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Integrating BTM with iBatis

iBatis can be integrated straight with any JTA transaction manager. These instructions have been verified against BTM 1.2.

Contents

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JTA datasources

iBatis cannot directly create a BTM PoolingDataSource. You will have to create them yourself (either via the API or the Resource Loader) and make sure they are bound to a JNDI server.

Setting up a JNDI server

You have to bind the datasources to some JNDI server. You can use any one you wish, including the one embedded in your application server.

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This will configure Tomcat's JNDI server as the default implementation. It is a simple intra-VM server that implements the most important JNDI features. You can now just create a InitialContext with the no-args constructor to have access to it.

API way: Creating the datasources

As you can expect, you will need to create one PoolingDataSource per database. Say that you want to use two Embedded Derby databases, and configure them via the BTM API. Here is what your code would look like:

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Code Block
Context ctx = new InitialContext();
ctx.createSubcontext("jdbc");
ctx.rebind("jdbc/testDS1", ds1);
ctx.rebind("jdbc/testDS2", ds2);
ctx.close();

Resource Loader way: Creating the datasources

You can use BTM's Resource Loader instead of the BTM API. It is usually a good idea when you want to create a fully standalone application as you can get rid of the datasources creation, JNDI binding and shutdown code.

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This has the exact same behavior as creating the PoolingDataSource objects and binding them to JNDI yourself. It is just more convenient.

iBatis SqlMapClients

You need to configure exactly one SqlMapClient per datasource.

Datasource JNDI location

You have to tell iBatis where to get the BTM datasource via JNDI. Add a DataSource property to the dataSource tag and set its value to the JNDI location of your datasource:

Code Block
xml
xml
<dataSource type="JNDI">
  <property name="DataSource" value="jdbc/testDS1"/>
</dataSource>

Transaction Manager JNDI location

You have to set transactionManager tag's type attribute to JTA and wrap the dataSource tag in it.

Code Block
xml
xml
  <transactionManager type="JTA" >
    <property name="UserTransaction" value="UserTransaction"/>
    <dataSource type="JNDI">
      <property name="DataSource" value="jdbc/testDS1"/>
    </dataSource>
  </transactionManager>

SqlMapConfig XML configuration files

Here is what the SqlMapConfig1.xml file will look like for the first datasource.

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Code Block
XML
XML
<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE sqlMapConfig      
    PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN"      
    "http://ibatis.apache.org/dtd/sql-map-config-2.dtd">

<sqlMapConfig>

  <transactionManager type="JTA" >
    <property name="UserTransaction" value="UserTransaction"/>
    <dataSource type="JNDI">
      <property name="DataSource" value="jdbc/testDS2"/>
    </dataSource>
  </transactionManager>
  
  <sqlMap resource="bitronix/examples/ibatis/entities/User.xml"/>

</sqlMapConfig>

End result

Now that iBatis and BTM are properly configured, you can simply use the JTA and iBatis APIs in your application.

Application code

Here is what your code will look like when you want to update the content of both databases atomically:

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Say that persistUser() creates a new user, in no way will a user be created in one database and not in the other.

Download

You can download a sample runnable application putting these explanations in practice. It contains all the code that has been skipped for clarity in this page. Both the API and Resource Loader ways are implemented so you can try both and see which one you prefer.

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