12 J2ME Development and Provisioning

12.1.1.1 Minimum Memory Requirement in the MIDlet Suite

MIDlets are packaged and deployed as MIDlet Suite. Each MIDlet suite contains the MIDlet's JAR file and its descriptor (JAD) file. The J2ME Client Library client JAR file requires only 26 KB of memory in a MIDlet suite. A currently available alternative is kSOAP 1.2, which is 41 KB and requires kXML, which adds another 21 KB for a total size of 62 KB.

The proxy server enables the 36 KB memory requirement because the server performs the operations on the Web services, thereby reducing the amount of work performed by MIDP device.

12.1.1.2 Simple Registration and Invocation of Web Services

The entire process of a J2ME MIDlet calling a Web service consists of:

1. Registering a Web service with the J2ME Proxy Server using the Web service's WSDL (Web Services Definition Language) document.

2. Generating a J2ME client stub class for the registered service.

3. Calling a Java method on the generated stub class from your J2ME MIDlet. Each method in the generated J2ME client stub represents an operation of the Web service. For example, a MIDlet compiled with the J2ME Client Library JAR file makes a request to a Web service simply by making a Java method call.

12.1.1.3 Access to Both SOAP Web Services and Enterprise Applications

To register SOAP Web services with the J2ME Proxy Server, you provide the file location of the Web service's WSDL document. During WSDL Registration, the J2ME Proxy Server generates a SOAP client Java class. During execution, the J2ME Proxy Server calls this client class to invoke operations on the Web service.

The J2ME Proxy Server also supports a second type of registration called Class Registration, which enables you to register any Java class with the J2ME Proxy Server. This enables you to access enterprise applications from J2ME MIDlets by creating a Java client to these applications. Once you register this Java client with the J2ME Proxy Server, all of the public methods of the Java class become available for invocation from the J2ME MIDlet.

12.1.1.4 Result Caching and Call Queuing

The methods in the generated J2ME client stub classes contain additional parameters that allow you to cache the result from a Web service call in local persistent storage on the MIDP device. This enables the MIDlet to access the results returned from the Web service repeatedly without requiring additional network round-trips, even after the device has been turned off or has been moved to an area without network access.

Call queuing enables you to queue Web service operation invocations if a network error prevents calling a Web service normally. The J2ME Client Library runtime automatically retries the queued calls until they succeed, and then caches the responses in persistent storage until MIDlet retrieves them.

12.1.1.5 Request and Response Packetization and Compression

Request packetization enables you to specify a maximum request size for cases in which a wireless network cannot handle HTTP requests that exceed a certain size. The J2ME Client Library and J2ME Proxy Server automatically break up call requests and responses into pieces no larger than the maximum specified size.

The J2ME Client Library and J2ME Proxy Server compress requests and responses for improved bandwidth and memory usage. Requests and responses are encoded to reduce their size during network transmission and when cached in the MIDlet. This is done automatically.

12.1.1.6 Session Support

Session support is activated by default, meaning that an instance of the Java class registered with the J2ME Proxy Server (a class that was either generated during WSDL Registration or provided during Class Registration) is stored in an HttpSession object and then reused when the J2ME Proxy Server receives multiple requests from the same MIDlet. Session support can be turned off by setting a property in the J2ME Client Library.

12.1.1.7 Deployment to OracleAS Wireless

Once you complete the development of a MIDlet, the J2ME MIDlets and the Web services registered with the J2ME Proxy Server can be easily deployed to a complete OracleAS Wireless installation. The WDK and OracleAS Wireless contain migration scripts to facilitate this deployment.

12.1.2.1 Setup

The OracleAS Wireless Proxy Server consists of two sets of components: the actual server and the scripts to manage the server.

1. First launch the WDK server, which includes the J2ME Proxy Server, by executing the following script:

   Windows: ORALCE_HOME\opmn\bin\opmnctl start wdk

   UNIX: ORACLE_HOME/opmn/bin/opmnctl.sh start wdk

2. If you are running the Wireless Development Kit behind a firewall, you must also configure your HTTP proxy server settings in the j2mesdkmgr.bat (Windows) and j2mesdkmgr.sh (UNIX) scripts, located in ORACLE_HOME\wireless\bin/. The scripts contain commented-out examples for setting the HTTP proxy server for -registerwsdl option. If you want to register Java classes as services and the classes are at URLs which are outside of your firewall, you must also include HTTP proxy server settings in the –registerclass option of above scripts. As illustrated in the examples for the -registerwsdl option, setting the HTTP proxy server consists of defining the following variables in the Java command line:

   Dhttp.useProxy=true -Dhttp.proxyHost=<http proxy server>
   Dhttp.proxyPort=<port number> -Dhttp.nonProxyHosts=<hosts inside firewall>
   
   

12.1.2.2 J2ME Directory Structure in the WDK

The following are the WDK directories relevant to the J2ME Client Library and J2ME Proxy Server.

• wireless/-- (OracleAS Wireless and WDK home)

  • bin/ (scripts for registration and management of Web services)

  • lib/ (libraries and properties files)

  • j2me/-- (J2me sdk home)

    • docs/Javadoc (J2me SKD API documentation)

    • lib/ (contains J2me DK JAR file)

    • sample/ (sample MIDlets and WSDL files)

• j2ee/OC4J_Wireless/-- (OracleAS Wireless J2EE base)

  • applications/wdk/wdk-Web/Webservice -- (J2ME proxy server home)

    • repository/ (descriptions of registered Web services)

    • stage/ (source of classes generated during WSDL registration)

    • classes/ (compiled classes generated during WSDL registration)

    • lib/ (contains jar file with test services used by sample MIDlets)

    • src/ (source code)

12.1.3.1 Step 1: Register a Web Service with the J2ME Proxy Server

You can register a Web service either through Web Service Registration or through Class Registration.

For Web Service Registration, you registering Web services with the J2ME Proxy Server to make those Web services accessible to J2ME MIDlets. You register a SOAP Web service with the J2ME Proxy Server by providing the WSDL document describing the Web service. Once registered, the Web service is available to J2ME MIDlets by calling methods of a J2ME stub class generated from the registered service.

In addition to registering SOAP Web services, you can also register any Java class with the J2ME Proxy Server using Class Registration. All of the public methods of the Java class become available for remote invocation from your MIDlet. This enables you to give your MIDlets access to any enterprise application simply by building a Java client to the enterprise application. This Java class must have either a public constructor with no arguments or a public static method called getInstance() with no arguments that returns an instance of the class.

Namespaces

When registering Web services, you can group them into namespaces. Associating services with a namespace enables you to group related Web services and to avoid naming conflicts. If you do not specify a namespace, then the Web service is registered under the default namespace.

WSDL Registration Script Option (registerwsdl)

j2mesdkmgr –registerwsdl registers a Web service using the Web service's WSDL document.

Usage:

j2mesdkmgr –registerwsdl <URL of the WSDL> [<namespace>]

For example, to register the Hello World service (hello.wsdl) available from the Oracle Technology Network (OTN), execute:

For Windows:

j2mesdkmgr.bat –registerwsdl http://www.oracle.com/technology/tech/Webservices/htdocs/live/hello.wsdl

For UNIX:

j2mesdkmgr.sh –registerwsdl http://www.oracle.com/technology/tech/Webservices/htdocs/live/hello.wsdl

To register the service inside a namespace, use the namespace as the third parameter to the script. For example, to register the Hello World application in a namespace called samples, execute:

For Windows:

j2mesdkmgr.bat –registerwsdl http://www.oracle.com/technology/tech/Webservices/htdocs/live/hello.wsdl samples

For UNIX:

j2mesdkmgr.sh –registerwsdl http://www.oracle.com/technology/tech/Webservices/htdocs/live/hello.wsdl samples

Class Registration Script Option (registerclass)

j2mesdkmgr –registerclass registers a Web service using a Java class.

Usage:

j2mesdkmgr -registerclass <URL of the Class Library> <Name of the class> [<namespace>]

The first parameter must be a URL. It may point to either a directory containing the class or to a JAR file.

The second parameter must be a fully qualified class name. For example, to register a service called TestWebService (which is included in the WDK), execute:

For Windows:

j2mesdkmgr.bat -registerclass file:C:\ora9ias\j2ee\OC4J_Wireless\applications\wdk\wdk-Web\Webservice\lib\testservices.jar oracle.wireless.me.server.TestWebService

For UNIX:

j2mesdkmgr.sh -registerclass file:/ias/j2ee/OC4J_Wireless/applications/wdk/wdk-Web/Webservice/lib/testservices.jar oracle.wireless.me.server.TestWebService

To register the service inside a namespace, use the namespace as the fourth parameter to the script. For example, to register the TestWebService class in the samples namespace, execute:

For Windows:

j2mesdkmgr.bat -registerclass file:C:\ora9ias\j2ee\OC4J_Wireless\applications\wdk\wdk-Web\Webservice\lib\testservices.jar oracle.wireless.me.server.TestWebService samples

For UNIX:

j2mesdkmgr.sh -registerclass file:/ias/j2ee/OC4J_Wilreless/applications/wdk/wdk-Web/Webservice/lib/testservices.jar oracle.wireless.me.server.TestWebService samples

12.1.3.2 Step 2: Generate J2ME Client Stub Class for the Registered Web Service

The simplest way to call a Web service that you have registered with the J2ME Proxy Server from your MIDlet is to generate a J2ME stub for the service and to call the methods of the generated stub from your MIDlet.

Stub Generation Script Option (-generatestub)

j2mesdkmgr -generatestub generates a J2ME client stub class for a registered Web service.

Usage:

j2mesdkmgr -generatestub [<namespace>.]<service name> [<Output directory> [<stub name>]]

For example, to generate a J2ME stub class for the Hello World service available from the Oracle Technology Network (IOTNHelloWorld):

j2mesdkmgr -generatestub IOTNHelloWorld

If the service is inside a namespace, you must prefix the service name with the namespace and a period (.). For example, if the Hello World service (IOTNHelloWorld) is registered inside the samples namespace, generate the stub with:

j2mesdkmgr -generatestub samples.IOTNHelloWorld

You can specify a directory in which to place the generated stub as a third parameter to the script.

If you do not specify a stub name, then the generated J2ME client stub class will be called:

IOTNHelloWorldJ2MEStub.Java

To specify a different name for the generated stub, specify an output directory as the third parameter (tmp in the following examples) and the desired stub class name (HelloWord in the following examples) as the fourth parameter. For example:

For Windows:

j2mesdkmgr.bat -generatestub samples.IOTNHelloWorld c:\tmp HelloWorld

For UNIX:

j2mesdkmgr.sh -generatestub samples.IOTNHelloWorld /tmp HelloWorld

The generated J2ME client stub class contains one method for each operation of the Web service.

12.1.3.3 Step 3: Calling the Methods in the J2ME Stub Class from the MIDlet

Each of the public methods in the generated J2ME stub class represents an operation of a registered service. The first two parameters of each method have special meaning to J2ME Client Library: the first parameter is the number of minutes to cache the response; the second parameter is a boolean, which should be set to true to bypass any cached responses (that is, force the J2ME Client Library to make a network call to the Web service), and set to false to use a cached response if available and valid. For more information about these parameters, see Section 12.1.4.1, "Response Caching".

All of the other parameters of the methods in the generated stub correspond to the parameters of the service operation that the method represents. Calling these methods from your MIDlet invokes these operations on the Web service.

To test your MIDlet with Sun's J2ME Wireless Toolkit (http://java.sun.com/products/j2mewtoolkit/download.html):

1. Create a project for your MIDlet. Put the J2ME Client Library JAR file j2me_sdk.jar in the lib directory of your project. Put the generated J2ME stub class in the src directory of your project.

2. In the source code of your J2ME MIDlet, enter an import statement for the generated J2ME stub class, create an instance of the stub class, and make calls to the methods in the stub class. The first parameter of each stub method is the number of minutes to cache the result. Set 0 for no caching, or -1 to cache forever. The second parameter of each stub method is true to ignore cached results (that is, always make a network call), or false to use valid cached results if available. The remaining parameters of the stub methods correspond to the parameters of the Web service operations represented by the methods.

3. Build and run your J2ME MIDlet.

12.1.3.4 Using TestStubMidlet to Access Simple Services

The J2ME Client Library provides a sample J2ME MIDlet, called TestStubMidlet, which enables you to quickly test the generated stub files for the Web services that you register with the J2ME Proxy Server.

To use the sample TestStubMidlet:

1. Download and install Sun's J2ME Wireless Toolkit at http://java.sun.com/products/j2mewtoolkit/download.html

2. Make the following modifications to the sample MIDlet file TestStubMidlet.Java, which is located in:

   ORACLE_HOME/wireless/j2me/j2mesdk/sample/

   1. Add an import statement for the generated Java stub class.

   2. Modify the callStub()method to instantiate the stub class, call the operation, and assign the result to the instance variable sCallResultString, used to display the result.

3. Create a Project in Sun's J2ME Wireless Toolkit. (You must first locate the OracleJ2ME Web Service Client Library, j2me_sdk.jar, which is located in ORACLE_HOME/wireless/wdk/j2me/lib/)

   Place this library inside the lib directory of the project. Place the stub class in the src directory of the project, and place the modified TestStubMidlet class in an oracle/wireless/me/sample1/ subdirectory inside the src directory of the project (TestStubMidlet is in the package oracle.wireless.me.sample1)

4. Build and run the project. When the J2ME device emulator appears, launch the test MIDlet and execute Call Stub. The test result then appears.

   Example:

   This example uses TestStubMidlet to call the XMethods Delayed Stock Quote Web service to display a stock quote for Oracle Corporation:

   1. Register the XMethods Delayed Stock Quote Web service (xmethods-delayed-quotes.wsdl):

      j2mesdkmgr -registerwsdl http://services.xmethods.net/soap/urn:xmethods-delayed-quotes.wsdl

   2. Generate the stub:

      j2mesdkmgr -generatestub NetXmethodsServicesStockquoteStockQuoteService

   3. Modify TestStubMidlet.Java as in Example 12-1.

      Example 12-1 Modifying TestStubMidlet.java

      ...
      import NetXmethodsServicesStockquoteStockQuoteServiceJ2MEStub;
      ...
      /**
      * Call Stub. Edit this method to test the stub.
      * Remember to import the stub class
      */
      private void callStub()
      {
        try {
          // Add your code to test the stub.
          // For example:
          // Use the stub to call the XMethods delayed stock quote service to get
          // Oracle's stock price and cache the result for 1 minute.
          // Instantiate the Stub class:
          NetXmethodsServicesStockquoteStockQuoteServiceJ2MEStub stub =
             new NetXmethodsServicesStockquoteStockQuoteServiceJ2MEStub();
       
          // Call GetQuote Operation to get Oracle's stock price and
          // cache the result for 1 minute
          sCallResultString = new String("Stock price for ORCL :" +
               stub.getQuote(1, false, "ORCL"));
        }
      ...
      

   4. Build and run. The delayed stock quote for Oracle appears on the test result screen. If you invoke the stub a second time within one minute, the result appears quickly, since it is reading from the local cache without making a round trip to the network.

http://www.oracle.com/technology/tech/Webservices/htdocs/live/hello.wsdl

12.1.4.1 Response Caching

The first two parameters of every public method in a generated stub are int timetokeep and boolean refresh. These parameters are used to control response caching. The J2ME Client Library is able to cache the response of a Web service operation in persistent memory on the wireless device. For future invocations of the same operation, the response is retrieved from the local cache instead of from the Web service.

int timetokeep

This is the time in minutes to keep the response in the cache. Further invocations of the same operation within the specified number of minutes will retrieve the response from the local cache instead of making a network round-trip to the Web service. After the specified number of minutes has elapsed, the response in the cache becomes invalid, and the next invocation of this operation will again make a network round-trip to the Web service. Set this parameter to 0 to disable caching, or to –1 to cache forever (the response never becomes invalid).

boolean refresh

This parameter indicates whether to bypass the cache when invoking this operation. Setting this parameter to true forces a network round-trip, even if a valid response is available in the local cache. If this parameter is false, the response if retrieved from the local cache if an available cached response is valid.

12.1.4.2 HTTP Authentication

The J2ME Proxy Server and Client Library support accessing Web services that use the HTTP basic authentication scheme. To set the username and password for authentication, update the Web services' generated stub, setting the instance variables userName and password to the appropriate values. This username and password will be passed to the Web service's HTTP server by the proxy server for authentication.

12.1.4.3 Session Support

Session support is activated by default. To disable session support, update the Web services' generated stub, setting the enableSession instance variable to false. The J2ME Proxy Server uses a Java class to invoke operations on the Web service whether you use WSDL Registration or Class Registration to register a Web service with the J2ME Proxy Server, Session support means that successive invocations of operations of a Web service coming from the same J2ME device use the same instance object of this Java class. The instance of the class is saved in the J2ME Proxy Server's servlet HttpSession object, so it is available as long as the HTTP session is valid.

12.1.4.4 Request and Response Packetization

The J2ME Client Library sends requests to the J2ME Proxy Server using HTTP, the only protocol that is guaranteed to support all MIDP implementations. Some wireless carriers are unable to correctly send an HTTP request if it exceeds a certain size. To work around this problem, the J2ME Client Library enables you to specify a maximum size in bytes for the request and response. In the J2ME stub generated for a Web service, edit the maxRequestSize instance variable to set the maximum HTTP request and response size in bytes.

12.1.4.5 Client Library API

In most cases, you can use the server-generated client stub to invoke services registered with the J2ME Proxy Server. If you want to use an advanced feature such as call queuing, however, you must use the Client Library API directly, either from your own MIDlet, or by modifying the generated stub.

The API documentation for the J2ME Client Library is located at:

ORACLE_HOME\wireless\j2me\Javadoc\index.html

// Get the URL of the J2ME proxy server.
String servURL = getAppProperty("j2me_proxy_url");
if (servURL == null) {
servURL = "http://localhost:9010/wdk/proxy";
System.out.println("Unable to get j2me_proxy app property, using
default: " + servURL);
}
ServiceFactory serviceFactory = ServiceFactory.getInstance();
Service service = serviceFactory.createService(servURL,Service.DEFAULT_NAMESPACE,"TestWebService");

// Set cache timeout to 1 hour.
Call call = service.createCall("hello", 60);

// Put the parameters in a Vector.
Vector params = new Vector();
params.addElement( new String("World") );
Response response = call.invoke(params, false);

// Check if the response is valid (0 = OK).
int retCode = response.getReturnCode();
String retVal;
if (retCode == 0) {
  retVal = response.getString();
}
else { // return code not 0
  retVal = "Call unsuccessful: " + response.getErrorMsg();
}

try {
   Response response = call.invoke(params, false);
...
catch (ServiceException se) {
   if (se.getErrorCode() == ServiceException.CONNECTION_FAILED) {
      int queuedId = ServiceManager.getInstance().queueCall(call);
   }
   ...
}
...

int[] queuedIds = ServiceManager.getInstance().getQueuedCalls( true );
for (int i = 0; i < queuedIds.length; i++){
  //Retrieve Call object
  Call invokedCall =
     ServiceManager.getInstance().getQueuedCall(queuedIds[i]);
  Response response = invokedCall.getResponse();
  ...
}

...
int[] queuedIds = ServiceManager.getInstance().getQueuedCalls( false );
...

  private void exitMIDlet()
  {
    try {
      ServiceManager.getInstance().close();
    }
    catch (Exception e) {
    }
 
    notifyDestroyed();
  }
    
 
  protected void destroyApp(boolean unconditional)
     throws MIDletStateChangeException
  {
     exitMIDlet();
  }
 
 
  public void commandAction(Command c, Displayable d)
  {
     if (c == exitCommand) {
  exitMIDlet();
 }
             . . . 
 }

12.1.4.6 Deploying MIDLets to OracleAS Wireless

When you have finished developing and testing your Web service-enabled J2ME MIDlets using the Wireless Development Kit, you can deploy them on a real OracleAS Wireless installation. You can do this by either one of the following two methods.

private String _proxyUrl= "http://example.com:7777/mcs/wsproxy/proxy"; 

12.1.4.7 Deploying through scripts

You can avoid reregistering every Web service that your MIDlets access by using the migration scripts. The process consists of downloading, or exporting, all information on the registered Web services to an XML file, and then uploading, or importing, this information from the XML file to a OracleAS Wireless installation.

1. Export the Web services registered with the WDK J2ME Proxy Server to an XML file using the following script:

   migrateStandalone

   This script is used to extract Web services registered with the WDK J2ME Proxy Server into an XML file. This script is located with the other WDK J2ME Proxy Server scripts for registration and management of Web services, at ORACLE_HOME/wireless/wdk/bin.

   Usage:

   j2mesdkmgr -export <xml file name>

   Examples:

   For Windows:

   j2mesdkmgr -export C:\temp\registered_services.xml

   For UNIX:

   j2mesdkmgr.sh -export /usr/tmp/registered_services.xml

2. Import the XML file to a OracleAS Wireless installation, using the following script:

   uploadJ2MEProxy

   This script takes a single parameter: the name or full path to an XML file produced by the j2mesdkmgr -export script. All of the Web services described in this XML file are inserted into the database of this OracleAS Wireless and become registered with the J2ME Proxy Server of this OracleAS Wireless installation. This script is located in the directory ORACLE_HOME/wireless/bin/.

   Usage:

   uploadJ2MEProxy <xml file name>

   Examples:

   For Windows:

   uploadJ2MEProxy.bat c:\temp\registered_services.xml

   For UNIX:

   uploadJ2MEProxy.sh /usr/tmp/registered_services.xml

3. Generate new J2ME stubs for the Web services that your MIDlets call.

   You can skip this step by manually modifying the J2ME stubs that you already have (Do this if you made any manual modifications to the generated stubs.). You must change the value of the _proxyUrl instance variable to the correct hostname of the OracleAS Wireless server, the correct port number (typically 7777), and the correct path: /mcs/wsproxy/proxy. For example:

   private String _proxyUrl= "http://example.com:7777/mcs/wsproxy/proxy"; 
   
   

4. Recompile your MIDlets with the new or corrected J2ME stubs.

12.1.4.8 Migration from One OracleAS Wireless Installation to Another

At some point, you may want to migrate all of the information on Web services registered with the J2ME Proxy Server from one OracleAS Wireless installation to another. The process consists of downloading, or exporting, all information on the registered Web services of the source OracleAS Wireless to an XML file, and then uploading, or importing, this information from the XML file to the destination OracleAS Wireless. The scripts to do this are found in the following directory:

ORACLE_HOME/wireless/bin/

To migrate the information on Web services registered with the J2ME Proxy Server from on OracleAS Wireless installation to another:

1. Export the Web services registered with the source OracleAS Wireless J2ME Proxy Server to an XML file, using the following script:

   downloadJ2MEProxy

   This script takes a single parameter: the name or full path to an XML file. All Web services registered with the J2ME Proxy Server on the OracleAS Wireless where this script is run are extracted from the OracleAS Wireless database and placed into this XML file.

   Usage:

   downloadJ2MEProxy <xml file name>
   
   

   Examples:

   For Windows:

   downloadJ2MEProxy.bat c:\temp\registered_services.xml

   For UNIX:

   downloadJ2MEProxy.sh /usr/tmp/registered_services.xml

2. Import the XML file to the destination OracleAS Wireless J2ME Proxy Server, using the following script:

   uploadJ2MEProxy

   This script takes a single parameter: the name or full path to an XML file produced by the downloadJ2MEProxy script. All of the Web services described in this XML file are inserted into the database of the OracleAS Wireless where this script is run and become registered with the J2ME Proxy Server of this OracleAS Wireless installation.

   Usage:

   uploadJ2MEProxy <xml file name>

   Examples:

   For Windows:

   uploadJ2MEProxy.bat c:\temp\registered_services.xml

   For UNIX:

   uploadJ2MEProxy.sh /usr/tmp/registered_services.xml

3. Generate new J2ME stubs for the Web services that your MIDlets call.

   You can skip this step by manually modifying the J2ME stubs that you already have (Do this if you made any manual modifications to the generated stubs.). Change the value of the _proxyUrl instance variable. Update this URL with the correct hostname of the OracleAS Wireless server, the correct port number (typically 7777), and the correct path (/mcs/wsproxy/proxy). For example: private String _proxyUrl= "http://example.com:7777/mcs/wsproxy/proxy";

4. Recompile your MIDlets with the new (or corrected) J2ME stubs.

12.2.2.1 Use Case Study

The following sections describe an example of PoweredByPolicy, where a splash screen is packaged with the associated applications.

package devguide;
 
import Java.io.IOException;
import Javax.microedition.midlet.*;
import Javax.microedition.lcdui.*;
import oracle.wireless.me.drm.DRMAgent;
 
/**
* <code>PoweredByPolicy</code> displays a "Powered By" splash 
* screen for a packaged content. The product copyright string may 
* be set using a property parameter using OracleAS Wireless Server.
*/ 
public class PoweredByPolicy extends DRMAgent implements CommandListener {
 
/**
* value of copyright
*/
private String copyright;
 
public PoweredByPolicy(MIDlet ctx) {
super(ctx);
copyright = getProperty("copyright");
}
 
/**
* Displays a splash screen when the application starts up.
*/
public void onStartApp() {
showSplash();
}
 
/**
* Creates a splash screen and sets it be the current display
*/
private void showSplash() {
Form form = new Form("Powered By:");
try {
form.append(Image.createImage("/devguide/9i.png"));
}
catch(IOException ioe){
form.append("Oracle AS Wireless");
}
form.append(copyright);
form.addCommand( new Command("OK", Command.SCREEN, 1));
form.setCommandListener(this);
Display.getDisplay(context).setCurrent(form);
}
 
/**
* Resume the normal application logic when user 
* attends to the splash screen
*/
public void commandAction(Command c, Displayable d) {
resumeStartApp();
}
} // end of class PoweredByPolicy 

The PoweredByPolicy class defines an implementation of oracle.wireless.me.drm.DRMAgent (referred to as DRMAgent hereafter). It defines a constructor with a single argument of type Javax.microedition.midlet.MIDlet to satisfy the general contract of DRMAgent, The implementation of onStartApp() method displays a splash screen by calling the showSplash() method that houses the business logic of the policy. Finally, the event handler of splash screen calls resumeStartApp() for the packaged application to resume normally.

You can use the Sun J2ME Wireless Toolkit to compile and pre-verify the PoweredByPolicy class. The required lib containing DRMAgent class can be obtained from <IASW_HOME>/wireless/lib/j2medrm_demo.jar. The compiled and pre-verified class file or JAR file (which must also be pre-verified) containing the class file can be packaged by defining a packager as explained in Section 12.2.2.1.1.

public byte[] packageDRMContent(byte[] content, Properties policyProperties, Document odrlXml,UserDevice device)

package devguide;
 
import oracle.wireless.me.server.tools.drm.J2MEDRMPackager;
import oracle.wireless.me.server.tools.drm.DRMPackager;
import Java.util.Properties;
 
/**
 * Powered By Rights Packager
 */
public final class PoweredByPolicyPackager extends J2MEDRMPackager {
  private static Properties defaultInitProperties = null;
 
  static {
    defaultInitProperties = new Properties();
    // initializes the copyright property with a default value
    defaultInitProperties.setProperty("copyright", "Copyright 2003 Oracle Corporation. All Rights Reserved.");
  }
 
  private Properties initProperties = null;
 
  private static PoweredByPolicyPackager instance = new PoweredByPolicyPackager();
 
  /**
   * Static factory that returns the instance of DRMPackager
   */
  public static DRMPackager getInstance() {
    return instance;
  }
 
  private PoweredByPolicyPackager() {
    initProperties = defaultInitProperties;
    setDRMAgentInfo("devguide.PoweredByPolicy", "C:\\temp\\poweredby.jar");
  }
 
  public Properties getInitPropertiesDef() {
    return defaultInitProperties;
  }
}// end of the class

  public static DRMPackager getInstance() {
    return instance;
  }