Chapter 4 Writing an LDAP Client

This chapter describes the general process of writing an LDAP client. The chapter covers the procedures for connecting to an LDAP server, authenticating, requesting operations, and disconnecting from the server.

• "Overview: Designing an LDAP Client"
• "Creating a Connection and Setting Preferences"
• "Connecting to the LDAP Server"
• "Binding and Authenticating to an LDAP Server"
• "Performing LDAP Operations"
• "Closing the Connection to the Server"

1. Create a new LDAPConnection object, and set any preferences that you want applied to all LDAP operations. (See "Creating a Connection and Setting Preferences" for details.)
2. Connect to an LDAP server. (See "Connecting to the LDAP Server" for details.)
3. If necessary, bind to the LDAP server. If you intend to use any of the LDAP v3 features (such as controls or extended operations), specify the version of LDAP supported by your client. (See "Binding and Authenticating to an LDAP Server" for details.)
4. Perform the operations (for example, search the directory or modify entries in the directory). (See "Performing LDAP Operations" for details.)
5. When you are done, disconnect from the LDAP server. (See "Closing the Connection to the Server" for details.)

import netscape.ldap.*;

import java.util.*;

public class SimpleExample {

   public static void main( String[] args )

   {

      /* Step 1: Create a new connection. */

      LDAPConnection ld = new LDAPConnection();



      try {

         /* Step 2: Connect to an LDAP server. */

         ld.connect( "localhost", LDAPv2.DEFAULT_PORT );



         /* Step 3: Authenticate to the server. 

            If you do not specify a version number, 

            this method authenticates your client 

            as an LDAP v2 client (not LDAP v3). */

         ld.authenticate( "uid=bjensen,ou=People,o=Airius.com",

            "hifalutin" );



         /* Step 4: Perform your LDAP operations. */

         /* Search for all entries with the last name "Jensen". */

         LDAPSearchResults results = ld.search( "o=Airius.com",

            LDAPv2.SCOPE_SUB, "(sn=Jensen)", null, false );

         /* Print the DNs of the matching entries. */

         while ( results.hasMoreElements() ) {

            LDAPEntry entry = null;

            try {

               entry = results.next();

               System.out.println( entry.getDN() );

            } catch ( LDAPReferralException e ) {

               System.out.println( "Search references: " );

               LDAPUrl refUrls[] = e.getURLs();

               for ( int i=0; i < refUrls.length; i++ ) {

                  System.out.println( "\t" + refUrls[i].getURL() );

               }

               continue;

            } catch ( LDAPException e ) {

               System.out.println( "Error: " + e.toString() );

               continue;

            }

         }

      } catch( LDAPException e ) {

         System.out.println( "Error: " + e.toString() );

      }



      /* Step 5: Disconnect from the server when done. */

      try {

         ld.disconnect();

      } catch( LDAPException e ) {

         System.out.println( "Error: " + e.toString() );

         System.exit(1);

      }

      System.exit(0);

   }

}

LDAPConnection ld = new LDAPConnection();

In addition, the object also contains preferences for the LDAP session (for example, whether or not referrals are automatically followed).

LDAPConnection ld = new LDAPConnection();

ld.connect( "ldap.airius.com", LDAPv2.DEFAULT_PORT ); 

LDAPConnection ld = new LDAPConnection();

ld.connect( "ldap1.airius.com ldap2.airus.com:3890 

   ldap3.airius.com:39000", LDAPv2.DEFAULT_PORT );

• the LDAP version of the client
• the DN that the client is attempting to authenticate as
• the method of authentication that should be used
• the credentials to be used for authentication

• You want to authenticate to the server.

For example, you may want to add or modify entries in the directory, which requires you to authenticate as a user with access privileges.

• You are connecting to an LDAP v2 server.

LDAP v2 servers typically require clients to bind before any operations can be performed. (Note that the Netscape Directory Server 1.0x is an LDAP v2 server but does not require clients to bind.)

• "Understanding Authentication Methods"
• "Using Simple Authentication"
• "Binding Anonymously"
• "Specifying the LDAP Version"
• "Authenticating with the connect Method"

LDAPConnection ld = new LDAPConnection();

ld.connect( "ldap.airius.com", LDAPv2.DEFAULT_PORT ); 

ld.authenticate( "uid=bjensen,ou=People,o=Airius.com", "hifalutin" );

LDAPConnection ld = new LDAPConnection();

ld.connect( "ldap.airius.com", LDAPv2.DEFAULT_PORT ); 

ld.authenticate( null, null );

• Specify version 3 when invoking the authenticate method. For example:

   LDAPConnection ld = new LDAPConnection();

   ld.connect( "ldap.airius.com", LDAPv2.DEFAULT_PORT ); 

   ld.authenticate( 3, null, null );

• Invoke the setOption method of the LDAPConnection object to set the LDAPv2.PROTOCOL_VERSION preference to 3, then invoke the authenticate method. For example:

   LDAPConnection ld = new LDAPConnection();

   ld.connect( "ldap.airius.com", LDAPv2.DEFAULT_PORT ); 

   ld.setOption( LDAPv2.PROTOCOL_VERSION, 3 );

   ld.authenticate( null, null );

LDAPConnection ld = new LDAPConnection();

ld.connect( 3, "ldap.airius.com", DEFAULT_PORT, 

   "uid=bjensen,ou=People,o=Airius.com", "hifalutin" );

• To search for entries in the directory, use the search method (see "Searching the Directory" for details).
• To retrieve a single entry in the directory, use the read method (see "Searching the Directory" for details).
• To determine whether an attribute contains a certain value, use the compare method (see "Comparing the Value of an Attribute" for details).
• To add entries to the directory, use the add method (see "Adding a New Entry" for details).
• To modify entries in the directory, use the modify method (see "Modifying an Entry" for details).
• To delete entries from the directory, use the delete method (see "Deleting an Entry" for details).
• To rename entries in the directory, use the rename method (see "Changing the Name of an Entry" for details).

LDAPConnection ld = new LDAPConnection();

ld.connect( "ldap.airius.com", LDAPv2.DEFAULT_PORT ); 

...

/* Authenticate and perform LDAP operations on the server. */

...

ld.disconnect();