Let's say you have an application that needs to make a connection to a database, such as a mySQL database. In WebSphere, you can create a JDBC data source that points to the mySQL database. Check out my article Create JDBC data source in WebSphere. In this example, the JDBC data source has JNDI "jdbc/mySQL".

Optionally, you could also create the J2C authentication alias in WebSphere. The J2C authentication alias would contain the username and password used to connect to the mySQL database. Check out my article JDBC data source and J2C alias in WebSphere.

In WEB-INF/web.xml file of your Java applications WAR, you would define the resource reference.

• res-ref-name should be an exact match of the data source JNDI in WebSphere
• res-type must be javax.sql.DataSource

<resource-ref>
  <res-ref-name>jdbc/mySQL</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
</resource-ref>

In WEB-INF/ibm-web-bnd.xml of your Java applications WAR.

• binding-name should be an exact match of res-ref-name
• name should be an exact match of the data source name in WebSphere
• authentication-alias is optional - if used, name should be an exact match of the name of the J2C authentication alias in WebSphere

<?xml version="1.0" encoding="UTF-8"?>
<web-bnd 
	xmlns="http://websphere.ibm.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://websphere.ibm.com/xml/ns/javaee http://websphere.ibm.com/xml/ns/javaee/ibm-web-bnd_1_0.xsd"
	version="1.0">

    <resource-ref binding-name="jdbc/mySQL" name="jdbc/mySQL">
      <authentication-alias name="mysql_userid_password"/>
    </resource-ref>

</web-bnd>

Now when deploying your application to WebSphere, the application will be set to use the JDBC data source and J2C authentication alias so that the application can connect to the mySQL database.