/**
 *  A code example of Persistent Search Control JNDI Client 
 *  Note: This example has been tested to work with SunOne Directory Server
 *        It doesn't work with Active Directory.
 */
import javax.naming.*;
import javax.naming.directory.*;
import javax.naming.event.*;
import javax.naming.ldap.*;

import java.util.Hashtable;
import java.io.*;

public class PersistentSearchControlJndiClient 
{
	   
  static final String PERSISTENT_SEARCH_OID = "2.16.840.1.113730.3.4.3";
  static final String QUIT_PROMPT = "\nEnter 'q' to quit: ";
	
  public static void main(String[] args)
  {
    LdapContext   rootContext;
    EventDirContext eventContext;

    //create initial context
    Hashtable env = new Hashtable();
    env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
    env.put(Context.PROVIDER_URL, "ldap://myserevr.mycompany.com:389");
    env.put(Context.SECURITY_AUTHENTICATION, "simple");
    env.put(Context.SECURITY_PRINCIPAL, "cn=directory manager");
    env.put(Context.SECURITY_CREDENTIALS, "mypassword");
    env.put(Context.BATCHSIZE, "1");  //return each change as it occurs
    env.put("java.naming.ldap.derefAliases", "never");
    
    try{
      // creating the initial context performs the LDAP bind
      rootContext = new InitialLdapContext(env, null);

      // verify that persistent search is supported, exit if not supported
      if (!isPersistentSearchSupported(rootContext)){
        System.out.println(
        		"The LDAP Server does not support persistent search");
        System.exit(1);
      }

      // do a look up of the search base to create an EventDirContext
      // to which the search listener can be added.
      eventContext = (EventDirContext)rootContext.lookup("dc=mydomain,dc=com");

      // create a MyEventListener instance to listen for events
      MyEventListener listener = new MyEventListener("mylistener");

      // Set up the search constraints
      SearchControls constraints = new SearchControls();
      constraints.setSearchScope(SearchControls.SUBTREE_SCOPE);

      // Add the naming listener to the searchBase context. The interface
      // methods of the listener will be called in a separate thread when
      // a relevant event occurs
      eventContext.addNamingListener(
        "",         //use the eventContext object as the target
        "(objectClass=*)",  //filter, include all objects
        constraints,    //search the subtree below the eventContext
        listener);      //the listener object

      // loop until the user enters a q to quit.
      BufferedReader in
        = new BufferedReader(new InputStreamReader(System.in));
      try{
        String input;
        while (true){
          System.out.print(QUIT_PROMPT);
          input = in.readLine();
          if ( input.startsWith("q") || input.startsWith("Q") )
            break;
        }
      }
      catch(IOException e)
      {
        System.out.println(e.getMessage());
      }

      // Not strictly necessary since the context is closed below
      eventContext.removeNamingListener(listener);

      // Close context when we're done
      eventContext.close();

    }
    catch(AuthenticationException e)
    {
      System.out.println(e.getMessage());
    }
    catch(NamingException e)
    {
      System.out.println(e.getMessage());
    }
  }

  /**
   * isPersistentSearchSupported
   *
   * Query the rootDSE to find out if the persistent search control
   * is supported.
   */
  static boolean isPersistentSearchSupported(
                  LdapContext rootContext) throws NamingException
  {
    SearchResult     rootDSE;
    NamingEnumeration  searchResults;
    Attributes       attrs;
    NamingEnumeration  attrEnum;
    Attribute      attr;
    NamingEnumeration  values;
    String         value;
    String[]       attrNames = {"supportedControl"};
    SearchControls     searchControls = new SearchControls();

    searchControls.setCountLimit(0);  //0 means no limit
    searchControls.setReturningAttributes(attrNames);
    searchControls.setSearchScope(SearchControls.OBJECT_SCOPE);

    // search for the rootDSE object
    searchResults =
       rootContext.search("", "(objectClass=*)", searchControls);

    while (searchResults.hasMore())
    {
      rootDSE = (SearchResult)searchResults.next();

      attrs = rootDSE.getAttributes();
      attrEnum = attrs.getAll();
      while (attrEnum.hasMore())
      {
        attr = (Attribute)attrEnum.next();
        values = attr.getAll();
        while (values.hasMore())
        {
          value = (String) values.next();
          if (value.equals(PERSISTENT_SEARCH_OID))
            return true;
        }
      }
    }
    return false;
  }


  /**
   * MyEventlistener class
   * An instance of this class is registered with an EventDirContext object.
   * The registered instance's NamespaceChangeListener interface methods are
   * called when a pertinent event occurs.
   */
  static class MyEventListener implements NamespaceChangeListener,
                      ObjectChangeListener
  {
    private String id;

    public MyEventListener(String id)
    {
      this.id = id;
    }

    public void objectAdded(NamingEvent evt)
    {
      System.out.println(
       "\n\n" + id + ">>> object added event. Object Name: " +
       evt.getNewBinding().getName());
      System.out.print(QUIT_PROMPT);
    }

    public void objectRemoved(NamingEvent evt)
    {
      System.out.println(
       "\n\n" + id + ">>> object removed event. Object Name: " +
       evt.getOldBinding().getName());
      System.out.print(QUIT_PROMPT);
    }

    public void objectRenamed(NamingEvent evt)
    {
      System.out.println(
       "\n\n" + id + ">>> object renamed event. New name: " +
       evt.getNewBinding().getName() +
       " Old name: " + evt.getOldBinding().getName());
      System.out.print(QUIT_PROMPT);
    }

    public void objectChanged(NamingEvent evt)
    {
      System.out.println(
       "\n\n" + id + ">>> object changed event. Object name: " +
       evt.getNewBinding().getName());
      System.out.print(QUIT_PROMPT);
    }

    public void namingExceptionThrown(NamingExceptionEvent evt)
    {
      System.out.println(
        "\n\n" + id + ">>> Listener received a naming exception");
      evt.getException().printStackTrace();
      System.out.print(QUIT_PROMPT);
    }
  }
} 

public void objectChanged(NamingEvent evt)
{
    System.out.println(
            "\n\n" + id + ">>> object changed event. Object name: " +
            evt.getNewBinding().getName());
    
    // In order to get the detailed information as to what had really changed, 
    // another search based on the returned name is required.  
    try{
    	EventDirContext eDir = (EventDirContext)evt.getEventContext();
    	// The following command will trigger additional search 
    	// request (without PersistentSearchControl)
    	Attributes attrs = eDir.getAttributes(evt.getNewBinding().getName(), null);
    	Enumeration enu = attrs.getAll();
    	while(enu.hasMoreElements()){
    		Attribute attr = (Attribute)enu.nextElement();
            System.out.println(attr.getID() + ": " + attr.get());
    	}
    }catch(Exception e){
    	e.printStackTrace();
    }
    
    System.out.print(QUIT_PROMPT);
}