Sample 657: Distributed Transaction Management

Introduction

This sample demonstrates the use of the Transaction Mediator using a sample distributed transaction.

Prerequisites

Refer to Prerequisites section in ESB Samples Setup page.

Building the Sample

1. First, let's take a look at the synapse configuration for the ESB used for this sample. It is provided in <ESB_HOME>/repository/samples/synapse_sample_657.xml as shown below:

<definitions xmlns="http://ws.apache.org/ns/synapse"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://ws.apache.org/ns/synapse http://synapse.apache.org/ns/2010/04/configuration/synapse_config.xsd">
    <sequence name="myFaultHandler">
        <log level="custom">
            <property name="text" value="** Rollback Transaction**"/>
        </log>
        <transaction action="rollback"/>
        <send/>
    </sequence>
    <sequence name="main" onError="myFaultHandler">
        <in>
            <send>
                <endpoint>
                    <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
                </endpoint>
            </send>
        </in>
        <out>
            <transaction action="new"/>
            <log level="custom">
                <property name="text" value="** Reporting to the Database esbdb**"/>
            </log>
            <dbreport useTransaction="true" xmlns="http://ws.apache.org/ns/synapse">
                <connection>
                    <pool>
                        <dsName>jdbc/XADerbyDS</dsName>
                        <user>synapse</user>
                        <password>synapse</password>
                    </pool>
                </connection>
                <statement>
                    <sql>delete from company where name =?</sql>
                    <parameter expression="//m0:return/m1:symbol/child::text()"
                               xmlns:m0="http://services.samples"
                               xmlns:m1="http://services.samples/xsd"
                               type="VARCHAR"/>
                </statement>
            </dbreport>
            <log level="custom">
                <property name="text" value="** Reporting to the Database esbdb1**"/>
            </log>
            <dbreport useTransaction="true" xmlns="http://ws.apache.org/ns/synapse">
                <connection>
                    <pool>
                        <dsName>jdbc/XADerbyDS1</dsName>
                        <user>synapse</user>
                        <password>synapse</password>
                    </pool>
                </connection>
                <statement>
                    <sql>INSERT into company values ('IBM','c4',12.0)</sql>
                </statement>
            </dbreport>
            <transaction action="commit"/>
            <send/>
        </out>
    </sequence>
</definitions>

2. Create two database instances to point to sample databases created according to the synapse configuration defined above. Refer the Sample Setup Guide to see how you can set up the derby database server.

3. Create two XA data sources in your environment, which the two instances created in step 2 can use. For instructions to create data sources, refer to section Data Sources.

4. Start the ESB with the synapse configuration numbered 657, by running the following command.

wso2esb-samples.sh -sn 657
wso2esb-samples.bat -sn 657

For more information on starting ESB with different synapse configurations, refer to section Starting Sample ESB Configurations.

5. A message should appear in the command or text Linux console stating the server started successfully.

6. Deploy the back-end service SimpleStockQuoteService and start the Axis2 server using the instructions given in section Starting Sample Back-End Services.

Infor

WSO2 ESB comes with a default JTA transaction manager (Atomikos), which allows you to run distributed transactions without deploying the ESB on an external application server.

Now you have a running ESB instance, databases and a back-end service deployed.

Executing the Sample

We run this setup using the sample Stock Quote Client which can operate in several modes. For instructions on this sample client refer to Stock Quote Client.

Execute the following command to invoke the client.

ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=SUN/

In this sample, a record is delete from one database and added to a second database. If either of the operations (deleting from the first database and adding to the other) fails, all operations will roll back. The records will be untouched.