Samples Index

The SimpleBank BMP Robean Sample Application

The SimpleBank BMP Robean sample application demonstrates how to use Read Only Beans (ROBs). ROBs are entity beans that are never modified by an Enterprise JavaBean (EJB) client. They can be declared by specifying the is-read-only-bean element in the sun-ejb-jar.xml. The data that an ROB represents may be updated by external means. To eliminate the cost of using ejbStore, use ROBs when the data they represent is stable or rarely changes.

ROB restrictions include the following:

• ROBs cannot start their own transactions. Only container transactions are allowed.
• Container will not call ejbStore on ROBs.
• The ejbLoads will be called only when a bean is created or when a transactional method is called or at refresh intervals.
• ROBs Home interface need not have ejbCreate and ejbRemove methods.

An application can refresh the state of ROBs:

• By invoking a transactional method - In the sample, all the methods of CustomerTransactionalEJB are defined as transactional. To refresh the state of CustomerTransactionalEJB, the servlet invokes the getBalance method of CustomerTransactionalEJB, which is transactional.
• At regular intervals, by specifying the refresh-period-in-second property in sun-ejb-jar.xml - If the period specified is negative, the state of ROB will never be refreshed. If the period specified is 0 (zero), the state of ROB will always be refreshed. If the period specified is greater than zero, the state of ROB will be refreshed periodically at that rate. In the sample, CustomerRefreshEJB has a refresh period of 60 seconds, so the state of CustomerRefreshEJB is refreshed every minute.
• Programmatically - The beans that update data used by the ROBs, notify the ROBs to refresh their state. The state of the ROB can be updated with the help of ReadOnlyBeanNotifier. For example, this code updates the state of CustomerProgRefreshEJB:

  ReadOnlyBeanNotifier notifier =
    ReadOnlyBeanHelper.getReadOnlyBeanNotifier("java:comp/env/ejb/customerProgRefresh");
    notifier.refresh(new PKString1(SSN));

Setting Up the Environment

Before you deploy or run the application, you must ensure that a database resource has been configured for Application Server. The included asant deployment script automatically performs this step for you. But if you are using another deployment mechanism, you must perform it manually.

You can use any JDBC-compliant relational database server, but specific instructions are provided for the following:

• Derby: Derby comes with Application Server. For more information, see Using the Derby Database With Sample Applications.
• PointBase: a small-footprint Java relational database. For more information, see Using PointBase With the Samples.
• Oracle: One of the most popular relational databases. For more information, see How to Run Samples With Oracle Database Server.

Building, Deploying, and Running the Application

The general instructions for building, deploying, and running sample applications are provided in Building, Deploying, and Running Sample Applications. In reading this document, use the following application-specific variables for this application:

• install_dir is the directory where Application Server is installed.
• app_dir is the application base directory: install_dir/samples/ejb/bmp/apps/robean.
• appname is the application name: bmp-robean.
• The prebuilt EAR file is bmp-robean.ear.
• context_root is SimpleBank.

Follow this general procedure:

1. Build the Application. The build file, build.xml, is in the app_dir directory, specifically, install_dir/samples/ejb/bmp/apps/robean.
2. Deploy the Application The EAR file is install_dir/samples/ejb/bmp/apps/robean/bmp-robean.ear.
3. Run the Application The context root is SimpleBank.

Resrouce Configuration

This application requires configuration of JDBC resources. If you deploy it using asant, then the script will register the resources automatically. But if you use another deployment mechanism, you must perform it manually as follows:

1. Start the database server if you have not already done so.
2. Configure the JDBC connection pool:

   asadmin create-jdbc-connection-pool --host admin-host --port admin-port
     --user user --password password
     --datasourceclassname datasource-classname
     --property User=bmp:Password=bmp:url-property="JDBC URL"
     bmp-robean-pool
     

   For Derby, use DatabaseName as the value for url-property. You must escape colons (:) and slashes (/) in JDBC URL. An example of JDBC URL is jdbc\:derby\:\/\/localhost\:1527\/DerbyDB;create=true.
3. Configure the JDBC resource:

   asadmin create-jdbc-resource --host admin host --port admin port
   --user user --password password
   --connectionpoolid  "cmpcustomer-pool jdbc/cmpcustomer"
   

Using the Application

1. In the SimpleBank application, enter 123456789 as Customer Social Security Number.
2. Click Enter.
3. Enter amount in $ text box and click Update to update the current balance.
4. Click on Get Trans. Balance. to update Transactional Refresh.
5. Click on Get Prog. Balance. to update Programmatic Refresh.
6. Wait for thirty seconds.
   The page will be refreshed and Time-based Refresh will be updated.

Copyright © 2006 Sun Microsystems, Inc. All rights reserved.