Connectivity Between a BEA Tuxedo CORBA Client and an EJB in WebLogic Server

This topic includes the following sections:

Overview of the WLStrader Value Type Sample Application

The WLStrader Value Type sample application demonstrates connectivity between an RMI over IIOP client and an EJB. More specifically, this sample application illustrates how a CORBA C++ client application developed in BEA Tuxedo can interact with an EJB in WebLogic Server. The application makes use of the Trader EJB included in the WebLogic Server examples. The WLStrader Value Type sample builds on components of the Trader sample application, while providing its own build and run procedures.

Figure 2-1 CORBA C++ Client to WebLogic Server EJB

Components of the WLStrader Value Type Sample Application

This topic describes the components and operations in the WLStrader Value Type sample application. It includes the following sections:

WebLogic Server Trader Sample Application

The WLStrader Value Type sample builds on components of the WebLogic Server Trader sample application, employing its XML deployment files and Trader EJB. To derive the optimum benefit from this example, read through the source code files to understand the design and the steps involved. Review the deployment files to understand the general structure of the Trader EJB.

The WebLogic Server code sample files for the Trader sample are in the wlserver6\samples\examples\rmi_iiop\ejb\rmi_iiop directory.

Table 2-1 Java Interface Summary

Java Interface	Description
Trader	The methods in this interface are the public face of TraderBean.
TraderHome	This interface is the home interface for TraderBean.java, which in WebLogic is implemented by the code-generated container class TraderBeanC.

Table 2-1 provides a summary of the Java interfaces in this example.

Table 2-2 Java Class Summary

Java Class	Description
Tuxclient	This C++ client program logic invokes a stateless Session Bean and performs the following exercises: creates a Trader, buys some shares using the Trader, retrieves the NumberTraded returned in a value type, and removes the Trader.
TraderBean	TraderBean is a stateless Session Bean.
TradeResult	This class implements the serializable interface, and does not have any classes generated on the value type. The state of TradeResult is maintained in private instance members, and there is no default public access to the state of the value type. Because TradeResult implements the serializable interface, the ejbc utility generates a value type for it in the IDL file.

Table 2-2 provides a summary of the Java classes in this example.

Mapping from a WebLogic Server to a CORBA Client

When deriving the mapping from a WebLogic Server application to a CORBA client, the sources of the mapping information are the EJB classes as defined in the Java source files. WebLogic Server provides the weblogic.ejbc utility for generating required CORBA IDL files. These files represent the CORBA view into the state and behavior of the target EJB.

The weblogic.ejbc utility performs the following:

The weblogic.ejbc utility supports a number of command qualifiers. In the WLStrader Value Type example, the ejbc step invokes these qualifiers on the command line:

Resulting files are processed using the BEA Tuxedo IDL compiler, reading source files from the idlSources directory and generating CORBA C++ stub and skeleton files. These generated files are sufficient for all CORBA data types with the exception of value types. Value types need to be implemented on each platform on which they are defined or referenced. Specifying the -i qualifier directs the IDL compiler to create implementation files named FileName_i.h and FileName_i.cpp. For example, this syntax creates the TradeResult_i.h and TradeResult_i.cpp implementation files:

idl -IidlSources -i idlSources\examples\rmi_iiop\ejb\rmi_iiop\TradeResult.idl

The resulting source files provide implementations for application-defined operation on a value type. Implementation files are included in a CORBA client application.

BEA Tuxedo CORBA C++ Client

The CORBA C++ client program tuxclient performs the exercises against the Trader. The results from a Trader transaction are returned to the client through the TradeResult value type. The tuxclient application performs these operations:

Listing 2-2 tuxclient.cpp—Create a Trader; Buy Some Shares

 . . .
// Create a Trader instance
::examples::rmi_iiop::ejb::rmi_iiop::Trader_ptr trader = 
     home->create();

// Buy some shares
CORBA::WStringValue_ptr BEASsym = new
    CORBA::WStringValue(CORBA::wstring_dup((wchar_t *)L"BEAS"));
::examples::rmi_iiop::ejb::rmi_iiop::TradeResult_ptr result;
cout << "Buying 3000 shares of BEAS" << endl;
result = trader->buy(BEASsym, 3000);
 . . .

The "buy" request from the CORBA client is for 3000 shares of BEA stock with symbol BEAS. The actual number of shares traded is 500, imposed by the tradeLimit threshold defined in the ejb-jar.xml deployment file for the WebLogic Server examples.

Listing 2-3 tradeLimit Defined in ejb-jar.xml

 . . .
<env-entry-name>tradeLimit</env-entry-name> 
<env-entry-type>java.lang.Integer</env-entry-type>
<env-entry-value>500</env-entry-value>
 . . . 

To achieve different results when you run the WLStrader Value Type sample application, you can vary definitions in the ejb-jar.xml file, or constants in the tuxclient.cpp source file.

Building and Running the WLStrader Value Type Sample Application

This section leads you through the process of building and running the WLStrader Value Type sample application.

Before running the example, described later in the sequence of steps, you must obtain the WebLogic Server Inter-operable Object Reference (IOR) by running the host2ior utility. Complete this step once for any WebLogic Server installation. You can obtain this file any time after installing WebLogic Server, and before running an application requiring the file.

Set the Development Environment

When developing in Java, make sure you have a controlled development environment.

Copy the BEA Tuxedo WLStrader Value Type Files

Rename the build command script, and copy the BEA Tuxedo WLStrader Value Type files from the BEA Tuxedo CORBA samples directory to your WebLogic Server examples build area.

Build the Example

Execute the renamed build script for this example. This is the file you renamed before copying from the BEA Tuxedo samples\corba\wlstrader directory into the samples\examples\rmi_iiop\ejb\rmi_iiop directory of your WebLogic Server installation. The script performs the following steps presented here for a Windows environment:

Configure the Server

Start the WebLogic Server by reviewing and implementing the steps defined in the WebLogic Server Examples documentation. See Starting WebLogic Server with the Examples Configuration. Review the configuration file containing the configuration attributes for all of the examples, located in config\examples\config.xml in the WebLogic Server installation location. To run a start server script:

Windows

prompt> startExampleServer

Alternatively, on Windows platforms you can start the WebLogic Server with the examples configuration from the Windows Start Menu.

UNIX

$ sh startExamplesServer.sh

Run the Example

Run the WLStrader Value Type sample program by setting up the environment and starting the tuxclient.exe executable program. The following steps are for a Windows environment:

Additional Sources of Information

The process of developing a BEA Tuxedo CORBA client application to interact with a WebLogic Server application begins with an EJB. If you are creating a new WebLogic Server application, the first step is to design and implement the server.

The following sections list sources of information about the steps required to implement connectivity between an RMI over IIOP CORBA Client and an EJB in WebLogic Server.

WebLogic Server

These topics are included in the WebLogic Server online documentation:

Object Management Group (OMG)

BEA Tuxedo CORBA

The BEA Tuxedo online documentation provides complete documentation on CORBA topics in the BEA Tuxedo product. The references listed here contain information on creating CORBA clients, the COSNaming Service, the IDL command, and BEA Tuxedo support for value types: