Parallel Processing A - Plain JavaSpaces - TransactionHelper.java

/**
 * 
 * Title: 		TransactionHelper
 * Description: Helps to get handle to a Transaction. Created using standard Jini lookup.
 * 				This class supplays an interface to get a transaction manager service 
 * 				(Started before running the application using "startJiniTXNMngr.bat/sh")
 * 				and a transaction proxy connected to it.
 * 
 */
package com.gigaspaces.examples.tutorials.plainjavaspaces;

import net.jini.core.transaction.Transaction;
import net.jini.core.transaction.TransactionFactory;

import net.jini.core.transaction.server.TransactionManager;
import java.rmi.RMISecurityManager;
import net.jini.core.discovery.LookupLocator;
import net.jini.core.entry.Entry;

import net.jini.core.lookup.ServiceRegistrar;
import net.jini.core.lookup.ServiceTemplate;
import net.jini.lookup.entry.Name;
import java.net.*;

import java.io.*;
import java.rmi.*;
 
  public class TransactionHelper {
      private static TransactionHelper me = null;
      private TransactionManager trManager=null;
      public TransactionHelper() {
      }
  
      public static TransactionHelper getInstance(){
          if(me==null){
              me = new TransactionHelper();
          }
          return me;
      }
     
      /**
       * 	getJiniTransaction
       *	Returns a transaction manager proxy.
       *	
       *	@param timeout 	- The length of time our transaction should live before timing out.
       *    @return Transaction.Created
       *    @throws Exception      		  
       */
     
      public Transaction.Created getJiniTransaction(long timeout) throws Exception {
    	  if (null == trManager) {
    		  trManager = findTransactionManager();
    	  }
          Transaction.Created tCreated = TransactionFactory.create(trManager,timeout);
          return tCreated;
      }
  
      private TransactionManager findTransactionManager(){
         if ( System.getSecurityManager() == null ){
        	 System.setSecurityManager(new RMISecurityManager());
         }
         
         // Creating service template to find transaction manager service by matching fields.
         Class [] classes = new Class[]{net.jini.core.transaction.server.TransactionManager.class};
         Name sn = new Name( "*" );
         ServiceTemplate tmpl = new ServiceTemplate(null,classes,
           new Entry[] {  } );
         
         // Creating a lookup locator.
         LookupLocator locator = null;
         try {
             locator = new LookupLocator("jini://localhost");
         } catch (MalformedURLException ex) {
             System.out.println(ex.getMessage());
             ex.printStackTrace();
         }
         
         ServiceRegistrar sr = null;
         try {
             sr = locator.getRegistrar();
         } catch (ClassNotFoundException ex1) {
             ex1.printStackTrace();
         } catch (IOException ex1) {
             ex1.printStackTrace();
         }
         
         TransactionManager tm = null;
         try {
             tm = (TransactionManager) sr.lookup(tmpl);
         } catch (RemoteException ex2) {
             ex2.printStackTrace();
         }
         return tm;
     }
 }