javax.servlet/src/main/java/javax/servlet/http/HttpSession.java

/*
 * Copyright 1999,2005 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package javax.servlet.http;


/**
 *
 * Provides a way to identify a user across more than one page
 * request or visit to a Web site and to store information about that user.
 *
 * <p>The servlet container uses this interface to create a session
 * between an HTTP client and an HTTP server. The session persists
 * for a specified time period, across more than one connection or
 * page request from the user. A session usually corresponds to one
 * user, who may visit a site many times. The server can maintain a
 * session in many ways such as using cookies or rewriting URLs.
 *
 * <p>This interface allows servlets to
 * <ul>
 * <li>View and manipulate information about a session, such as
 *     the session identifier, creation time, and last accessed time
 * <li>Bind objects to sessions, allowing user information to persist
 *     across multiple user connections
 * </ul>
 *
 * <p>When an application stores an object in or removes an object from a
 * session, the session checks whether the object implements
 * {@link HttpSessionBindingListener}. If it does,
 * the servlet notifies the object that it has been bound to or unbound
 * from the session. Notifications are sent after the binding methods complete.
 * For session that are invalidated or expire, notifications are sent after
 * the session has been invalidatd or expired.
 *
 * <p>A servlet should be able to handle cases in which
 * the client does not choose to join a session, such as when cookies are
 * intentionally turned off. Until the client joins the session,
 * <code>isNew</code> returns <code>true</code>.  If the client chooses
 * not to join
 * the session, <code>getSession</code> will return a different session
 * on each request, and <code>isNew</code> will always return
 * <code>true</code>.
 *
 * <p>Session information is scoped only to the current web application
 * (<code>ServletContext</code>), so information stored in one context
 * will not be directly visible in another.
 *
 * @author	Various
 * @version	$Version$
 *
 *
 * @see 	HttpSessionBindingListener
 * @see 	HttpSessionContext
 *
 */

public interface HttpSession {




    /**
     *
     * Returns the time when this session was created, measured
     * in milliseconds since midnight January 1, 1970 GMT.
     *
     * @return				a <code>long</code> specifying
     * 					when this session was created,
     *					expressed in
     *					milliseconds since 1/1/1970 GMT
     *
     * @exception IllegalStateException	if this method is called on an
     *					invalidated session
     *
     */

    public long getCreationTime();




    /**
     *
     * Returns a string containing the unique identifier assigned
     * to this session. The identifier is assigned
     * by the servlet container and is implementation dependent.
     *
     * @return				a string specifying the identifier
     *					assigned to this session
     *
     * @exeption IllegalStateException	if this method is called on an
     *					invalidated session
     *
     */

    public String getId();




    /**
     *
     * Returns the last time the client sent a request associated with
     * this session, as the number of milliseconds since midnight
     * January 1, 1970 GMT, and marked by the time the container recieved the request.
     *
     * <p>Actions that your application takes, such as getting or setting
     * a value associated with the session, do not affect the access
     * time.
     *
     * @return				a <code>long</code>
     *					representing the last time
     *					the client sent a request associated
     *					with this session, expressed in
     *					milliseconds since 1/1/1970 GMT
     *
     * @exeption IllegalStateException	if this method is called on an
     *					invalidated session
     *
     */

    public long getLastAccessedTime();


    /**
     *
     * Specifies the time, in seconds, between client requests before the
     * servlet container will invalidate this session.  A negative time
     * indicates the session should never timeout.
     *
     * @param interval		An integer specifying the number
     * 				of seconds
     *
     */

    public void setMaxInactiveInterval(int interval);




   /**
    * Returns the maximum time interval, in seconds, that
    * the servlet container will keep this session open between
    * client accesses. After this interval, the servlet container
    * will invalidate the session.  The maximum time interval can be set
    * with the <code>setMaxInactiveInterval</code> method.
    * A negative time indicates the session should never timeout.
    *
    *
    * @return		an integer specifying the number of
    *			seconds this session remains open
    *			between client requests
    *
    * @see		#setMaxInactiveInterval
    *
    *
    */

    public int getMaxInactiveInterval();




   /**
    *
    * @deprecated 	As of Version 2.1, this method is
    *			deprecated and has no replacement.
    *			It will be removed in a future
    *			version of the Java Servlet API.
    *
    */

    public HttpSessionContext getSessionContext();




    /**
     *
     *
     * @param name		a string specifying the name of the object
     *
     * @return			the object with the specified name
     *
     * @exception IllegalStateException	if this method is called on an
     *					invalidated session
     *
     */

    public Object getValue(String name);




    /**
     *
     *
     * @return				an array of <code>String</code>
     *					objects specifying the
     *					names of all the objects bound to
     *					this session
     *
     * @exception IllegalStateException	if this method is called on an
     *					invalidated session
     *
     */

    public String[] getValueNames();




    /**
     *
     *
     * @param name			the name to which the object is bound;
     *					cannot be null
     *
     * @param value			the object to be bound; cannot be null
     *
     * @exception IllegalStateException	if this method is called on an
     *					invalidated session
     *
     */

    public void putValue(String name, Object value);





    /**
     *
     *
     * @param name				the name of the object to
     *						remove from this session
     *
     * @exception IllegalStateException	if this method is called on an
     *					invalidated session
     */

    public void removeValue(String name);




    /**
     *
     * Invalidates this session then unbinds any objects bound
     * to it.
     *
     * @exception IllegalStateException	if this method is called on an
     *					already invalidated session
     *
     */

    public void invalidate();




    /**
     *
     * Returns <code>true</code> if the client does not yet know about the
     * session or if the client chooses not to join the session.  For
     * example, if the server used only cookie-based sessions, and
     * the client had disabled the use of cookies, then a session would
     * be new on each request.
     *
     * @return 				<code>true</code> if the
     *					server has created a session,
     *					but the client has not yet joined
     *
     * @exception IllegalStateException	if this method is called on an
     *					already invalidated session
     *
     */

    public boolean isNew();
}