package zenitek.workflow;

import java.util.Map;
import java.util.Hashtable;
import javax.ejb.EJBHome;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;
/**
 * @author db2admin
 *
 * This class is to cache EJB home Interfaces for the purpose of improve 
 * JNDI lookup performance.
 * 
 */
public class EJBHomeFactory {
  private static EJBHomeFactory instance;
  private Map homeInterfaces;
  private Context ctx;
  private String type;

  //This is private, and cannot instantiated directly.
  private EJBHomeFactory() throws NamingException {
    //Initiated cantainer for EJB home interfaces.
    homeInterfaces = new Hashtable();

    //Get the context for caching purposes.
    ctx = new InitialContext();
  }

  public static EJBHomeFactory getInstance() throws NamingException {
    if (instance == null) {
      instance = new EJBHomeFactory();
    }
    return instance;
  }

  public EJBHome lookup(String jndiName, Class homeInterfaceClass)
    throws NamingException {
    //See if we already have this interface cached.
    EJBHome homeInterface = (EJBHome) homeInterfaces.get(homeInterfaceClass);

    //If not, look up with the supplied JNDI name.
    if (homeInterface == null) {
      Object obj = ctx.lookup(jndiName);
      homeInterface =
        (EJBHome) PortableRemoteObject.narrow(obj, homeInterfaceClass);

      //If this is a new ref,save for caching purposes.
      homeInterfaces.put(homeInterfaceClass, homeInterface);

      System.out.println("We get a non-cached home interface.");
    } else {
      System.out.println("We get a cached home interface.");
    }
    System.out.println("Now cache size : " + homeInterfaces.size());
    return homeInterface;
  }
}