Understanding EJB Data Source Services

A data source is a Java object that represents the physical enterprise information system to which OC4J persists entities. Your application uses a data source object to retrieve a connection to the enterprise information system the data source represents.

This section describes:

What Types of Data Source does OC4J Support?
Where Do You Configure Data Source Information in OC4J?
What is a Default Data Source?
How Does OC4J Handle Multiple Data Sources?

For more information, see:

"Configuring Data Sources"
"Data Sources" in the Oracle Containers for J2EE Services Guide

What Types of Data Source does OC4J Support?

OC4J supports the following types of data source:

Managed: a managed data source is an OC4J-provided implementation of the java.sql.DataSource interface that acts as a wrapper for a JDBC driver or data source.
Native: a native data source is a JDBC vendor-provided implementation of the java.sql.DataSource interface.

Table 2-5 lists the characteristics of these OC4J data sources.

Table 2-5 OC4J Data Source Type Characteristics

Characteristic	Managed	Native
Uses OC4J connection pool?	Yes	No
Connections can participate in global transactions?	Yes	No
Connections wrapped with an OC4J `Connection` proxy?	Yes	No

Where Do You Configure Data Source Information in OC4J?

In OC4J, you configure data source information in a data-sources.xml file.

You can include a data-sources.xml file in your EAR but OC4J does not support multiple data-sources.xml files.

For more information, see:

"How Does OC4J Handle Multiple Data Sources?"
"What is a Default Data Source?"

What is a Default Data Source?

To simplify application configuration, you can define default data sources.

How you define a default data source depends on the type of application you want to access the default data source from:

How Does OC4J Handle Multiple Data Sources?

OC4J does not support multiple data sources within different entities in orion-ejb-jar.xml.

If your application is composed of more than one EAR and each EAR contains a data-sources.xml, then, when you deploy your application, OC4J will use the last entity bean's data-source.xml for all entity beans.

To accomodate this scenario, specify the data source in orion-application.xml or specify a default data source.

For more information, see: