5 Replies Latest reply on Aug 11, 2004 4:45 PM by Roberto Lucignani

    Retrive datasource from remote VMs

    Roberto Lucignani Newbie

      I have the following problem:

      I have two servers, one runs JBoss 3.2.5 and one Tomcat 4.1.30.

      I configured the datasource in JBoss copying the oracle-ds.xml into the deploy directory and adapting it to my oracle instance.
      The drivers (classes12.zip) are in the lib directory.

      Now, I want to get a datasource from the tomcat machine via JNDI

       try {
       Properties pf = new Properties();
       File jndiPF = new File("jndi.properties");
       InputStream is = (InputStream)new FileInputStream(jndiPF);
       System.out.println("Property file loaded");
       System.out.println("Working on: " + pf.getProperty("java.naming.provider.url"));
       Context ctx = new InitialContext(pf);
       System.out.println("Context created");
       NamingEnumeration ne = ctx.list("java:" + args[0]);
       while (ne.hasMore()) {
       Object el = ne.next();
       System.out.println(" - " + el.toString());
       DataSource ds = (DataSource)ctx.lookup("java:/jdbc/OracleDS");
       System.out.println("Datasource retrived");
       } catch (Exception e) {
       System.out.println("Error: " + e.getMessage());

      the jndi.properties file is the following

      #The jnp socket factory class
      #The TimedSocketFacory connection time out in milliseconds (0 == blocking)
      #The TimedSocketFactory read timeout in milliseconds (0 == blocking)

      the loop on the initial context (java:/) show the following entries:

      - HAILConnectionFactory: javax.naming.LinkRef
      - jmx: org.jnp.interfaces.NamingContext
      - HTTPXAConnectionFactory: org.jboss.mq.SpyXAConnectionFactory
      - ConnectionFactory: org.jboss.mq.SpyConnectionFactory
      - UserTransactionSessionFactory: $Proxy12
      - HTTPConnectionFactory: org.jboss.mq.SpyConnectionFactory
      - XAConnectionFactory: org.jboss.mq.SpyXAConnectionFactory
      - invokers: org.jnp.interfaces.NamingContext
      - UserTransaction: org.jboss.tm.usertx.client.ClientUserTransaction
      - UILXAConnectionFactory: javax.naming.LinkRef
      - HAILXAConnectionFactory: javax.naming.LinkRef
      - UIL2XAConnectionFactory: javax.naming.LinkRef
      - queue: org.jnp.interfaces.NamingContext
      - topic: org.jnp.interfaces.NamingContext
      - console: org.jnp.interfaces.NamingContext
      - UIL2ConnectionFactory: javax.naming.LinkRef
      - UILConnectionFactory: javax.naming.LinkRef
      - UUIDKeyGeneratorFactory: org.jboss.ejb.plugins.keygenerator.uuid.UUIDKeyGeneratorFactory

      but when I try to get the datasource I configured it says:

      jdbc not bound

      Looking in the FAQs (Creating a JDBC datasource) I found this phrase:

      . . . DataSource wrappers are bound under the java:/ prefix since they are not usable outside of the server VM.

      so if the JNDI datasources are available only if my code is running in the same VM I have to work only with the embedded version of tomcat ? why have I to specify a provider URL if it work only on the same host ? I'm missing something ?

      How can I configure a pool available via JNDI from remote VMs ?

      thanks in advance

        • 1. Re: Retrive datasource from remote VMs
          Darran Lofthouse Master

          why have I to specify a provider URL - JNDI can be used remotely, it is only access to items bound under the java: namespace that can't be used remotely.

          I think I remember reading something on here that said that access to datasources remotely was being added to a later verion of JBoss. (Possibly the 4.0 branch).

          • 2. Re: Retrive datasource from remote VMs
            Roberto Lucignani Newbie

            This is a great problem for me, I can't scale EJBcontainers and Servlet containers on multiple hosts in this way.

            I think I have to choose another EJB container, I can't wait version 4, unfortunately :(


            • 3. Re: Retrive datasource from remote VMs
              Adrian Brock Master

              You want to stop and think about what you are doing before
              you start configuring such an anti-pattern.
              I can't belive people still do this. Just because something
              is technically possible, doesn't mean you should do it.

              Why serialize everything between the servlet and ejb container?
              This has been discussed so many times before...

              All I can say is we don't license by the number of cpus the ejb
              container is deployed on (a major consideration when using
              other containers where this is the case), there is no need to
              minimize the ejb container machines.
              This is usually the real reason people advocate separating servlet
              and ejb constainers.

              Pool available via jndi
              Ridiculous. Let's create a pool to efficiently use resources,
              but then use each connection from the pool remotely, negating
              any benefit. The connections will also be held for longer
              (network latency) and you have to trust the client to use the
              connection efficiently (i.e. not to hog the resources).

              Create the pool where it is used, i.e. in the servlet container.

              The only reason not to colocate is because you want the servlet
              container in the demilitarised zone.
              If that is true, why have you punctured a hole straight through
              to your db? And why do you have business logic inside the servlet
              in the demilitarized zone anyway?

              • 4. Re: Retrive datasource from remote VMs
                Roberto Lucignani Newbie

                first of all, thank you for your quick reply
                you are right about the pool available via jndi, and I know that, but the problem is that I have to integrate systems from different providers that have no enough skills to rebuild things in the right way now.

                I'll configure JNDI locally on every servlet container. I hope to re-colocate all the pieces in the right place in a second time

                Thanks again

                • 5. Re: Retrive datasource from remote VMs
                  Roberto Lucignani Newbie

                  about the demilitarised zone, the servlet containers and the EJB containers are behind the DMZ.
                  Only the web server is in the DMZ. Communication between the Web server and tomcats is made via jk connector