Extend DB2 data source definitions at the application level

Extend data source definitions, which consist of non-core or custom properties, for DB2® data sources to add a greater level of application flexibility when you are using the DB2 Universal JDBC driver or DB2 Using IBM® JCC driver. This capability is sometimes referred to as heterogeneous pooling. Use this feature to configure a DB2 data source in the application server with a core set of data source properties, and defer to individual applications to define any custom or non-core properties, like currentSchema or clientApplicationInformation, that you want to be application specific. You can also use these extended definitions to override any non-core or custom properties that are already defined for the data source. In addition, this feature can reduce the number of physical connections that the application server uses by employing one connection pool between resources that connect to the same data source.

1. Update the data source definitions for an application that is already installed.
   1. Navigate to the panel to manage the resource references for the application.
      • For applications that do not use container-managed persistence, click Applications > WebSphere enterprise applications > application_name > Resource references.
      • For applications that use container-managed persistence, click Applications > WebSphere enterprise applications > application_name > Provide default data source mapping for modules containing 2.x entity beans. You cannot add extended properties for individual CMP beans.
      • You can configure two resource reference files on the same data source. This allows you to extend the custom properties on the data source to include two different schema names (currentSQLId on z/OS® or currentSchema name in the custom properties) that can be used to exploit the capabilities of the application server. See the topic Configure two resource reference files on the same data source for more information.
        Note: For IBM Optim™ PureQuery Runtime, if this is an XA data source you must define a new custom property on the data source where property_name = downgradeHoldCursorsUnderXa and boolean value = true.
   2. Navigate to the panel for extended data source properties.
      Select a resource from the table and click Extended properties... in the panel before the table rows. If the data source does not support extended data source properties, you will receive an error when you try to apply these changes.
   3. Add one or more extended data source custom properties that are specific to that target resource.
      Click New, and complete the required fields. Repeat this step for each property for which you want to extend the data source. When finished, click OK to return to the previous screen. You cannot modify the following data source properties, which must be the same for all applications that use this data source:

      • accountingInterval
      • dataSourceName
      • databaseName
      • kerberosServerPrincipal
      • loginTimeout
      • logWriter
      • password
      • pkList
      • planName
      • portNumber
      • readOnly
      • securityMechanism
      • serverName
      • user
   4. Optional: Configure two res-refs and the isolation level in the ibm-ejb-jar-ext.xml
2. Create data source definitions for an application during installation.
   1. Navigate to the panel to map the resource references for the application. Select the install step Map resource references to resources and follow steps b and c from step 1 that describe how to update the data source definitions for an application that is already installed.
3. Optional: To avoid two-phase commit transactions, employ the get/use/close connection pattern.
   The get/use/close pattern is when an application gets a connection from a data source or connection factory and completes the current work within a single method, and the application does not call another method until that work is complete.
   1. Ensure that your applications use the get/use/close connection pattern.
   2. Enable the application server to verify use of the get/use/close connection pattern in applications, which will lead to the avoidance of two-phase commit processing if the sharing leads to one and only one physical connection being used.
      1. Click Resources > JDBC > Data sources > data_source > WebSphere Application Server data source properties
      2. Select Optimize for get/use/close connection pattern with heterogenous pooling. You will receive error messages if you select this option and your applications do not use the get/use/close connection pattern.
4. Optional: Heterogeneous pooling is enabled by default. Under certain circumstances it might be desirable to disable heterogeneous pooling for a data source. A data source custom property can be defined to deactivate this pooling support. The data source custom property is called, enableHeterogeneousPooling. If enableHeterogeneousPooling is not defined for a data source or if this property exists for a data source and has the value true, then heterogeneous pooling is enabled. If enableHeterogeneousPooling is defined for a data source and has the value false, then heterogeneous pooling is disabled. To define enableHeterogeneousPooling for a data source and disable heterogeneous pooling, perform the following steps:
   1. Click Resources > JDBC provider > JDBC_provider
   2. Under additional properties, click Data sources.
   3. Click the name of the data source.
   4. Create the enableHeterogeneousPooling custom property.
      1. Click New.
      2. Enter enableHeterogeneousPooling for the name field.
      3. Enter false in the value field to specifies that you want to disable heterogeneous pooling.
   5. Click Apply then Save.