# bmt: Bean Managed Transactions with JPA and JTA

Mike Musgrove

> The `bmt` quickstart demonstrates Bean-Managed Transactions (BMT), showing how to manually manage transaction demarcation while accessing JPA entities.

## What is it?

The `bmt` quickstart demonstrates how to manually manage transaction demarcation while accessing JPA entities in WildFly Application Server.

On occasion, the application developer requires finer grained control over the lifecycle of JTA transactions and JPA Entity Managers than the defaults provided by the Java EE container. This example shows how the developer can override these defaults and take control of aspects of the lifecycle of JPA and transactions.

When you run this example, you are presented with a Use bean managed Entity Managers checkbox.

- If you check the checkbox, it shows the developer responsibilities when injecting an Entity Manager into a managed (stateless) bean.

- If you uncheck the checkbox, shows the developer responsibilities when using JPA and transactions with an unmanaged component.

This example shows how to transactionally insert key value pairs into the database and demonstrates the requirements on the developer with respect to the JPA Entity Manager.

## Considerations for Use in a Production Environment

H2 Database

  This quickstart uses the H2 database included with WildFly Application Server 13. It is a lightweight, relational example datasource that is used for examples only. It is not robust or scalable, is not supported, and should NOT be used in a production environment.

Datasource Configuration File

  This quickstart uses a `*-ds.xml` datasource configuration file for convenience and ease of database configuration. These files are deprecated in WildFly and should not be used in a production environment. Instead, you should configure the datasource using the Management CLI or Management Console. Datasource configuration is documented in the Configuration Guide.

Performance and Scalability

  A Java EE container is designed with robustness in mind, so you should carefully analyze the scalabiltiy, concurrency, and performance needs of your application before taking advantage of these techniques in your own applications.

## System Requirements

The application this project produces is designed to be run on WildFly Application Server 13 or later.

All you need to build this project is Java 8.0 (Java SDK 1.8) or later and Maven 3.3.1 or later. See Configure Maven to Build and Deploy the Quickstarts to make sure you are configured correctly for testing the quickstarts.

## Use of WILDFLY_HOME

In the following instructions, replace `WILDFLY_HOME` with the actual path to your WildFly installation. The installation path is described in detail here: Use of WILDFLY_HOME and JBOSS_HOME Variables.

## Start the WildFly Standalone Server

1. Open a terminal and navigate to the root of the WildFly directory.

2. Start the WildFly server with the default profile by typing the following command.

       $ WILDFLY_HOME/bin/standalone.sh

   Note | For Windows, use the `WILDFLY_HOME\bin\standalone.bat` script.

## Build and Deploy the Quickstart

1. Make sure you start the WildFly server as described above.

2. Open a terminal and navigate to the root directory of this quickstart.

3. Type the following command to build the artifacts.

       $ mvn clean package wildfly:deploy

This deploys the `bmt/target/bmt.war` to the running instance of the server.

You should see a message in the server log indicating that the archive deployed successfully.

## Access the Application

The application will be running at the following URL: http://localhost:8080/bmt/.

You are presented with a simple form for adding key/value pairs, and a checkbox to indicate whether the updates should be executed using an unmanaged component. Effectively this will run the transaction and JPA updates in the servlet, not session beans. If the box is checked then the updates are executed within a session bean method.

1. To list all pairs leave the Key input field empty.

2. To add or update the value of a key, fill in the Key and Value input fields.

3. Click the Submit button to see the results.

## Server Log: Expected Warnings and Errors

You will see the following warnings in the server log. You can ignore these warnings.

    WFLYJCA0091: -ds.xml file deployments are deprecated. Support may be removed in a future version.

    HHH000431: Unable to determine H2 database version, certain features may not work

## Undeploy the Quickstart

When you are finished testing the quickstart, follow these steps to undeploy the archive.

1. Make sure you start the WildFly server as described above.

2. Open a terminal and navigate to the root directory of this quickstart.

3. Type this command to undeploy the archive:

       $ mvn wildfly:undeploy

## Run the Quickstart in Red Hat JBoss Developer Studio or Eclipse

You can also start the server and deploy the quickstarts or run the Arquillian tests in Red Hat JBoss Developer Studio or from Eclipse using JBoss tools. For general information about how to import a quickstart, add a WildFly server, and build and deploy a quickstart, see Use JBoss Developer Studio or Eclipse to Run the Quickstarts.

## Debug the Application

If you want to debug the source code of any library in the project, run the following command to pull the source into your local repository. The IDE should then detect it.

    $ mvn dependency:sources