The cmt
quickstart demonstrates Container-Managed Transactions (CMT), showing how to use transactions managed by the container.
What is it?
The cmt
quickstart demonstrates how to use container-managed transactions (CMT), which are transactions managed by the container in Red Hat JBoss Enterprise Application Platform. It is a fairly typical scenario of updating a database and sending a JMS message in the same transaction. A simple MDB is provided that prints out the message sent but this is not a transactional MDB and is purely provided for debugging purposes.
Aspects touched upon in the code:
-
XA transaction control using the container managed transaction annotations
-
XA access to the standard default datasource using the JPA API
-
XA access to a JMS queue
After you complete this quickstart, you are invited to run through the following quickstarts:
-
jts - The
jts
quickstart builds upon this quickstart by distributing theCustomerManager
andInvoiceManager
. -
jts-distributed-crash-rec - The crash recovery quickstart builds upon the jts quickstart by demonstrating the fault tolerance of JBoss EAP.
What are Container Managed Transactions?
Prior to EJB, getting the right incantation to ensure sound transactional operation of the business logic was a highly specialized skill. Although this still holds true to a great extent, EJB has provided a series of improvements to allow simplified transaction demarcation notation that is therefore easier to read and test.
With CMT, the EJB container sets the boundaries of a transaction. This differs from BMT (bean-managed transactions), where the developer is responsible for initiating and completing a transaction using the begin
, commit
, and rollback
methods on a javax.transaction.UserTransaction
.
What Makes This an Example of Container Managed Transactions?
Take a look at org.jboss.as.quickstarts.cmt.ejb.CustomerManagerEJB
. You can see that this stateless session bean has been marked up with the @javax.ejb.TransactionAttribute
annotation.
The following options are available for this annotation.
- Required
-
As demonstrated in the quickstart. If a transaction does not already exist, this will initiate a transaction and complete it for you, otherwise the business logic will be integrated into the existing transaction.
- RequiresNew
-
If there is already a transaction running, it will be suspended, the work performed within a new transaction which is completed at exit of the method and then the original transaction resumed.
- Mandatory
-
If there is no transaction running, calling a business method with this annotation will result in an error.
- NotSupported
-
If there is a transaction running, it will be suspended and no transaction will be initiated for this business method.
- Supports
-
This will run the method within a transaction if a transaction exists, alternatively, if there is no transaction running, the method will not be executed within the scope of a transaction.
- Never
-
If the client has a transaction running and does not suspend it but calls a method annotated with Never then an EJB exception will be raised.
Considerations for Use in a Production Environment
- H2 Database
-
This quickstart uses the H2 database included with Red Hat JBoss Enterprise Application Platform 7.1. 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.
System Requirements
The application this project produces is designed to be run on Red Hat JBoss Enterprise Application Platform 7.1 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 EAP_HOME
In the following instructions, replace EAP_HOME
with the actual path to your JBoss EAP installation. The installation path is described in detail here: Use of EAP_HOME and JBOSS_HOME Variables.
Start the JBoss EAP Standalone Server
-
Open a terminal and navigate to the root of the JBoss EAP directory.
-
Start the JBoss EAP server with the full profile by typing the following command.
$ EAP_HOME/bin/standalone.sh -c standalone-full.xml
NoteFor Windows, use the EAP_HOME\bin\standalone.bat
script.
Build and Deploy the Quickstart
-
Make sure you start the JBoss EAP server as described above.
-
Open a terminal and navigate to the root directory of this quickstart.
-
Type the following command to build the artifacts.
$ mvn clean package wildfly:deploy
This deploys the cmt/target/cmt.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/cmt/
You are presented with a simple form for adding customers to a database.
After a customer is successfully added to the database, a message is produced containing the details of the customer. An example MDB dequeues this message and print the following contents.
Received Message: Created invoice for customer named: Jack
If an existing customer name is provided, no JMS message is sent. Instead of the above message, a duplicate warning is displayed.
The customer name should match: letter & '-', otherwise an error is given. This is to show that a LogMessage
entity is still stored in the database. That is because the logCreateCustomer
method in the LogMessageManagerEJB
EJB is decorated with the @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
annotation.
Server Log: Expected Warnings and Errors
You will see the following warnings in the server log. You can ignore these warnings.
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.
-
Make sure you start the JBoss EAP server as described above.
-
Open a terminal and navigate to the root directory of this quickstart.
-
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 JBoss EAP server, and build and deploy a quickstart, see Use JBoss Developer Studio or Eclipse to Run the Quickstarts.
Note
|
Within JBoss Developer Studio, make sure you define a server runtime environment that uses the standalone-full.xml configuration file.
|
Deploy the Quickstart to OpenShift Online
Use these instructions to deploy the quickstart to Red Hat OpenShift Online. If you do not yet have an OpenShift Online account and are interested in signing up for one, see Choose a Plan in the OpenShift Online documentation located on the Red Hat Customer Portal. For information about running JBoss EAP on Red Hat OpenShift Online, see Getting Started with JBoss EAP for OpenShift Online, also located on the Red Hat Customer Portal.
Create and Deploy the Quickstart Project
Follow these instructions to deploy this quickstart to OpenShift Online.
-
Browse to OpenShift Online console and login with your credentials.
-
On the View All Projects or Welcome to Project page, click Create Project.
-
On the Create Project page, enter the following information:
Name: cmt Display Name cmt Description: cmt
-
Click Create to create the project.
-
On the My Projects page, choose your new cmt and click Browse Catalog.
-
Choose JBoss EAP CD (no https) and then click Next to view the Information page.
-
Click Next to navigate to the Configuration page. . . Enter the following information. You can leave the remaining fields as they are.
Add to Project: cmt Application Name: cmt Custom http Route Hostname: (leave blank) Git Repository URL: https://github.com/jboss-developer/jboss-eap-quickstarts/ Git Reference: openshift Context directory: cmt
-
Click the Create button.
-
Click on the Continue to the project overview link.
-
You should see "Build #1 is running …" with the console log below.
Cloning ... Downloading ... Building ... Copying ... Pushing ...
-
At the end of the build, you should see "Push successful".
-
Click View Full Log to see the entire log.
-
-
Click the Overview tab to see the
cmt
deployment. -
Click on the application URL on the right side of the page to view the running application. It should be in the following pattern:
http://APPLICATION_NAME-PROJECT_NAME.PORT.HOST.openshiftapps.com
Delete the Quickstart Project
Follow these instructions to delete the project from OpenShift Online.
-
Go to the View All Projects page and select Delete Project from the drop down list to the right of the cmt project.
-
Type the name of the project to confirm, and then click Delete
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