/*
 * @(#)LdapContext.java	1.8 01/12/03
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.naming.ldap;

import javax.naming.NamingException;
import javax.naming.directory.DirContext;
import java.util.Hashtable;

/**
 * This interface represents a context in which you can perform
 * operations with LDAPv3-style controls and perform LDAPv3-style
 * extended operations.
 * 
 * For applications that do not require such controls or extended
 * operations, the more generic <tt>javax.naming.directory.DirContext</tt>
 * should be used instead.
 * 
 * <h3>Usage Details About Controls</h3>
 * 
 * This interface provides support for LDAP v3 controls.  
 * At a high level, this support allows a user
 * program to set request controls for LDAP operations that are executed
 * in the course of the user program's invocation of 
 * <tt>Context</tt>/<tt>DirContext</tt>
 * methods, and read response controls resulting from LDAP operations.
 * At the implementation level, there are some details that developers of
 * both the user program and service providers need to understand in order 
 * to correctly use request and response controls.
 * 
 * <h3>Request Controls</h3>
 * <p>
 * There are two types of request controls:
 * <ul>
 * <li>Request controls that affect how a connection is created
 * <li>Request controls that affect context methods
 * </ul>
 * 
 * The former is used whenever a connection needs to be established or
 * re-established with an LDAP server. The latter is used when all other
 * LDAP operations are sent to the LDAP server.  The reason why a
 * distinction between these two types of request controls is necessary
 * is because JNDI is a high-level API that does not deal directly with
 * connections.  It is the job of service providers to do any necessary
 * connection management. Consequently, a single
 * connection may be shared by multiple context instances, and a service provider
 * is free to use its own algorithms to conserve connection and network
 * usage. Thus, when a method is invoked on the context instance, the service
 * provider might need to do some connection management in addition to
 * performing the corresponding LDAP operations. For connection management,
 * it uses the <em>connection request controls</em>, while for the normal
 * LDAP operations, it uses the <em>context request controls</em>.
 *<p>Unless explicitly qualified, the term "request controls" refers to
 * context request controls.
 * 
 * <h4>Context Request Controls</h4>
 * There are two ways in which a context instance gets its request controls:
 * <ol>
 * <tt>
 * <li>ldapContext.newInstance(<strong>reqCtls</strong>)
 * <li>ldapContext.setRequestControls(<strong>reqCtls</strong>)
 * </tt>
 * </ol>
 * where <tt>ldapContext</tt> is an instance of <tt>LdapContext</tt>.
 * Specifying <tt>null</tt> or an empty array for <tt>reqCtls</tt>
 * means no request controls.
 * <tt>newInstance()</tt> creates a new instance of a context using
 * <tt>reqCtls</tt>, while <tt>setRequestControls()</tt>
 * updates an existing context instance's request controls to <tt>reqCtls</tt>.
 * <p>
 * Unlike environment properties, request controls of a context instance
 * <em>are not inherited</em> by context instances that are derived from
 * it.  Derived context instances have <tt>null</tt> as their context
 * request controls.  You must set the request controls of a derived context
 * instance explicitly using <tt>setRequestControls()</tt>.
 * <p>
 * A context instance's request controls are retrieved using
 * the method <tt>getRequestControls()</tt>.
 * 
 * <h4>Connection Request Controls</h4>
 * There are three ways in which connection request controls are set:
 * <ol>
 * <tt>
 * <li>
 * new InitialLdapContext(env, <strong>connCtls</strong>)
 * <li>refException.getReferralContext(env, <strong>connCtls</strong>)
 * <li>ldapContext.reconnect(<strong>connCtls</strong>);
 * </tt>
 * </ol>
 * where <tt>refException</tt> is an instance of
 * <tt>LdapReferralException</tt>, and <tt>ldapContext</tt> is an
 * instance of <tt>LdapContext</tt>.
 * Specifying <tt>null</tt> or an empty array for <tt>connCtls</tt>
 * means no connection request controls.
 * <p>
 * Like environment properties, connection request controls of a context
 * <em>are inherited</em> by contexts that are derived from it.
 * Typically, you initialize the connection request controls using the
 * <tt>InitialLdapContext</tt> constructor or
 * <tt>LdapReferralContext.getReferralContext()</tt>. These connection
 * request controls are inherited by contexts that share the same
 * connection--that is, contexts derived from the initial or referral
 * contexts.  
 * <p>
 * Use <tt>reconnect()</tt> to change the connection request controls of
 * a context.  
 * Invoking <tt>ldapContext.reconnect()</tt> affects only the
 * connection used by <tt>ldapContext</tt> and any new contexts instances that are
 * derived form <tt>ldapContext</tt>. Contexts that previously shared the
 * connection with <tt>ldapContext</tt> remain unchanged. That is, a context's
 * connection request controls must be explicitly changed and is not
 * affected by changes to another context's connection request
 * controls.
 * <p>
 * A context instance's connection request controls are retrieved using
 * the method <tt>getConnectControls()</tt>.
 * 
 * <h4>Service Provider Requirements</h4>
 * 
 * A service provider supports connection and context request controls
 * in the following ways.  Context request controls must be associated on
 * a per context instance basis while connection request controls must be
 * associated on a per connection instance basis.  The service provider
 * must look for the connection request controls in the environment
 * property "java.naming.ldap.control.connect" and pass this environment
 * property on to context instances that it creates.
 * 
 * <h3>Response Controls</h3>
 * 
 * The method <tt>LdapContext.getResponseControls()</tt> is used to
 * retrieve the response controls generated by LDAP operations executed
 * as the result of invoking a <tt>Context</tt>/<tt>DirContext</tt>
 * operation. The result is all of the responses controls generated
 * by the underlying LDAP operations, including any implicit reconnection.
 * To get only the reconnection response controls, 
 * use <tt>reconnect()</tt> followed by <tt>getResponseControls()</tt>.
 * 
 * <h3>Parameters</h3>
 *
 * A <tt>Control[]</tt> array
 * passed as a parameter to any method is owned by the caller.
 * The service provider will not modify the array or keep a reference to it,
 * although it may keep references to the individual <tt>Control</tt> objects
 * in the array.
 * A <tt>Control[]</tt> array returned by any method is immutable, and may
 * not subsequently be modified by either the caller or the service provider.
 * 
 * @author Rosanna Lee
 * @author Scott Seligman
 * @author Vincent Ryan
 * @version 1.8 01/12/03
 *
 * @see InitialLdapContext
 * @see LdapReferralException#getReferralContext(java.util.Hashtable,javax.naming.ldap.Control[])
 * @since 1.3
 */

public interface LdapContext extends DirContext {
   /**
    * Performs an extended operation.
    *
    * This method is used to support LDAPv3 extended operations.
    * @param request The non-null request to be performed.
    * @return The possibly null response of the operation. null means
    * the operation did not generate any response.
    * @throws NamingException If an error occurred while performing the
    * extended operation.
    */
    public ExtendedResponse extendedOperation(ExtendedRequest request)
	throws NamingException;

    /**
     * Creates a new instance of this context initialized using request controls.
     *
     * This method is a convenience method for creating a new instance
     * of this context for the purposes of multithreaded access.
     * For example, if multiple threads want to use different context
     * request controls,
     * each thread may use this method to get its own copy of this context
     * and set/get context request controls without having to synchronize with other 
     * threads.
     *<p>
     * The new context has the same environment properties and connection 
     * request controls as this context. See the class description for details.
     * Implementations might also allow this context and the new context
     * to share the same network connection or other resources if doing 
     * so does not impede the independence of either context.
     *
     * @param requestControls The possibly null request controls 
     * to use for the new context.
     * If null, the context is initialized with no request controls.
     *
     * @return A non-null <tt>LdapContext</tt> instance.
     * @exception NamingException If an error occurred while creating
     * the new instance.
     * @see InitialLdapContext
     */
    public LdapContext newInstance(Control[] requestControls)
	throws NamingException;

    /**
     * Reconnects to the LDAP server using the supplied controls and 
     * this context's environment.
     *<p>
     * This method is a way to explicitly initiate an LDAP "bind" operation.
     * For example, you can use this method to set request controls for
     * the LDAP "bind" operation, or to explicitly connect to the server 
     * to get response controls returned by the LDAP "bind" operation.
     *<p>
     * This method sets this context's <tt>connCtls</tt>
     * to be its new connection request controls. This context's
     * context request controls are not affected.
     * After this method has been invoked, any subsequent 
     * implicit reconnections will be done using <tt>connCtls</tt>.
     * <tt>connCtls</tt> are also used as
     * connection request controls for new context instances derived from this
     * context.
     * These connection request controls are not
     * affected by <tt>setRequestControls()</tt>.
     *<p>
     * Service provider implementors should read the "Service Provider" section
     * in the class description for implementation details.
     * @param connCtls The possibly null controls to use. If null, no
     * controls are used.
     * @exception NamingException If an error occurred while reconnecting.
     * @see #getConnectControls
     * @see #newInstance
     */
    public void reconnect(Control[] connCtls) throws NamingException;

    /**
     * Retrieves the connection request controls in effect for this context.
     * The controls are owned by the JNDI implementation and are
     * immutable. Neither the array nor the controls may be modified by the
     * caller.
     *
     * @return A possibly-null array of controls. null means no connect controls
     * have been set for this context.
     * @exception NamingException If an error occurred while getting the request
     * controls.
     */
    public Control[] getConnectControls() throws NamingException;

    /**
     * Sets the request controls for methods subsequently 
     * invoked on this context.
     * The request controls are owned by the JNDI implementation and are
     * immutable. Neither the array nor the controls may be modified by the
     * caller.
     * <p>
     * This removes any previous request controls and adds
     * <tt>requestControls</tt> 
     * for use by subsequent methods invoked on this context.
     * This method does not affect this context's connection request controls.
     *<p>
     * Note that <tt>requestControls</tt> will be in effect until the next
     * invocation of <tt>setRequestControls()</tt>. You need to explicitly
     * invoke <tt>setRequestControls()</tt> with <tt>null</tt> or an empty
     * array to clear the controls if you don't want them to affect the
     * context methods any more.
     * To check what request controls are in effect for this context, use
     * <tt>getRequestControls()</tt>.
     * @param requestControls The possibly null controls to use. If null, no
     * controls are used.
     * @exception NamingException If an error occurred while setting the
     * request controls.
     * @see #getRequestControls
     */
    public void setRequestControls(Control[] requestControls)
	throws NamingException;

    /**
     * Retrieves the request controls in effect for this context.
     * The request controls are owned by the JNDI implementation and are
     * immutable. Neither the array nor the controls may be modified by the
     * caller.
     *
     * @return A possibly-null array of controls. null means no request controls
     * have been set for this context.
     * @exception NamingException If an error occurred while getting the request
     * controls.
     * @see #setRequestControls
     */
    public Control[] getRequestControls() throws NamingException;

    /**
     * Retrieves the response controls produced as a result of the last
     * method invoked on this context.
     * The response controls are owned by the JNDI implementation and are
     * immutable. Neither the array nor the controls may be modified by the
     * caller.
     *<p>
     * These response controls might have been generated by a successful or
     * failed operation.
     *<p>
     * When a context method that may return response controls is invoked,
     * response controls from the previous method invocation are cleared.
     * <tt>getResponseControls()</tt> returns all of the response controls
     * generated by LDAP operations used by the context method in the order
     * received from the LDAP server.
     * Invoking <tt>getResponseControls()</tt> does not
     * clear the response controls. You can call it many times (and get
     * back the same controls) until the next context method that may return
     * controls is invoked.
     *<p>
     * @return A possibly null array of controls. If null, the previous
     * method invoked on this context did not produce any controls.
     * @exception NamingException If an error occurred while getting the response
     * controls.
     */
    public Control[] getResponseControls() throws NamingException;

    /**
     * Constant that holds the name of the environment property
     * for specifying the list of control factories to use. The value
     * of the property should be a colon-separated list of the fully
     * qualified class names of factory classes that will create a control
     * given another control. See
     * <tt>ControlFactory.getControlInstance()</tt> for details.
     * This property may be specified in the environment, an applet
     * parameter, a system property, or one or more resource files.
     *<p>
     * The value of this constant is "java.naming.factory.control".
     *<p>
     * @see ControlFactory
     * @see javax.naming.Context#addToEnvironment
     * @see javax.naming.Context#removeFromEnvironment
     */
    static final String CONTROL_FACTORIES = "java.naming.factory.control";
}
