/*
 * @(#)Control.java	1.5 00/02/02
 *
 * Copyright 1999, 2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package javax.naming.ldap;

/**
  * This interface represents an LDAPv3 control as defined in 
  * <A HREF="ftp://ftp.isi.edu/in-notes/rfc2251.txt">RFC 2251</A>.
  *<p>
  * The LDAPv3 protocol uses controls to send and receive additional data
  * to affect the behavior of predefined operations. 
  * Controls can be sent along with any LDAP operation to the server.
  * These are referred to as <em>request controls</em>. For example, a
  * "sort" control can be sent with an LDAP search operation to
  * request that the results be returned in a particular order.
  * Solicited and unsolicited controls can also be returned with
  * responses from the server. Such controls are referred to as
  * <em>response controls</em>. For example, an LDAP server might 
  * define a special control to return change notifications.
  *<p>
  * This interface is used to represent both request and response controls.
  * 
  * @author Rosanna Lee
  * @author Scott Seligman
  * @author Vincent Ryan
  * @version 1.5 00/02/02
  *
  * @see ControlFactory
  * @since 1.3
  */
public interface Control extends java.io.Serializable {
    /**
      * Indicates a critical control.
      * The value of this constant is <tt>true</tt>.
      */
    public static final boolean CRITICAL = true;

    /**
      * Indicates a non-critical control.
      * The value of this constant is <tt>false</tt>.
      */
    public static final boolean NONCRITICAL = false;

    /**
      * Retrieves the object identifier assigned for the LDAP control.
      *
      * @return The non-null object identifier string.
      */
    public String getID();

    /**
      * Determines the criticality of the LDAP control.
      * A critical control must not be ignored by the server.
      * In other words, if the server receives a critical control
      * that it does not support, regardless of whether the control
      * makes sense for the operation, the operation will not be performed
      * and an <tt>OperationNotSupportedException</tt> will be thrown.
      * @return true if this control is critical; false otherwise.
      */
    public boolean isCritical();

    /**
      * Retrieves the ASN.1 BER encoded value of the LDAP control.
      * The result is the raw BER bytes including the tag and length of
      * the control's value. It does not include the controls OID or criticality.
      *
      * Null is returned if the value is absent.
      *
      * @return A possibly null byte array representing the ASN.1 BER encoded
      *         value of the LDAP control.
      */
    public byte[] getEncodedValue();

    // static final long serialVersionUID = -591027748900004825L;
}