Hi all,
I'd like to ask your opinion about this topic:
I have implemented my JdbcManager as a singleton,
so I have a static instance of the class that
releases a Connection from the pool:

private Connection conn;
static JdbcManager jdbc;

public static JdbcManager getInstance() {

  if (jdbc == null) {
       jdbc = new JdbcManager();
  }

  return jdbc;

}

public void getConnection(String s) {

  try {
  javax.naming.Context ctx = new javax.naming.InitialContext();

  javax.sql.DataSource ds
  = (javax.sql.DataSource) ctx.lookup (s);

  conn = ds.getConnection();

  }
  catch (Exception exc) {
    exc.printStackTrace();
  }

}

(just to make things easier I haven't synchronized the singleton access in getInstance() )

Is this design correct or I cannot apply the Singleton pattern to a class that releases connection from a pool? I'm afraid this will cause a bottleneck in the whole application.
Thanks a lot
Francesco

why not let the container / app server do all the work for u i know jboss , tomcat have connection pooling in them why no just utilize them

As usual, good ideas spawn on it's own from different minds! :)

If I understood the code, as s is the name of a Datasource nothing stop you from use the Container provided Datasource (with pooling, XA support or whatever it has).

I think that the point is to have a Service Locator to encapsulate the process of obtaining the connection from the Datasource. This is a recommended practice by Sun (check http://developer.java.sun.com/developer/restricted/patterns/ServiceLocator.html )

This can be a bottleneck only if you are working in a distributed enviroment (ie, your JNDI provider is on another JVM/server) because building the InitialContext and retrieving the DS can be costly, but don't worry about it until you need to.

Hope this help,

Rafael

PS: BTW, I guess that when you said "releases a Connection from the pool" you mean "it gets a Connection from the pool" :)