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This sample demonstrates the use of the Transaction Mediator using a sample distributed transaction. 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, and the records will be untouched.
Also, see Transaction Mediator.
Prerequisites
Refer For a list of prerequisites, refer to Prerequisites section in ESB Samples Setupsamples setup page.
Building the
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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_267.xml as shown below:
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<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>
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2. Create two The above sample configuration uses two data sources and database instances to point to the sample databases created according to the synapse configuration defined above. You have to manually create these in your environment for the sample to work.
- For information on creating database instances, refer to Database Instances. Refer the Sample Setup Guide to see how you can set up the derby database server.
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- For information on creating the two sample XA data sources, refer to section Data Sources.
43. Start the ESB with the synapse configuration numbered 267, by running the following command.
wso2esb-samples.sh -sn 267wso2esb-samples.bat -sn 267
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.
6server and log into its management console UI (https://localhost:9443/carbon). In the management console, navigate to Main Menu, click Service Bus and then Source View. Next, copy and paste the above synapse configuration, which helps you explore the example scenario, to the source view
4. Deploy the back-end service SimpleStockQuoteService, and start the Axis2 server using the instructions given in section Starting Sample Back-End Services.
| Info | ||
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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 You now have a running ESB instance, databases and a back-end service deployed in your environment.
Executing the
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sample
We run this setup using the sample Stock Quote Client, which can operate in several modes. For instructions information on this sample client, refer to section Stock Quote Client.
Execute the following ant command to invoke the sample client.
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ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=SUN/ |
In this sample, You can try deleting a record is delete from one database and added adding 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.
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Simulate a failure scenario and notice how all operations roll back, and none of the records gets affected.