JDBC pools configuration
BTM XA datasources can be created via some java code or via a BTM-specific tool called the Resource Loader. You are free to choose the method you prefer, there is absolutely no difference between them.
Using the BTM API
BTM comes bundled with a JDBC XA connection pool which is very easy to configure. You basically have to create an instance of bitronix.tm.resource.jdbc.PoolingDataSource set some properties and you're done.
Here is an example of datasource creation that connects to an Oracle database:
1. The Bitronix
PoolingDataSource is a javabean that implements
2. You have to specify the driver's
XADataSource implementation here.
3. Each datasource must be assigned a unique name. This is required for distributed crash recovery.
4. This datasource can contain at least 0 connection. 0 is the default value when unspecified.
5. This datasource can contain at most 5 connections.
6. If there aren't enough connections in the pool to fulfill a request, new connections will be created, by increments of 1 at a time.
7. You have to set
allowLocalTransactions to true if you want to be able to run SQL statements outside of XA transactions scope. Defaults to false.
8. When specified, this query will be executed to check that the connection is still valid before handing it to the application code.
useTmJoin to false if the vendor's
XADataSource implementation does not implement
XAResource.isSameRM() properly. Refer to the JdbcXaSupportEvaluation page to see if your database needs it. Defaults to true.
deferConnectionRelease to false if the vendor's
XADataSource implementation supports transactions interleaving. Refer to the JdbcXaSupportEvaluation page to see if your database supports it. Defaults to true.
automaticEnlistingEnabled to false if you do not want the
PoolingDataSource to automatically enlist/delist the connections into the XA transactions. You then have to enlist
XAResource objects manually into the
Transaction objects for them to participate in XA transactions. Defaults to true.
12. The amount of seconds the pool will block when a connection is requested but the pool is empty and cannot grow anymore. Defaults to 30.
13. The amount of seconds the pool will wait when a connection has been tested invalid before trying to acquire a new one. Defaults to 1.
14. The amount of prepared statements cached per pooled connection. Defaults to 0, meaning statement caching is disabled.
15. The position of this resource during the 2PC protocol execution. This is required if you want to guarantee that a resource commits before another one. Defaults to 0.
16,17,18. The driverProperties is a
java.util.Properties object. You have to add into it a set of property name / property value of the
OracleXADataSource class. You have to refer to the driver's documentation to know what can / has to be set. The OracleXADataSource javadoc contains this list for the Oracle case. BTM will perform conversion from
boolean or to
int when necessary.
19,20. You can now use the
PoolingDataSource like any other
21. Remember to close the
PoolingDataSource after you're done with it to release the connections.
You do not have to set properties that have a default value. Here is a simplified version of the previous code creating a
PoolingDataSource with minimal settings:
This will create a
PoolingDataSource that will work exactly the same as the previous one. The only difference is that unspecified properties have been left untouched with their default value.
The connection pool will be initialized during the first call to
getConnection(). It might be desirable to initialize the pool eagerly, like during application startup rather than having to wait for the first requests. This can be done by calling
Now line 10 will initialize the pool instead of line 11.
Using the Resource Loader
A datasource configuration utility is also bundled with BTM. It is convenient to use it rather than create your datasources in code. Refer to the Resource Loader page for more details.
Here is the equivalent Resource Loader configuration of the previous code example:
You just have to write those properties in a simple text file and tell BTM where to load it by setting the
resourceConfigurationFilename property of the Configuration object.
Now you also have to know how to get the datasource created by the Resource Loader. There are multiple ways:
- Look up resources using the embedded JNDI provider.
- Another way is to bind a bitronix.tm.resource.ResourceObjectFactory object, passing it a javax.naming.Reference containing a javax.naming.StringRefAddr containing the datasource's
addrTypesomewhere in your JNDI tree. The
bitronix.tm.resource.ResourceObjectFactoryclass will just return the datasource with the specified
uniqueName. This is explained more in-depth in the Tomcat and Jetty integration page.
- The last way is to call bitronix.tm.resource.ResourceRegistrar.get(String uniqueName). This is the least preferred method as this ties your code to BTM which you probably want to avoid.