/**
 * 
 * VLVJndiClient.java
 * Sample code to demostrate how Virtual List View (VLV) Control works.
 * Note:
 * 	  1) Note: JNDI Boost package is required for this example to run.
 * 	  2) VLV Control MUST be used in conjunction with Sort Control.
 *       Otherwise, you will be braced by:  [LDAP: error code 60 - VLV Control]
 *    3) SunOne Directory Server supports VLV & Microsoft supports VLV since AD2003 
 * 
 */

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

import javax.naming.*;
import javax.naming.directory.*;
import javax.naming.ldap.*;

import com.sun.jndi.ldap.ctl.VirtualListViewControl;
import com.sun.jndi.ldap.ctl.VirtualListViewResponseControl;
import com.sun.jndi.ldap.ctl.SortControl;

public class VLVJndiClient 
{
	   
  static final String  VLV_CONTROL_OID = "2.16.840.1.113730.3.4.9";
	
  public static void main(String[] args) throws IOException 
  {
      Hashtable env = new Hashtable();
        
      env.put(Context.INITIAL_CONTEXT_FACTORY, 
                  "com.sun.jndi.ldap.LdapCtxFactory");
            
      env.put(Context.PROVIDER_URL, "ldap://myserver.mydomain.com:389");
      env.put(Context.SECURITY_AUTHENTICATION, "simple");
      env.put(Context.SECURITY_PRINCIPAL, "mybinddn");
      env.put(Context.SECURITY_CREDENTIALS, "mypassword");
        
      try {
          /* Create initial context with no connection request controls */
          LdapContext ctx = new InitialLdapContext(env, null);
    	    
          /* Query the server to see if the VLV Control is supported */ 
          if (!isVLVControlSupported(ctx)){
               System.out.println(
	         "The server does not support Virtual List View (VLV) Control.");
               System.exit(1);
          }

          /* Sort Control is required for VLV to work */
          SortControl sctl = new SortControl(
	   		new String[]{"cn"}, // sort by cn 
	    		Control.CRITICAL
		    );

          /* VLV that returns the first 20 answers */
          VirtualListViewControl vctl = 
               new VirtualListViewControl(1, 0, 0, 19, Control.CRITICAL); 

          /* Set context's request controls */ 
          ctx.setRequestControls(new Control[]{sctl, vctl});
    

          /* Perform search */
          NamingEnumeration answer = 
              ctx.search("ou=people,dc=com", "(objectclass=*)", null);
	
          /* Enumerate search results */
          while (answer.hasMore()) {
              SearchResult si = (SearchResult)answer.next();
              System.out.println(si.getName());
          }

          /* examine the response controls (if any) */
          printControls(ctx.getResponseControls());
	
          ctx.close();
	    
      } catch (NamingException e) {
		    e.printStackTrace();
      }
  }

  static void printControls(Control[] controls) 
  {
      if(controls == null){
          System.out.println("No response controls");
          return;
      }
    	
      for(int j = 0; j < controls.length; j++) {
          if(controls[j] instanceof SortResponseControl){
              SortResponseControl src = (SortResponseControl)controls[j];
              if (src.isSorted()) {
                  System.out.println("Sorted-Search completed successfully");
              } else {
                  System.out.println(
                      "Sorted-Search did not complete successfully: error (" +
                      src.getResultCode() + ") on attribute '" + 
                      src.getAttributeID() + "'");
              }
          }else if(controls[j] instanceof VirtualListViewResponseControl){
              VirtualListViewResponseControl vlv =
                      (VirtualListViewResponseControl)controls[j];
              if (vlv.getResultCode() == 0) {
                  System.out.println("Sorted-View completed successfully");
                  System.out.println("TargetOffset: " + vlv.getTargetOffset());
                  System.out.println("ListSize: " + vlv.getListSize());
              } else {
                  System.out.println("Sorted-View did not complete successfully: " 
	               			+ vlv.getResultCode());
              }
          } else {
              System.out.println("Received control: "+ controls[j].getID());
          }
      }
  }
    
  /**
   * Is VLV Control supported?
   *
   * Query the rootDSE object to find out if VLV Control
   * is supported.
   */
  static boolean isVLVControlSupported(LdapContext ctx) 
	throws NamingException
  {
      SearchControls ctl = new SearchControls();
      ctl.setReturningAttributes(new String[]{"supportedControl"});
      ctl.setSearchScope(SearchControls.OBJECT_SCOPE);

      /* search for the rootDSE object */
      NamingEnumeration results = ctx.search("", "(objectClass=*)", ctl);

      while(results.hasMore()){
          SearchResult entry = (SearchResult)results.next();
          NamingEnumeration attrs = entry.getAttributes().getAll();
          while (attrs.hasMore()){
              Attribute attr = (Attribute)attrs.next();
              NamingEnumeration vals = attr.getAll();
              while (vals.hasMore()){
                  String value = (String) vals.next();
                  if (value.equals(VLV_CONTROL_OID))
                        return true;
              }
          }
      }
      return false;
  }
    
}