How to lookup JNDI resources on WebLogic?

I deployed a legacy application on WebLogic 11g. The application has the following code:

 Context context = new InitialContext();
 dataSource = (javax.sql.DataSource) context.lookup("java:myDataSource");

I also have a data source configured in WebLogic with the JNDI name of:

     jdbc/myDataSource

When the above java code runs, I get the following exception:

       javax.naming.NameNotFoundException: While trying to look up /myDataSource in /app/webapp/axis2.war/60105275.; remaining name '/myDataSource'
        at weblogic.jndi.internal.BasicNamingNode.newNameNotFoundException(BasicNamingNode.java:1139)

      at weblogic.jndi.internal.ApplicationNamingNode.lookup(ApplicationNamingNode.java:144)

I'm fairly new to JNDI, so my question is? Where is the disconnect in naming? What does it mean when a context lookup has a prefix of "java:" ?

Thanks!