Package examples.ejb20.basic.statefulSession

This example is a package that demonstrates an EJB written to the EJB 2.0 specification.

See:

 

Interface Summary

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

 

 

Class Summary

Client	This class illustrates calling a stateful SessionBean and performing the following exercises: Create a Trader Buy some shares using the Trader Sell some shares using the Trader Remove the Trader
TraderBean	TraderBean is a stateful SessionBean.
TradeResult	This class reflects the results of a buy/sell transaction.

 

 

Exception Summary

ProcessingErrorException	This class is used with the examples.ejb20.statefulSession package.

 

Package examples.ejb20.basic.statefulSession Description

This example is a package that demonstrates an EJB written to the EJB 2.0 specification. The example is a stateful session EJB called TraderBean.

The example demonstrates:

• Usage of a session EJB written to the EJB 2.0 specification
• Stateful persistence
• Using application-defined exceptions and utilities
• Client Application

Pre-Built Examples

This EJB 2.0 example is shipped pre-built. However, if you want to re-run this example, you can build it following the instructions in Build the example and then re-run it following the instructions in Run the example.

Client Application

The Client application performs these steps:

1. Contacts the Trader home ("TraderHome") through JNDI to find the EJB
2. Creates a Trader
3. Sells shares of "MSFT"
4. Buys shares of "BEAS"
5. Gets the change in the cash account
   (The EJB does not actually "buy" or "sell"; it simulates the actions of accessing a database)
6. Removes the Trader

The application demonstrates how repeated calls to the same session EJB have a persistent state -- the change in the cash account -- that is maintained across all the calls. Notice that neither the client nor the EJB do anything to maintain that state: the container handles it transparently. All the logic for the cash account is encapsulated in the EJB, unlike the stateless session example, where all persistence is provided by the client.

To get the most out of this example, first read through the source code files to see what is happening.

• Client applications
  Client.java

  Interfaces

  Trader.java

  TraderHome.java

  TradeResult.java

  Deployment

  ejb-jar.xml

  weblogic-ejb-jar.xml

  Exception

  ProcessingErrorException.java

  Server (EJBean)

  TraderBean.java

Start with the XML deployment files ejb-jar.xml and weblogic-ejb-jar.xml to find the general structure of the EJB, which classes are used for the different objects and interfaces, then look at Client.java to see how the application works.

These three sections cover what to do:

1. Build the example
2. Start the Examples server
3. Run the example

Build the example

Set up your development shell as described in Setting up your environment.

We provide a build script for you to build the example:

The build script is build.xml.

Run the build script using the following Java ant command:

prompt> ant

The script will build the example and place the files in the correct locations in your WebLogic Server distribution:

• Client.jar file: in SAMPLES_HOME\server\examples\build\clientclasses
• EJB (in EAR file): in SAMPLES_HOME\domains\examples\applications\ejb20_basic_statefulSession.ear

Running the build script places the EJB in the %applications% directory, where it automatically deploys once the server is started. If you are already running the server and build another EJB, it is automatically placed in this directory and instantly deployed.

Additional information on using the build scripts is found in More About Building Examples.

Start the Examples server

1. Start the Examples server.

Run the example

1. Run the client in a separate command line window. Set up your client as described in Setting up your environment, and then run the client by entering:

     prompt> ant run  

2. You should receive output similar to this:

   Beginning statefulSession.Client... 
   
   Creating trader 
   
   Selling 200 of MSFT 
   200 shares sold at a price of 150.0 
   Buying 250 of BEAS 
   250 shares bought at a price of 100.0 
   Change in Cash Account: $5000.0 
   
   Removing trader 
   
   
   End statefulSession.Client... 
   
   

There's more...

Read more about EJB in BEA WebLogic Server Enterprise Java Beans.