Using Transactional Scope in JMS to Database

Understand the concept of transactional scope and rollback error handling strategy.

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Description

Mule applies the concept of transactions to operations in application for which the result cannot remain indeterminate. This example illustrates the concept of transactional scope and rollback error handling strategy in a use case where data is sent from JMS to a MySQL DB.

Example Use Case

In this example the JMS endpoint listens for XML messages sent to the "in" queue. This message is logged and then inserted to a MySQL database. After the order has been inserted an error is thrown using a Java component. This error is handled using the rollback exception handling strategy which redelivers the message for a set number of times before it logs an error message. As the database connector is within the transactional scope, the action that inserted the order is rescinded.

Set up and run the example

Import the example project into your workspace
Start activeMQ server as well as the MySQL server and establish a connection to the database
Run the import.sql script placed under scr/main/resources to create a MySQL table
Run the Example project as a mule application
Go to the activemq web admin console at http://localhost:8161/admin/send.jsp and send the following message to the queue named in:
```
 <order>
 <itemId>1</itemId>
 <itemUnits>2</itemUnits>
 <customerId>1</customerId>
 </order>
```

Go to the console in Anypoint studio and see the following log:

 "Message with id "ID:Lenovo-PC-49554-1404281777345-3:1:1:1:65" has been redelivered 3 times on endpoint "jms://in", which exceeds the maxRedelivery setting of 2 on the connector "Active_MQ". Message payload is of type: ActiveMQTextMessage (org.mule.transport.jms.redelivery.MessageRedeliveredException)

The error occurs after SQL insert but if you look at the content of orders table in your DB using MySQL workbench you see that no record was inserted. This is because DB and JMS operations are in the transactional scope.

Documentation

Read full documentation in GitHub

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