/>
      </AppModuleConfig>
      ...
   </AppModuleConfigBag>
</BC4JConfig>

1. In the Applications window, double-click the application module for which you want to edit the configuration.
2. In the overview editor, click the Configurations navigation tab.
3. In the Configurations page, click the configuration hyperlink that you want to edit.

   The Configuration page may display these three default configurations:

   • appModuleNameLocal: One local configuration is automatically defined when you create the application module. Create a new local configuration, for example, when you want to change the runtime properties for the application module for testing purposes.

   • appModuleNameShared: The shared application module configuration is present only when a named instance of a shared application module has been defined in the Project Properties dialog for the data model project. A shared application module is one that groups view instances when you want to reuse lists of static data across the application. For example, you can define a shared application module to group view instances that access lookup data, such as a list of countries.

   • appModuleNameService (type SI for service interface): The service interface configuration is present only when the service interface (web service implementation wrapper) has been defined in the Service Interface page of the overview editor for the application module. An application module exposed as a web service allows your application module to participate in a composite application to provide data access and method calls to web service clients. The same application module can support interactive web user interfaces using ADF data controls and web service clients.

4. In the overview editor for application module configurations (on the bc4j.xcfg file), click the Database and Scalability tab to customize the desired runtime properties and save the changes.

1. In the Applications window, right-click the project that contains the application module and choose Project Properties.
2. In the Project Properties dialog, select ADF Business Components and from the Connection dropdown list, choose the desired connection and then click the Edit icon.
3. In the Edit Database Connection dialog, make the appropriate changes.
4. Click OK.

1. In the Applications window, double-click the root application module for which you want to define a nested application module.
2. In overview editor, click the Data Model navigation tab.
3. In the Data Model Components page, expand the Application Module Instances section and, in the Available list, select the application module that you want to add to the data model.

   The New App Module Instance field below the list shows the name that will be used to identify the nested application module that you add to the data model.

4. To change the name before adding it, type a different name in the New App Module Instance field.
5. With the desired application module selected, shuttle the application module to the Selected list.

   For example, in the SummitADF workspace of the Summit ADF sample application, the SummitAppModule application module defines two nested application module instances: BackOfficeAM and CustomerSelfServiceAM. Figure 13-14 shows the application module instances BackOfficeAM and CustomerSelfServiceAM have been added to the Selected list.

   Figure 13-14 Data Model Displays Added Application Module Instances

   

At runtime, your application works with a main — or what's known as a root — application module. Any application module can be used as a root application module; however, in practice the application modules that are used as root application modules are the ones that map to more complex end-user use cases, assuming you're not just building a straightforward CRUD application. When a root application module contains other nested application modules, they all participate in the root application module's transaction and share the same database connection and a single set of entity caches. This sharing is handled for you automatically by the root application module and its Transaction object.

Additionally, when you construct an application using an ADF bounded task flow, to declaratively manage the transactional boundaries, Oracle ADF will automatically nest application modules used by the task flow at runtime. For details about bounded task flows and transactions, see Managing Transactions in Task Flows.

1. In the Applications window, right-click the data model project in which you want to create the diagram and choose New and then Business Components Diagram.
2. In the Create Business Components dialog, enter a diagram name and a package name in which the diagram will be created.
3. Click OK to create the empty diagram and open the diagrammer.
4. In the Applications window, select the desired application module and drop it onto the diagram surface.
5. Inside the application module diagram, right-click the desired diagram node and choose Visual Properties and make the desired changes in the Edit Visual Properties dialog.
6. In the diagram editor, click anywhere outside of the application module diagram to display the Properties window for the diagram editor and make these changes:

   • Set the layout style

   • Change the font

   • Turn off the grid

After you complete these steps, the diagram looks similar to the diagram shown in Figure 13-15.

Figure 13-15 Partial UML Diagram of Application Module

Description of "Figure 13-15 Partial UML Diagram of Application Module"

When you create a business components diagram, JDeveloper creates a .adfbc_diagram file to represents the diagram in a subdirectory of the project's model path that matches the package name in which the diagram resides.

By default, the Applications window unifies the display of the project content's paths so that ADF components and Java files in the source path appear in the same package tree as the UML model artifacts in the project model path. You can use the Applications Window Options > Directory View toolbar option in the Applications window to switch between the unified directory view and a more distinct directory path view of the project content.

The UML diagram of business components is not just a static picture that reflects the point in time when you dropped the application module onto the diagram. Rather, it is a UML-based rendering of the current component definitions, so it will always reflect the current state of affairs. The UML diagram is both a visualization aid and a visual navigation and editing tool.

You can bring up the overview editor for any application module in a diagram by choosing Properties from the context menu (or by double-clicking the application module).

You can also perform some application module editing tasks directly on the diagram, tasks such as renaming view object instances, dropping view object definitions from the Applications window onto the data model to create a new view object instance, and removing view object instances by pressing the Delete key.

After you display the application module in the diagram, you can use the Edit Visual Properties dialog to control its display options. To display the dialog for the diagram, in the diagram, right-click the application module node and choose Visual Properties.

In the Display page, toggle properties like the following:

• Show Package — to display the package name

• Show Methods — to display service methods

• Show Stereotype — to display the type of object (for example "<<application module>>")

• Show Usages — to display all usages by other application modules in the current project

In the Methods page, consider changing the following settings depending on the amount of detail you want to provide in the diagram:

• Show Visibility (public, private, etc.)

• Show Return Type of Method

• Show Static Methods

By default, all operations of the application module are fully displayed, as shown by the Edit Visual Properties dialog settings in Figure 13-16.

Figure 13-16 Edit Visual Properties Dialog with Default Diagram Editor Options

Description of "Figure 13-16 Edit Visual Properties Dialog with Default Diagram Editor Options"

On the context menu of the diagram, you can also select to View As:

• Compact — to show only the icon and the name

• Symbolic — to show service operations

• Expanded — to show operations and data model (default)

Initially, if you show the methods for the application module, the diagram displays all the methods. Any method it recognizes as an overridden framework method displays in the <<Framework>> operations category. The rest display in the <<Business>> methods category.

The Exclude Method Filters setting in the Methods page of the Edit Visual Properties dialog is a regular expression that you can use to filter out methods you don't want to display on the diagram. For example, by setting Exclude Method Filters to:

findLoggedInUser.*|retrieveOrder.*|get.*

you can filter out all of the following application module methods:

• findLoggedInUserByEmail

• retrieveOrderById

• All the generated view object getter methods

After selecting the application module on the diagram — or any set of individual view object instances in its data model — you can choose Show > Related Elements from the context menu to display related component definitions on the diagram. In a similar fashion, choosing Show > Implementation Files will include the files that implement the application module on the diagram. You can repeat these options on the additional diagram elements that appear until the diagram includes the level of detail you want to convey.

Figure 13-17 illustrates how the diagram displays the implementation files for an application module. You will see the related elements for the application module's implementation class (AppModuleImpl). The diagram also draws an additional dependency line between the application module and the implementation class. If you have cast the application module instance to a specific custom interface, the diagram will also show that.

Figure 13-17 Adding Detail to a Diagram Using Show Related Elements and Show Implementation Files

1. Run the Oracle ADF Model Tester and double-click a view object instance to query its data.
2. Make a note of the current values of several attributes for a few rows.
3. Update those rows to have a different value for those attributes, but do not commit the changes.
4. Choose File > Save Transaction State from the Oracle ADF Model Tester main menu.

   A Passivated Transaction State dialog appears, indicating a numerical transaction ID number. Make a note of this number.

5. Exit the Oracle ADF Model Tester completely.
6. Restart the Oracle ADF Model Tester and double-click the same view object instance to query its data.
7. Notice that the data is not changed. The queried data from the data reflects the current state of the database without your changes.
8. Choose File > Restore Transaction State from the Oracle ADF Model Tester main menu, and enter the transaction ID you noted in Step 4.

Applications you build that leverage an application module as their business service take advantage of an automatic application module pooling feature. This facility manages a configurable set of application module instances that grows and shrinks as the end-user load on your application changes during the day. Due to the natural "think time" inherent in the end user's interaction with your application user interface, the number of application module instances in the pool can be smaller than the overall number of active users using the system.

As shown in Figure 13-18, as a given end user visits multiple pages in your application to accomplish a logical task, with each page request an application module instance in the pool is acquired automatically from the pool for the lifetime of that one request. At the end of the request, the instance is automatically returned to the pool for use by another user session. In order to protect the end user's work against application server failure, the application module supports the ability to freeze the set of pending changes in its entity caches to a persistent store by saving an XML snapshot describing the change set. For scalability reasons, this state snapshot is typically saved in a state management schema that is a different database schema than the one containing the application data.

Figure 13-18 Using Pooled Application Modules Throughout a Multipage, Logical Unit of Work

Description of "Figure 13-18 Using Pooled Application Modules Throughout a Multipage, Logical Unit of Work"

The pooling algorithm affords a tunable optimization whereby a certain number of application module instances will attempt to stay "sticky" to the last user session that returned them to the pool. The optimization is not a guarantee, but when a user can benefit from the optimization, they continue to work with the same application module instance from the pool as long as system load allows. When load is too high, the pooling algorithm uses any available instance in the pool to service the user's request and the frozen snapshot of their logical unit of work is reconstituted from the persistent store to allow the new instance of the application module to continue where the last one left off. The end user continues to work in this way until they commit or roll back their changes.

Using these facilities, the application module delivers the productivity of a stateful paradigm that can easily handle multipage work flows, in an architecture that delivers the runtime performance near that of a completely stateless application. You will learn more about these application module features in Using State Management in a Fusion Web Application and about how to tune them in Tuning Application Module Pools.

To add a custom service method to your application module, you must first enable a custom Java class for it. If you have configured your IDE-level Business Components Java generation preferences to automatically generate an application module class, a custom class will be present. As Figure 13-19 shows, if you're not sure whether your application module has a custom Java class, open the overview editor for the application module node in the Applications window. The Java Classes page of the editor displays the complete list of classes generated for the application module in the project. If the file exists because someone created it already, then the Java Classes page will display a linked file name identified as the Application Module Class. To open an existing file in the source editor, click the corresponding file name link.

Figure 13-19 Application Module's Custom Java Class in Overview Editor

If no Java class exists in your project, you can generate one using the Java Classes page of the overview editor for the application module.

Before you begin:

It may be helpful to have an understanding of application module service methods. For more information, see Customizing an Application Module with Service Methods.

You may also find it helpful to understand functionality that can be added using other Oracle ADF features. For more information, see Additional Functionality for Application Modules.

You will need to complete this task:

• Create the desired application modules, as described in How to Create an Application Module.

To generate a Java file for your application module class:

1. In the Applications window, double-click the application module.
2. In the overview editor, click the Java navigation tab and then click the Edit java options button.
3. In the Select Java Options dialog, select Generate Application Module Class.
4. Click OK.

   The new .java file will appear in the Java Classes page.

When you generate a custom class for an application module, JDeveloper creates the file in the same directory as the component's XML document file. The default name for its custom Java file will be AppModuleNameImpl.java.

The Java generation option choices you made for the application module persist on the Java Classes page on subsequent visits to the overview editor for the application module. Just as with the XML definition file, JDeveloper keeps the generated code in your custom Java classes up to date with any changes you make in the editor. If later you decide you do not require a custom Java file, from the Java Classes page open the Select Java Options dialog and deselect Generate Application Module Class to remove the custom Java file from the project.

By default, the application module Java class will look similar to what you see in the following example when you've first enabled it. Of interest, it contains Getter methods for each view object instance in the data model.

package oracle.summit.model.services;

import oracle.jbo.server.ApplicationModuleImpl;
// ---------------------------------------------------------------------
// ---    File generated by ADF Business Components Design Time.
// ---    Custom code may be added to this class.
// ---    Warning: Do not modify method signatures of generated methods.
// ---------------------------------------------------------------------
public class AppModuleImpl extends ApplicationModuleImpl {
  /** This is the default constructor (do not remove) */
  public AppModuleImpl() { }

  /** Container's getter for YourViewObjectInstance1 */
  public YourViewObjectImpl getYourViewObjectInstance1() {
    return (YourViewObjectImpl)findViewObject("YourViewObjectInstance1");
  }

  // ... Additional ViewObjectImpl getters for each view object instance

  // ... ViewLink getters for view link instances here
}

As shown in Figure 13-20, your application module class extends the base ADF ApplicationModuleImpl class to inherit all the default behavior before adding your custom code.

Figure 13-20 Your Custom Application Module Class Extends ApplicationModuleImpl

Description of "Figure 13-20 Your Custom Application Module Class Extends ApplicationModuleImpl "

To add a custom service method to an application module, simply navigate to the application module's custom class and enter the Java code for a new method into the application module's Java implementation class. Use the following guidelines to decide on the appropriate visibility for the method:

• If you will use the method only inside this component's implementation as a helper method, make the method private.

• If you want to allow eventual subclasses of your application module to be able to invoke or override the method, make it protected.

• If you need clients to be able to invoke it, it must be public.

The following example shows a private retrieveOrderById() helper method in the AppModuleImpl.java class for the AppModule application module. It uses the static getDefinitionObject() method of the OrdEOImpl entity object class to access its related entity definition, it uses the createPrimaryKey() method on the entity object class to create an appropriate Key object to look up the order, and then it uses the findByPrimaryKey() method on the entity definition to find the entity row in the entity cache. It returns an instance of the strongly typed OrdersImpl class, the custom Java class for the Orders entity object.

// In summit.model.appmodule.service.AppModuleImpl class
/*
 * Helper method to return a Order by Id
 */
private OrdersImpl retrieveOrderById(long orderId) {
  EntityDefImpl orderDef = OrdersImpl.getDefinitionObject();
  Key orderKey = OrdersImpl.createPrimaryKey(new DBSequence(orderId));
  return (OrdersImpl)orderDef.findByPrimaryKey(getDBTransaction(), orderKey);
}

The following example shows a public findOrderAndCustomer() method that allows the caller to pass in an ID of an order to be created. It uses the getCustomer() method of the OrdersImpl entity object class to access its related entity definition.

/*
 * Create a new Customer and Return its new id
 */  
public String findOrderAndCustomer(long orderId) {
    OrdersImpl order = retrieveOrderById(orderId);
  if (order != null) {
        CustomerImpl cust = order.getCustomer();
    if (cust != null) {
      return "Customer: " + cust.getName() + ", Location: " + cust.getCity();
    }
    else {
      return "Unassigned";
    }
  }
  else {
    return null;
  }
}

When you are ready to test the methods of your custom application module, you can use JDeveloper to generate JUnit test cases. With JUnit, you can use any of the programmatic APIs available in the oracle.jbo package to work with the application module and invoke the custom methods. For details about using JUnit with ADF Business Components, see Regression Testing with JUnit.

As an alternative to JUnit test cases, a common technique to test your custom application module methods is to write a simple test case. For example, you could build the testing code into an object and include that code in a static main() method. The following example shows a sample main() method you could add to your custom application module class to test the sample methods you will write. You'll make use of a Configuration object (see How to Create a Command-Line Java Test Client) to instantiate and work with the application module for testing.

A glance through the code in the following example shows that it exercises the methods created in the previous examples to:

1. Retrieve the total for order 101.

2. Retrieve the name of the customer for order 101.

3. Set the status of order 101 to the value "Y".

package oracle.summit.model.appmodule.service;

import oracle.jbo.ApplicationModule;
import oracle.jbo.JboException;
import oracle.jbo.client.Configuration;

public class TestAM {
    public TestAM() {
        super();
    }

    /*
     * Testing method
     */

    public static void main(String[] args) {
      String amDef = "oracle.summit.model.appmodule.service.AppModule";
      String config = "AppModuleLocal";
      ApplicationModule am =
                      Configuration.createRootApplicationModule(amDef,config);
        /* 
         * NOTE: This cast to use the AppModuleImpl class is OK since this
         *       code is inside a business tier file and not in a
         *       client class that is accessing the business tier from "outside".
         */
        AppModuleImpl service = (AppModuleImpl)am;

        String customerName = service.findOrderAndCustomer(101);
        System.out.println("Customer for Order # 101 = " + customerName);
        try {
           service.updateOrderStatus(101,"Y");
        }
        catch (JboException ex) {
           System.out.println("ERROR: "+ex.getMessage());
        }
      Configuration.releaseRootApplicationModule(am,true);
    }
}

Running the custom application module class calls the main() method in the above example and produces the following output:

anonymous
Customer for Order # 101 = Customer: Kam's Sporting Goods, Location: Hong Kong

Any time your application logic accesses a row set to perform programmatic iteration, you should use a secondary row set iterator when working with view object instances in an application module's data model, or view link accessor row sets of these view object instances, since they may be bound to user interface components. To create a secondary iterator, use the createRowSetIterator() method on the row set you are working with. When you are done using it, call the closeRowSetIterator() method on the row set to remove the secondary iterator from memory. The following example shows a typical application module custom method that correctly uses a secondary row set iterator for programmatic iteration, because the CustomerView1 view object instance in its data model may be bound to a user interface (either now or at a later time).

// Custom method in an application module implementation class
public void doSomeCustomProcessing() {
    ViewObject vo = getCustomerView1();
    // create secondary row set iterator with system-assigned name
    RowSetIterator iter = vo.createRowSetIterator(null);
    while (iter.hasNext()) {
        Row r = iter.next();
        // Do something with the current row.
        Integer custId = (Integer)r.getAttribute("Id");
        String name  = (String)r.getAttribute("Name");
        System.out.println(custId + " " + name);
    }
    // close secondary row set iterator
    iter.closeRowSetIterator();
}

There are two important reasons to follow this recommendation. Failing to do so can lead to confusion for the end user when the current row unexpectedly changes or it can introduce subtle business logic errors because the first or last row, or both rows get skipped.

• Confusing the end user by changing the current row unexpectedly

  The iterator bindings determine what row the end-user sees as the current row in the row set. If your own programmatic logic iterates through the row set using the same default row set iterator that the iterator binding uses, you may inadvertently change the current row the user has selected, leaving the user confused.

• Introducing subtle business logic errors by inadvertently skipping the first or last row

  Iterator bindings force their row set iterator to be on a valid row to guarantee that UI components display data when the row set is not empty. This has the side-effect of preventing your custom logic from navigating to the slot either before the first row or to the slot after the last row (when it is using the same row set iterator as an iterator binding). In concrete terms, this means that a typical while (iter.hasNext()) row set iteration loop will either be skipped or start by processing the second row instead of the first as shown in the following example.

// Reset the default row set iterator (iter) to the slot before the first row
iter.reset();
// If an iterator binding is bound to the same default row set iterator,
// then it has already forced it to navigate to the first row here instead
// of being on the slot before the first row.
// 
// If the row set iterator has only one row, the following will then return false
while (iter.hasNext()) {
  // If the row set has more than one row, the first time through the loop
  // this call to next() will return the second row rather than the first
  // row as expected.
  Row curRow = iter.next();
  // Do something with current row
}

1. In the Applications window, double-click the application module for which you want to generate the resource bundle.
2. In the overview editor, click the General navigation tab and enter any display name.

   Adding a display name for the application module will generate the .properties file with a message key for the display name.

3. Save the file.

When you generate a resource bundle for an application module, JDeveloper creates the .properties file in the same directory as the component's XML document file. The default name for its custom Java file will be AppModuleNameMsgBundle.properties.

The following example shows the ResourceBundle element in the application module XML document that references the .properties file.

<AppModule
  ...
  <ResourceBundle>
    <PropertiesBundle
      PropertiesFile=
         "oracle.summit.model.services.common.BackOfficeAppModuleMsgBundle"/>
  </ResourceBundle>
</AppModule>

1. In the Applications window, double-click the application module for which you want to define the client interface.
2. In the overview editor, click the Java navigation tab and in the Client Interface section, click the Edit application module client interface button.
3. In the Edit Client Interface dialog, select one or more desired methods from the Available list and click the Add button to shuttle them into the Selected list.
4. Click OK.

   The new methods will appear in the Client Interface section of the Java Classes page.

Figure 13-21 shows multiple public methods added to the client interface.

Figure 13-21 Public Methods Added to an Application Module's Client Interface

When you publish custom service methods on the client interface, as shown in Figure 13-22, JDeveloper creates a Java interface with the same name as the application module in the common subpackage of the package in which your application module resides. For an application module named AppModule in the summit.model package, this interface will be named AppModule and reside in the summit.model.common package. The interface extends the base ApplicationModule interface in the oracle.jbo package, reflecting that a client can access all of the base functionality that your application module inherits from the ApplicationModuleImpl class.

Figure 13-22 Custom Client Interface Extends the Base ApplicationModule Interface

Description of "Figure 13-22 Custom Client Interface Extends the Base ApplicationModule Interface"

As shown in the following example, the AppModule interface includes the method signatures of all of the methods you've selected to be on the client interface of your application module.

package summit.model.appmodule.service.common;
import oracle.jbo.ApplicationModule;
// ---------------------------------------------------------------------
// ---    File generated by ADF Business Components Design Time.
// ---------------------------------------------------------------------
public interface AppModule extends ApplicationModule {
    String findOrderAndCustomer(long orderId);
    void updateOrderStatus(long orderId, String newStatus);
    String findOrderTotal (long orderId);
    long createCustomer(String name, String city, Integer countryId);
}

1. In the Applications window, double-click the view object for which you want to define the client interface.
2. In the overview editor, click the Java navigation tab and in the Client Interface section, click the Edit java options button.
3. In the Select Java Options dialog, click the Generate View Object Class and click the Generate View Row Class. Click OK.
4. In the overview editor, expand the Client Interface section and then click the Edit view object client interface button.
5. In the Edit Client Interface dialog, select one or more desired methods from the Available list and click the Add button to shuttle them into the Selected list.
6. In the overview editor, expand the Client Row Interface section and then click the Edit view object client row interface button.
7. In the Edit Client Interface dialog, select one or more desired methods from the Available list and click the Add button to shuttle them into the Selected list.
8. Click OK.

   The new methods will appear in the Java Classes page.

For example, if for the CustomerView view object in the summit.model.views package you were to enable the generation of a custom view object Java class and add one or more custom methods to the view object client interface, JDeveloper would generate the CustomerViewImpl class and CustomerView interface, as shown in Figure 13-23. As with the application module custom interface, notice that it gets generated in the common subpackage.

Figure 13-23 Custom View Object Interface Extends the Base ViewObject Interface

Description of "Figure 13-23 Custom View Object Interface Extends the Base ViewObject Interface"

Likewise, if for the same view object you were to enable the generation of a custom view row Java class and add one or more custom methods to the view row client interface, JDeveloper would generate the CustomerViewRowImpl class and CustomerViewRow interface, as shown in Figure 13-24.

Figure 13-24 Custom View Row Interface Extends the Base Row Interface

Description of "Figure 13-24 Custom View Row Interface Extends the Base Row Interface"

1. In the Applications window, right-click the application module and choose Run.

   Alternatively, choose Debug when you want to run the application in the Oracle ADF Model Tester with debugging enabled. The debugger process panel opens in the Log window and the various debugger windows. When debugging using the Oracle ADF Model Tester, you can use these windows to view status message and exceptions, step in and out of source code, and manage breakpoints.

   For information about receiving diagnostic messages specific to ADF Business Component debugging, see How to Enable ADF Business Components Debug Diagnostics.

2. To open the method testing panel for a method defined by a client interface, do one of the following:

   • In the data model tree, select the application module node and in the main menu choose View and then Operations when you want to execute a method you published for the application module client interface. You can also double-click the application module node to display the method testing panel.

   • In the data model tree, select the desired view object node and in the main menu choose View and then Operations when you want to execute a method you published on the client interface for a view object. You can also right-click the view object node and choose Operations.

3. To open the method testing panel for a method defined by a client row interface for a view object row, expand the data model tree, right-click the desired view object node and choose Show Table. Then in the overview panel for the view instance, select the desired row, and in the main menu, choose View and then Operations.

   Do not select a master view instance in the data model tree since view row operations are not permitted on master view objects. Always select a detail view instance or a view instance that is not specified in a master-detail hierarchy, as shown in Figure 13-25.

   Tip:

   In the case of a detail view instance, you can open the master view instance to navigate to the detail with the desired row. The Oracle ADF Model Tester automatically synchronizes the data displayed in the open overview panel with the master view instance that you navigate to.

   Figure 13-25 Menu Selection for View Row Operations in the Oracle ADF Model Tester

   
4. In the method panel, select the desired service method from the dropdown list, enter values to pass as method parameters, and click Execute.

   Notice that the method testing panel displays the parameter names to help you identify where to enter the values to pass. This is particularly useful when the method signature defines multiple parameters of the same data type.

   You can view the return value (if any) and test result. The result displayed in the Oracle ADF Model Tester will indicate whether or not the method executed successfully.

You can include any custom method in the client interface that obeys these implementation rules:

• If the method has a non-void return type, the type must be serializable.

• If the method accepts any parameters, all their types must be serializable.

• If the method signature includes a throws clause, the exception must be an instance of JboException in the oracle.jbo package.

In other words, all the types in its method signature must implement the java.io.Serializable interface, and any checked exceptions must be JboException or its subclass. Your method can throw any unchecked exception — java.lang.RuntimeException or a subclass of it — without disqualifying the method from appearing on the application module's client interface.

Note that method signatures of type java.util.List are allowed as long as the implementing class for the interface is serializable. For example, java.util.ArrayList and java.util.LinkedList are both serializable implementing classes. The same requirement applies to element types within the collection. The ADF Business Components runtime will produce an error if you instantiate a class that implements the interface yet does not implement the java.io.Serializable interface.

The private implementation of an application module custom method can easily refer to any view object instance in the data model using the generated accessor methods. By calling the getCurrentRow() method on any view object, it can access the same current row for any view object that the client user interface sees as the current row. As a result, while writing application module business service methods, you may not need to pass in parameters from the client. This is true if you would be passing in values only from the current rows of other view object instances in the same application module's data model.

For example, the custom application module method in the following example accepts no parameters. Internally, the createOrderItem() method calls getGlobals().getCurrentRow() to access the current row of the Globals view object instance. Then it uses the strongly typed accessor methods on the row to access the values of the Description and LineItemId attributes to set them as the values of corresponding attributes in a newly created OrderItem entity object row.

// In AppModuleImpl.java, createOrderItem() method
GlobalsRowImpl globalsRow = (GlobalsRowImpl)getGlobals().getCurrentRow();
newOrder.setDescription(globalsRow.getDescription());
newOrder.setLineItemId(globalsRow.getLineItemId());

To work programmatically with an application module's client interface, do the following:

• Cast ApplicationModule to the more specific client interface.

• Call any method on the interface.

The following example illustrates a TestClientEntity class that puts these two steps into practice. You could also use the main() method of this class to test application module methods, as described in How to Test the Custom Application Module Using a Static Main Method. Here you use it to call all of the same methods from the client using the AppModule client interface.

The basic logic of the following example follows these steps:

1. Retrieve the total for order 1011.

2. Retrieve the name of the customer for order 1011.

3. Set the status of order 1011 to the value "Y".

4. Create anew customer supplying a null customer name.

5. Create a new customer with a customer name and display its newly assigned customer ID.

package oracle.summit.model.appmodule.client;

import oracle.jbo.client.Configuration;
import oracle.jbo.*;
import oracle.jbo.domain.Number;
import oracle.jbo.domain.*;

import oracle.summit.model.appmodule.service.common.AppModule;

public class TestClientCustomInterface {
  public static void main(String[] args) {
      String amDef = "oracle.summit.model.appmodule.service.AppModule";
      String config = "AppModuleLocal";

      /*
       * This is the correct way to use application custom methods
       * from the client, by using the application module's automatically-
       * maintained custom service interface.
       */
      AppModule service =
               (AppModule)Configuration.createRootApplicationModule(amDef,config);
      String total = service.findOrderTotal(1011);
      System.out.println("Total for Order # 1011 = " + total);
      String custName = service.findOrderAndCustomer(1011);
      System.out.println("Customer for Order # 1011 = " + custName);
      try {
         service.updateOrderStatus(1011,"Y");
      }
      catch (JboException ex) {
         System.out.println("ERROR: "+ex.getMessage());
      }
      long id = 0;
      try {
         id = service.createCustomer(null, "Oakville", 14);
      }
      catch (JboException ex) {
         System.out.println("ERROR: "+ex.getMessage());
      }
      id = service.createCustomer("Oakville Curling Club", "Oakville", 14);
      System.out.println("New customer created successfully with id = " + id);
      Configuration.releaseRootApplicationModule(service,true);
  }
}

Running the custom application module class calls the main() method in the above example and produces the following output:

Total for Order # 1011 = 99.99
Customer for Order # 1011 = Customer: Zibbers, Location: Boston
ERROR: JBO-27014: You must provide a value for Name.
New customer created successfully with id = 133

Notice that the first attempt to call findOrderAndCustomer() with a null for the customer name raises an exception due to the built-in mandatory validation on the Name attribute of the Customer entity object.

Because the client layer accessing your application module will be located in the same tier of the Java EE architecture, the application module is deployed in what is known as local mode. In local mode, the client interface is implemented directly by your custom application module Java class. You access an application module in local mode whenever you access the application module in the web tier of a JavaServer Faces application.

The Configuration class in the oracle.jbo.client package makes it very easy to get an instance of an application module for testing. This eases writing test client programs like the test client program described in Regression Testing with JUnit as part of the JUnit regression testing fixture.

When working with Fusion web applications using the ADF Model layer for data binding, JDeveloper configures a servlet filter in your user interface project called the ADFBindingFilter. It orchestrates the automatic acquisition and release of an appropriate application module instance based on declarative binding metadata, and ensures that the service is available to be looked up as a data control using a known action binding or iterator binding, specified by any page definition file in the user interface project. You may eventually want to read about the ADF binding container, data controls, page definition files, and ADF bindings, as described in Using ADF Model in a Fusion Web Application. For now, it is enough to realize that you can access the application module's client interface from this DCBindingContainer by naming an ADF action binding or an ADF iterator binding. You can reference the binding context and call methods on the custom client interface in a JSF managed bean, as shown in the following examples for an action binding and for an iterator binding.

To access the custom interface of your application module using an action binding, follow these basic steps (as illustrated in the following example):

1. Access the ADF binding container.

2. Find a named action binding. (Use the name of any available action binding in the page definition files of the user interface project.)

3. Get the data control by name from the action binding.

4. Access the application module data provider from the data control.

5. Cast the application module to its client interface.

6. Call any method on the client interface.

package oracle.summit.model.viewobjects;

import oracle.summit.model.appmodule.service.common.SummitAppModule;
import oracle.adf.model.binding.DCBindingContainer;
import oracle.adf.model.binding.DCDataControl;
import oracle.jbo.ApplicationModule;
import oracle.jbo.uicli.binding.JUCtrlActionBinding;
public class YourBackingBean {
  public String commandButton_action() {
    // Example using an action binding to get the data control
    public String commandButton_action() {
    // 1. Access the binding container
    DCBindingContainer bc = (DCBindingContainer)getBindings();
    // 2. Find a named action binding
    JUCtrlActionBinding action = 
                    (JUCtrlActionBinding)bc.findCtrlBinding("SomeActionBinding");
    // 3. Get the data control from the iterator binding (or method binding)
    DCDataControl dc  = action.getDataControl();
    // 4. Access the data control's application module data provider
    ApplicationModule am = (ApplicationModule)dc.getDataProvider();
    // 5. Cast the AM to call methods on the custom client interface
    SummitAppModule service = (SummitAppModule)am;
    // 6. Call a method on the client interface
    service.doSomethingInteresting();
    return "SomeNavigationRule";
  }
}

To access the custom interface of your application module using an iterator binding, follow these basic steps (as illustrated in the following example):

1. Access the ADF binding container.

2. Find a named iterator binding. (Use the name of any iterator binding in the page definition files of the user interface project.)

3. Get the data control by name from the iterator binding.

4. Access the application module data provider from the data control.

5. Cast the application module to its client interface.

6. Call any method on the client interface.

package oracle.summit.model.viewobjects;

import oracle.summit.model.appmodule.service.common.SummitAppModule;
import oracle.adf.model.binding.DCBindingContainer;
import oracle.adf.model.binding.DCDataControl;
import oracle.adf.model.binding.DCIteratorBinding;
import oracle.jbo.ApplicationModule;
public class YourBackingBean {
  public String commandButton_action() {
    // Example using an iterator binding to get the data control
    public String commandButton_action() {
    // 1. Access the binding container
    DCBindingContainer bc = (DCBindingContainer)getBindings();
    // 2. Find a named iterator binding
    DCIteratorBinding iter = bc.findIteratorBinding("SomeIteratorBinding");
    // 3. Get the data control from the iterator binding
    DCDataControl dc  = iter.getDataControl();
    // 4. Access the data control's application module data provider
    ApplicationModule am = (ApplicationModule)dc.getDataProvider();
    // 5. Cast the AM to call methods on the custom client interface
    SummitAppModule service = (SummitAppModule)am;
    // 6. Call a method on the client interface
    service.doSomethingInteresting();
    return "SomeNavigationRule";
  }
}

These backing bean examples depend on the helper method shown in the following example.

public BindingContainer getBindings() {
{
        return BindingContext.getCurrent().getCurrentBindingsEntry();
}

If you create the backing bean class by overriding a button that is declaratively bound to an ADF action, then JDeveloper will automatically generate this method in your class. Otherwise, you will need to add the helper method to your class yourself.

1. In the Applications window, double-click the application module for which you want to override framework methods.
2. In the overview editor, click the Java navigation tab and then click the linked file name of the application module Java class that you want to customize.

   The class file opens in the source editor.

3. In the main menu, choose Source and then Override Methods.

   If the Source menu is not displayed, be sure that the desired Java class file is open and that the source editor is visible.

4. In the Override Methods dialog, scroll the list to locate the desired methods or type the first few letters of the method name to perform an incremental search.
5. Select one or more methods.

   The Override Methods dialog allows you to select any number of methods to override simultaneously.

   For example, if you wanted to override the application module's prepareSession() method to augment the default functionality when a new user session begins working with an application module service component for the first time, you would select the checkbox next to the prepareSession(Session) method, as shown in Figure 13-26.

   Figure 13-26 Overriding a Built-in Framework Method

   
6. Click OK.

When you dismiss the Override Methods dialog, you return to the source editor with the cursor focus on the overridden method, as shown in Figure 13-27. Notice that the method appears with a single line that calls super.prepareSession(). This is the syntax in Java for invoking the default behavior that the base class would have normally performed for this method. By adding code before or after this line in the custom application module class, you can augment the default behavior before or after the default functionality.

Figure 13-27 Source Editor Margin Gives Visual Feedback About Overridden Methods

Also notice that when you override a method using the Override Methods dialog, the source editor inserts the JDK @Override annotation just before the overridden method. This causes the compiler to generate a compile-time error if the method in the application module class does not match the signature of any method in the superclass.

Be careful when you add method names to your class to override a method in the superclass; you must have the signature exactly the same as the base class method you want to override. Be sure to add the @Override annotation just before the method. This way, if your method does not match the signature of any method in the superclass, the compiler will generate a compile-time error. Also, when you write code for a method instead of calling the superclass implementation, you should have a thorough understanding of what built-in code you are suppressing or replacing.

Since the prepareSession() method is invoked by the application module when it is used for the first time by a new user session, it's a useful method to override in your custom application module class to perform setup tasks that are specific to each new user that uses your application module. The following example illustrates an overridden prepareSession() method in the AppModuleImpl class that invokes a setApplicationInfo() helper method to specify database client information for the connected user.

public class AppModuleImpl extends SummitApplicationModuleImpl 
                           implements AppModule {
...

    @Override
    protected void prepareSession(Session session) {
        super.prepareSession(session);
        setApplicationInfo ("AppModuleImpl", "prepareSession");
        String username = this.getUserPrincipalName();
        System.out.println(username);
    }
    
    protected void setApplicationInfo(String clientInfo, String clientIdentifier){
        DBTransactionImpl dbti = (DBTransactionImpl)getDBTransaction();
        CallableStatement statement =
            dbti.createCallableStatement("BEGIN " 
          + "DBMS_APPLICATION_INFO.SET_CLIENT_INFO (client_info => :client_info);"
          + "DBMS_SESSION.SET_IDENTIFIER (:client_identifier);"
          + "END;", 0);
        try {
            statement.setString("client_info", clientInfo);
            statement.setString("client_identifier", clientIdentifier);
            statement.execute();
        } catch (SQLException sqlerr) {
            throw new JboException(sqlerr);
        } finally {
            try {
                if (statement != null) {
                    statement.close();
                }
            } catch (SQLException closeerr) {
                throw new JboException(closeerr);
            }
        }
    }
}

To call a web service from an application module, you create a web service proxy class for the service you want to invoke. A web service proxy is a generated Java class that represents the web service inside your application. It encapsulates the service URL of the web service and handles the lower-level details of making the call.

To work with a web service, you need to know the URL that identifies its WSDL document. If you have received the WSDL document as an email attachment, for example, and saved it to your local hard drive, the URL could be similar to:

file:///D:/temp/SomeService.wsdl

Alternatively, the URL could be an HTTP-based URL like:

http://someserver.somecompany.com/SomeService/SomeService.wsdl

Some web services make their WSDL document available by using a special parameter to modify the service URL. For example, a web service that expects to receive requests at the HTTP address of http://someserver.somecompany.com/SomeService might publish the corresponding WSDL document using the same URL with an additional parameter on the end, like this:

http://someserver.somecompany.com/SomeService?WSDL

Since there is no established standard, you will just need to know what the correct URL to the WSDL document is. With the URL information, you can then create a web service proxy class to call the service.

ADF Business Components services have URLs to the service of the following formats:

• On Integrated WebLogic Server, the URL has the format http://host:port/EJB-context-root/@WebService-name?WSDL, for example:

  http://localhost:8888/EJB-SummitService/SummitService?WSDL
  

• On Oracle WebLogic Server, the URL has the format http://host:port/context-root/@WebService-name?WSDL, for example:

  http://localhost:8888/SummitService/SummitService?WSDL
  

The web service proxy class presents a set of Java methods that correspond to the web service's public API. By using the web service proxy class, you can call any method in the web service in the same way as you work with the methods of any other local Java class.

To call a web service from an application module using a proxy class, you perform the following tasks:

1. Create a web service proxy class for the web service. To create a web service proxy class for a web service that you need to call, use the Create Web Service Client and Proxy wizard.

2. Implement the methods in the proxy class to access the desired web services.

3. Create an instance of the web service proxy class in your application module and invoke one or more methods on the web service proxy object.

JDeveloper generates the web service proxy class in the package you've indicated with a name that reflects the name of the web service port it discovered in the WSDL document. The web service port name might be a human-readable name like StockQuoteService, or could be a less-friendly name like StockQuoteServiceSoapHttpPort. The port name is decided by the developer that published the web service you are using. If the port name of the service were StockQuoteServiceSoapHttpPort, for example, JDeveloper would generate a web proxy class named StockQuoteServiceSoapHttpPortClient.

The web service proxy displays in the Applications window as a single, logical node called WebServiceNameProxy. For example, the node for the StockQuoteService web service would appear in the Applications window with the name StockQuoteServiceProxy. As part of generating the proxy class, in addition to the main web service proxy class that you use to invoke the server, JDeveloper generates a number of auxiliary classes and interfaces. You can see these files in the Applications window under the WebServiceNameProxy node. The generated files are used as part of the lower-level implementation of invoking the web service.

The only auxiliary generated classes you need to reference are those created to hold structured web service parameters or return types. For example, imagine that the StockQuoteService web service has a quoteForSymbol() method that accepts one String parameter and returns a floating-point value indicating the current price of the stock. If the designer of the web service chose to return a simple floating-point number, then the web service proxy class would have a corresponding method like this:

public float quoteForSymbol(String symbol)

If instead the designer of the web service thought it useful to return multiple pieces of information as the result, then the service's WSDL file would include a named structure definition describing the multiple elements it contains. For example, assume that the service returns both the symbol name and the current price as a result. To contain these two data elements, the WSDL file might define a structure named QuoteInfo with an element named symbol of string type and an element named price of floating-point type. In this situation, when JDeveloper generates the web service proxy class, the Java method signature would instead look like this:

public QuoteInfo quoteForSymbol(String symbol)

The QuoteInfo return type references one of the auxiliary classes that comprises the web service proxy implementation. It is a simple bean whose properties reflect the names and types of the structure defined in the WSDL document. In a similar way, if the web service accepts parameters whose values are structures or arrays of structures, then you will work with these structures in your Java code using the corresponding generated beans.

1. In the Applications window, right-click a web service proxy and choose Create ADF Web Service Connection.

   The New ADF Web Service Connection dialog displays the default settings for a connection associated with the selected proxy.

2. Modify the connection information as necessary, and click OK.

Context ctx = ADFContext.getCurrent().getConnectionsContext();

WebServiceConnection wsc = (WebServiceConnection) ctx.lookup("MyAppModuleService");

MyAppModuleService proxy = wsc.getJaxWSPort(MyAppModuleService.class);

When you invoke a web service from an application module, the web service proxy class handles the lower-level details of using the XML-based web services protocol described in SOAP. In particular, it does the following:

• Creates an XML document to represent the method invocation

• Packages any method arguments in XML

• Sends the XML document to the service URL using an HTTP POST request

• Unpackages the XML-encoded response from the web service

If the method you invoke has a return value, your code receives it as an appropriately typed object to work with in your application module code.

When you are implementing web service proxies in an application, you might want to use a try-catch block to handle web service exceptions or invoke an application module with a web service proxy class. The following sections contain additional information you might need to know about these and other features with regard to web service proxies.