How to access JDBC Resource registered in Sun Java System App Server ?

Question

I want to create a stand-alone JDBC application with Java SE using Swing technologies and JNDI technology. The purpose of using JNDI technology is to avoid change of Java Source Code every time I move the database to different location. This Java application will be used in a standalone PC installed with Windows XP Professional with no LAN / WAN connection. Of course, Internet connection is available with the PC.
I use JavaDB to store the data tables and the location of the database is D:\E-DRIVE\SAPDEV. Tomorrow, if I move this database to C:\SAPDEV or any network drive, I do not want to change the Java Source code. I want to use JNDI which, if I am not wrong, helps developers to avoid manual change of Java source code whenever the database location is changed. Changes have to be made only in the JNDI Name which contains all relevant information about the database in order to get connection no matter where the database SAPDEV is stored; it can be placed under D:\E-DRIVE directory or C:\ directory of the hard disk. To implement my intention, I started developing Java application as per the steps mentioned below:
Step 1:
To proceed, first, I sought the help of Sun Java System Application Server Admin Console. I created JNDI object for Connection Pool using the menu path Common Tasks->Resources->JDBC->Connection Pools.
JNDI Name : ABAPRPY
Resource Type : javax.sql.DataSource
Datasource class : org.apache.derby.jdbc.ClientDataSource
Description : ABAP Program Repository
The Connection Pool creation has options for General, Advanced and Additional Settings tabs and I made all the settings relevant to the database I created in D:\E-DRIVE\SAPDEV.
To confirm whether the above settings are correct, I pressed the Ping push button which is available in the General tab of the connection pool creation screen. The system responded with the message Ping Succeeded.
Step 2:
I created a JDBC Resource using the menu path Common Tasks->Resources->JDBC->JDBC Resources.
JNDI Name : jdbc/SAPDEV
Pool Name : ABAPRPY
Description : Database Connection for SAPDEV database
Status : Enabled
I can see all the above settings recorded in the domain.xml which is placed in the folder
C:\Sun\AppServer\domains\domain1\config
Step 3:
I have made sure that Sun Java System Application Server is up and running in the background with JavaDB server. I created a Java Program making sure the following JAR files are included in the classpath:
appserv-admin.jar
appserv-ee.jar
appserv-rt.jar
javaee.jar
fscontext.jar
Plus, the lib directory of JDK 1.6 & C:\Sun\AppServer\domains\domain1\config
Source code of the program is as follows: I used NetBeans IDE to create my project file.
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.naming.*;
import javax.activation.DataSource;
public class JNDILookup {
public static void main(String[] args) {
try {
InitialContext initCtx = new InitialContext();
DataSource ds = (DataSource) initCtx.lookup("java:comp/env/jdbc/sapdev>");
} catch (NamingException ex) {
Logger.getLogger(JNDILookup.class.getName()).log(Level.SEVERE, null, ex);
When I attempted to compile the above program in NetBeans IDE ,no compilation error reported. But while executing the program, I got the following run-time error message:
SEVERE: null
javax.naming.NameNotFoundException: No object bound for java:comp/env/jdbc/sapdev> [Root exception is java.lang.NullPointerException]
at com.sun.enterprise.naming.java.javaURLContext.lookup(javaURLContext.java:224)
at com.sun.enterprise.naming.SerialContext.lookup(SerialContext.java:396)
at javax.naming.InitialContext.lookup(InitialContext.java:392)
at SAPConnect.JNDILookup.main(JNDILookup.java:21)
Caused by: java.lang.NullPointerException
at com.sun.enterprise.naming.java.javaURLContext.lookup(javaURLContext.java:173)
... 3 more
Now, I want to come out of this situation; at the same time, I want to preserve the settings I have made in the Sun Java System Application Server Admin Console. That is, I want to programmatically access the data source using Connection Pool created in Sun Java System Application Server Admin Console.
I request dear forum members to provide me an appropriate solution.
Thanks and regards,
K. Rangarajan.

Answer 1

jay44 wrote:
Bare in mind I am attempting the context.lookup() from inside the container (my code is in a session bean). I have accessed the server and have my bean "say hello" first to verify the bean works OK, then I call a method with this rather standard code:
String jndiDataSourceName ="Second_EJB_Module_DataBase";
Logger.getLogger(DynamicPU.class.getName()).log(Level.INFO,"Programatically acquiring JNDI DataDource: "+ jndiDataSourceName);
InitialContext ctx;
try {
ctx = new InitialContext();
ds =(DataSource)ctx.lookup("java:comp/env/jdbc/"+jndiDataSourceName);
} catch (NamingException ex) {
Logger.getLogger(DynamicPU.class.getName()).log(Level.SEVERE, null, ex);
return "Exception generated trying to preform JDBC DataSource lookup. \n"+ex.toString();
But when I run the code the server log shows the initial context is created Ok, but an exception is thrown becasue the resource name is not found:
(and i have tried vriations of ctx.lookup("jdbc/"+jndiDataSourceName) etc etc
You are fine here. It works in container because the InitialContext properties have been supplied already. That was the link I forwarded earlier. The InitialContext you create locally needs to locate the container JNDI. That is what the properties specify.
Where I am confused is where you indicate the stack below is from the server log. So, you initiate a standalone (java main method) application, create an InitialContext, and you see the results in your app server log?
LDR5010: All ejb(s) of [EJB_Module_1] loaded successfully!
Programatically acquiring JNDI DataDource: Second_EJB_Module_DataBase
The log message is null.
javax.naming.NameNotFoundException: Second_EJB_Module_DataBase not found
at com.sun.enterprise.naming.TransientContext.doLookup(TransientContext.java:216)
at com.sun.enterprise.naming.TransientContext.lookup(TransientContext.java:188)
at com.sun.enterprise.naming.TransientContext.lookup(TransientContext.java:192)...
at com.sun.corba.ee.impl.orbutil.threadpool.ThreadPoolImpl$WorkerThread.run(ThreadPoolImpl.java:555)
This is strange since I can see this resource (a JDBC connection named Second_EJB_Module_DataBase) is configured on the server from the server's admin console.
That is why you can obtain a lookup from within the container (app server).
For this lookup to work it may be that one must map the name inside an ejb-jar.xml deployed with the application, but I have also read some resources like jdbc connection should have a default name. Does anyone know if my lookup() should work without using an ejb-jar.xml mfile to explcitly map the reource for my application?
Both EBJ's and data sources can be referenced via JNDI. It's a remote lookup (that is normally optimized if it is running in the same JVM). You should not have any dependencies on a JDBC data source being set-up on ejb-jar.xml. That file can of course impact your EJB's. However, data sources are normally set-up on a container-specific basis (e.g., you probably did it through a console, but there is a spec somewhere about how to set up a data source via a resource the app server looks for; it varies from app server to app server). However, once you have that container-specific data source set-up, JNDI operates vendor-neutral. You should be able to take the code above and move it to JBoss or Weblogic or Tomcat or whatever (this is an ideal, in practice, the vendors sometimes put a data source in a name you would not expect, but again, you can use their JMX console to see what the JNDI name is).
(As I stated above if I have to use a deployment discriptor to get at this JNDI datasource, then solution is not "programmatic" as newly configured datasources could not be accessed without redeploying the entire application).
As JSchell alluded to, you will always have at least something vendor-specific. JNDI itself (the code you wrote) is totally portable. However, you have to set the various JNDI environment properties to a given vendor's spec. Ideally, you should not need a vendor's actual InitialContext application, but it's a possibility. Once you can safely cast to Context, you should be vendor-neutral (if not, demand your money back).
So that is exactly where I am stuck, trying to get the lookup to work and wondering if it should work without and xml file mapping the resource for my app.
What we ended up doing for standalone was to provide our own JNDI. If you look at the open source project JOTM, there are examples on how to use that with XBean (if integrating with Spring, as we did), you can easily set up a data source that runs standalone exactly as you get in the container. Another benefit is you get full JTA/JTS support and the ability to run XA transactions. (This might all be alphabet soup, but the app server gives it to you, and this is the way we ended up doing the same: JNDI + JTA + JTS + XA). It ends up the same application code uses a "vanilla" InitialContext and all we have to do is write one or two xml files (one for our app server, a couple for JOTM), and our actual code works the same.
I still think you have a shot at getting to the container's JNDI, just not using their full-blown app server JAR.
I think there must be a simple way to do this with an ejb-jar.xml, I am no expert in JNDI, I could be missing something simple, I will keep at it and post an answer here if I come up with it.
Thanks, jayIt is simple to code. Getting it to integrate with your app server, yes, that can be challenging. But it has nothing to do with EJB's. Write a simple test. Using nothing but DataSource and InitialContext. Let us know where you get stuck.
- Saish