Provides support for LDAPv3 extended operations and controls.

  Provides support for LDAPv3 extended operations and controls.

This package extends the directory operations of the Java Naming and Directory Interface^TM (JNDI).   JNDI provides naming and directory functionality to applications written in the Java programming language. It is designed to be independent of any specific naming or directory service implementation. Thus a variety of services--new, emerging, and already deployed ones--can be accessed in a common way.

This package is for applications and service providers that deal with LDAPv3 extended operations and controls, as defined by RFC 2251. The core interface in this package is LdapContext, which defines methods on a context for performing extended operations and handling controls.

Extended Operations

This package defines the interface ExtendedRequest to represent the argument to an extended operation, and the interface ExtendedResponse to represent the result of the extended operation. An extended response is always paired with an extended request but not necessarily vice versa. That is, you can have an extended request that has no corresponding extended response.

An application typically does not deal directly with these interfaces. Instead, it deals with classes that implement these interfaces. The application gets these classes either as part of a repertoire of extended operations standardized through the IETF, or from directory vendors for vendor-specific extended operations. The request classes should have constructors that accept arguments in a type-safe and user-friendly manner, while the response classes should have access methods for getting the data of the response in a type-safe and user-friendly manner. Internally, the request/response classes deal with encoding and decoding BER values.

For example, suppose an LDAP server supports a "get time" extended operation. It would supply classes such as GetTimeRequest and GetTimeResponse, so that applications can use this feature. An application would use these classes as follows:

GetTimeResponse resp =
    (GetTimeResponse) ectx.extendedOperation(new GetTimeRequest());
long time = resp.getTime();

The GetTimeRequest and GetTimeResponse classes might be defined as follows:

public class GetTimeRequest implements ExtendedRequest {
    // User-friendly constructor 
    public GetTimeRequest() {
    };

    // Methods used by service providers
    public String getID() {
        return GETTIME_REQ_OID;
    }
    public byte[] getEncodedValue() {
        return null;  // no value needed for get time request
    }
    public ExtendedResponse createExtendedResponse(
        String id, byte[] berValue, int offset, int length) throws NamingException {
        return new GetTimeResponse(id, berValue, offset, length);
    }
}
public class GetTimeResponse() implements ExtendedResponse {
    long time;
    // called by GetTimeRequest.createExtendedResponse()
    public GetTimeResponse(String id, byte[] berValue, int offset, int length) 
        throws NamingException {
        // check validity of id
        long time =  ... // decode berValue to get time
    }

    // Type-safe and User-friendly methods
    public java.util.Date getDate() { return new java.util.Date(time); }
    public long getTime() { return time; }

    // Low level methods
    public byte[] getEncodedValue() {
        return // berValue saved;
    }
    public String getID() {
        return GETTIME_RESP_OID;
    }
}

Controls

This package defines the interface Control to represent an LDAPv3 control. It can be a control that is sent to an LDAP server (request control) or a control returned by an LDAP server (response control). Unlike extended requests and responses, there is not necessarily any pairing between request controls and response controls. You can send request controls and expect no response controls back, or receive response controls without sending any request controls.

An application typically does not deal directly with this interface. Instead, it deals with classes that implement this interface. The application gets control classes either as part of a repertoire of controls standardized through the IETF, or from directory vendors for vendor-specific controls. The request control classes should have constructors that accept arguments in a type-safe and user-friendly manner, while the response control classes should have access methods for getting the data of the response in a type-safe and user-friendly manner. Internally, the request/response control classes deal with encoding and decoding BER values.

For example, suppose an LDAP server supports a "signed results" request control, which when sent with a request, asks the server to digitally sign the results of an operation. It would supply a class SignedResultsControl so that applications can use this feature. An application would use this class as follows:

Control[] reqCtls = new Control[] {new SignedResultsControl(Control.CRITICAL)};
ectx.setRequestControls(reqCtls);
NamingEnumeration enum = ectx.search(...);

The SignedResultsControl class might be defined as follows:

public class SignedResultsControl implements Control {
    // User-friendly constructor 
    public SignedResultsControl(boolean criticality) {
        // assemble the components of the request control
    };

    // Methods used by service providers
    public String getID() {
        return // control's object identifier
    }
    public byte[] getEncodedValue() {
        return // ASN.1 BER encoded control value
    }
    ...
}

When a service provider receives response controls, it uses the ControlFactory class to produce specific classes that implement the Control interface.

An LDAP server can send back response controls with an LDAP operation and also with enumeration results, such as those returned by a list or search operation. The LdapContext provides a method (getResponseControls()) for getting the response controls sent with an LDAP operation, while the HasControls interface is used to retrieve response controls associated with enumeration results.

For example, suppose an LDAP server sends back a "change ID" control in response to a successful modification. It would supply a class ChangeIDControl so that the application can use this feature. An application would perform an update, and then try to get the change ID.

// Perform update
Context ctx = ectx.createSubsubcontext("cn=newobj");

// Get response controls
Control[] respCtls = ectx.getResponseControls();
if (respCtls != null) {
    // Find the one we want
    for (int i = 0; i < respCtls; i++) {
        if(respCtls[i] instanceof ChangeIDControl) {
            ChangeIDControl cctl = (ChangeIDControl)respCtls[i];
            System.out.println(cctl.getChangeID());
        }
    }
}

The vendor might supply the following ChangeIDControl and VendorXControlFactory classes. The VendorXControlFactory will be used by the service provider when the provider receives response controls from the LDAP server.

public class ChangeIDControl implements Control {
    long id;

    // Constructor used by ControlFactory
    public ChangeIDControl(String OID, byte[] berVal) throws NamingException {
        // check validity of OID
        id = // extract change ID from berVal
    };

    // Type-safe and User-friendly method
    public long getChangeID() {
        return id;
    }

    // Low-level methods
    public String getID() {
        return CHANGEID_OID;
    }
    public byte[] getEncodedValue() {
        return // original berVal
    }
    ...
}
public class VendorXControlFactory extends ControlFactory {
    public VendorXControlFactory () {
    }

    public Control getControlInstance(Control orig) throws NamingException {
        if (isOneOfMyControls(orig.getID())) {
            ... 

            // determine which of ours it is and call its constructor
            return (new ChangeIDControl(orig.getID(), orig.getEncodedValue()));
        }
        return null;  // not one of ours
    }
}

Package Specification

The JNDI API Specification and related documents can be found in the JNDI documentation.