Format of the JNDI name for lookup in DataSource

Question

Hi
a) I have made a datasource in Weblogic 10.3 called SQL and its JNDI name as jdbc/SQLDS.
The driver was BEA'S Type 4 Driver for MS SQL Server
Now I am trying to lookup the datasource through an application. I have used the following
lines of code:
InitialContext context = new InitialContext();
DataSource ds = context.lookup("jdbc/SQLDS");
Connection conn = ds.getConnection();
The Application was a success.
I saw in some articles that you can refer to the datasource by even java:comp/env/jdbc/SQLDS,
instead of just jdbc/SQLDS. I tried both ways and I was able to run the application.
b) Then I made another datasource in Weblogic 10.3 called SQL1 and its JNDI name as jdbc/SQL1.
The driver was MS SQL Server Type 4 Driver for versions 2000, 2005
Now I am trying to lookup the datasource through an application. I have used the following
lines of code:
InitialContext context = new InitialContext();
DataSource ds = context.lookup("jdbc/SQL1");
Connection conn = ds.getConnection();
The Application was a success.
I saw in some articles that you can refer to the datasource by even java:comp/env/jdbc/SQL1,
instead of just jdbc/SQL1. I tried the first way and it didnt work. It gave me a NullPointerException
at the line Connection conn = ds.getConnection();
c)Then I made a 3rd datasource in Weblogic 10.3 called SQL2 and its JNDI name as jdbc/SQL2DS.
The driver was MS SQL Server Type 4 Driver for versions 2000, 2005
Now I am trying to lookup the datasource through an application. I have used the following
lines of code:
InitialContext context = new InitialContext();
DataSource ds = context.lookup("jdbc/SQL2DS");
Connection conn = ds.getConnection();
The Application was a success.
I saw in some articles that you can refer to the datasource by even java:comp/env/jdbc/SQL2DS,
instead of just jdbc/SQL2DS. I tried the first way and it didnt work. Again, it gave me a NullPointerException
at the line Connection conn = ds.getConnection();
I was confused why the 2nd and 3rd way didnt work . Is it becaue I used Microsoft's MS SQL Server Type 4 Driver?
I have added the jar file in the WEBLOGIC_CLASSPATH. Why is it not recognising java:comp/env/jdbc/SQL2DS ?
I would be grateful if somebody could give me ideas on this...
Thanks
Neeti

Answer 1

To use application scoped or indirect JNDI lookups (i.e. java:comp/env/...) you usually need to define a <resource-ref> entry in your deployment descriptor(s). Not sure what type of application you are using to test (web-app, EJB,) but for java:comp/env/ lookups to work, you need to define resource references. The fact that your first test succeeded is somewhat strange. Without the resource reference definitions, I would have expected your JNDI lookups to fail with a NamingException instead of the lookup returning NULL for the datasource.
Assuming you are doing your test from a web-app, you need to add <resource-ref> definitions to your web.xml file similar to the following:
<resource-ref>
<res-ref-name>*jdbc/SQL2DS*</res-ref-name>
<res-type>java.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
and then add <reference-descriptor> definitions to your weblogic.xml file similar to the following:
<reference-descriptor>
<resource-description>
<res-ref-name>*jdbc/SQL2DS*</res-ref-name>
<jndi-name>*jdbc/SQL2DS*</jndi-name>
</resource-description>
</reference-descriptor>
Once you do these steps your lookup("java:comp/env/jdbc/SQL2DS") should function properly from within your web-app.