/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * ====================================================================
 *
 * This source code implements specifications defined by the Java
 * Community Process. In order to remain compliant with the specification
 * DO NOT add / change / or delete method signatures!
 */ 

package javax.servlet.http;

import javax.servlet.ServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;

/**
 *
 * Extends the {@link ServletResponse} interface to provide HTTP-specific
 * functionality in sending a response.  For example, it has methods
 * to access HTTP headers and cookies.
 *
 * <p>The servlet container creates an <code>HttpServletRequest</code> object
 * and passes it as an argument to the servlet's service methods
 * (<code>doGet</code>, <code>doPost</code>, etc).
 *
 * 
 * @author	Various
 * @version	$Version$
 *
 * @see		javax.servlet.ServletResponse
 *
 */



public interface HttpServletResponse extends ServletResponse {

    /**
     * Adds the specified cookie to the response.  This method can be called
     * multiple times to set more than one cookie.
     *
     * @param cookie the Cookie to return to the client
     *
     */

    public void addCookie(Cookie cookie);

    /**
     * Returns a boolean indicating whether the named response header 
     * has already been set.
     * 
     * @param	name	the header name
     * @return		<code>true</code> if the named response header 
     *			has already been set; 
     * 			<code>false</code> otherwise
     */

    public boolean containsHeader(String name);

    /**
     * Encodes the specified URL by including the session ID in it,
     * or, if encoding is not needed, returns the URL unchanged.
     * The implementation of this method includes the logic to
     * determine whether the session ID needs to be encoded in the URL.
     * For example, if the browser supports cookies, or session
     * tracking is turned off, URL encoding is unnecessary.
     * 
     * <p>For robust session tracking, all URLs emitted by a servlet 
     * should be run through this
     * method.  Otherwise, URL rewriting cannot be used with browsers
     * which do not support cookies.
     *
     * @param	url	the url to be encoded.
     * @return		the encoded URL if encoding is needed;
     * 			the unchanged URL otherwise.
     */

    public String encodeURL(String url);

    /**
     * Encodes the specified URL for use in the
     * <code>sendRedirect</code> method or, if encoding is not needed,
     * returns the URL unchanged.  The implementation of this method
     * includes the logic to determine whether the session ID
     * needs to be encoded in the URL.  Because the rules for making
     * this determination can differ from those used to decide whether to
     * encode a normal link, this method is seperate from the
     * <code>encodeURL</code> method.
     * 
     * <p>All URLs sent to the <code>HttpServletResponse.sendRedirect</code>
     * method should be run through this method.  Otherwise, URL
     * rewriting cannot be used with browsers which do not support
     * cookies.
     *
     * @param	url	the url to be encoded.
     * @return		the encoded URL if encoding is needed;
     * 			the unchanged URL otherwise.
     *
     * @see #sendRedirect
     * @see #encodeUrl
     */

    public String encodeRedirectURL(String url);

    /**
     * @deprecated	As of version 2.1, use encodeURL(String url) instead
     *
     * @param	url	the url to be encoded.
     * @return		the encoded URL if encoding is needed; 
     * 			the unchanged URL otherwise.
     */

    public String encodeUrl(String url);
    
    /**
     * @deprecated	As of version 2.1, use 
     *			encodeRedirectURL(String url) instead
     *
     * @param	url	the url to be encoded.
     * @return		the encoded URL if encoding is needed; 
     * 			the unchanged URL otherwise.
     */

    public String encodeRedirectUrl(String url);

    /**
     * Sends an error response to the client using the specified status
     * code and descriptive message.  The server generally creates the 
     * response to look like a normal server error page.
     *
     * <p>If the response has already been committed, this method throws 
     * an IllegalStateException.
     * After using this method, the response should be considered
     * to be committed and should not be written to.
     *
     * @param	sc	the error status code
     * @param	msg	the descriptive message
     * @exception	IOException	If an input or output exception occurs
     * @exception	IllegalStateException	If the response was committed
     *						before this method call
     */

    public void sendError(int sc, String msg) throws IOException;

    /**
     * Sends an error response to the client using the specified
     * status.  The server generally creates the 
     * response to look like a normal server error page.
     *
     * <p>If the response has already been committed, this method throws 
     * an IllegalStateException.
     * After using this method, the response should be considered
     * to be committed and should not be written to.
     *
     * @param	sc	the error status code
     * @exception	IOException	If an input or output exception occurs
     * @exception	IllegalStateException	If the response was committed
     */

    public void sendError(int sc) throws IOException;

    /**
     * Sends a temporary redirect response to the client using the
     * specified redirect location URL.  This method can accept relative URLs;
     * the servlet container will convert the relative URL to an absolute URL
     * before sending the response to the client.
     *
     * <p>If the response has already been committed, this method throws 
     * an IllegalStateException.
     * After using this method, the response should be considered
     * to be committed and should not be written to.
     *
     * @param		location	the redirect location URL
     * @exception	IOException	If an input or output exception occurs
     * @exception	IllegalStateException	If the response was committed
     */

    public void sendRedirect(String location) throws IOException;
    
    /**
     * 
     * Sets a response header with the given name and
     * date-value.  The date is specified in terms of
     * milliseconds since the epoch.  If the header had already
     * been set, the new value overwrites the previous one.  The
     * <code>containsHeader</code> method can be used to test for the
     * presence of a header before setting its value.
     * 
     * @param	name	the name of the header to set
     * @param	value	the assigned date value
     * 
     * @see #containsHeader
     * @see #addDateHeader
     */

    public void setDateHeader(String name, long date);
    
    /**
     * 
     * Adds a response header with the given name and
     * date-value.  The date is specified in terms of
     * milliseconds since the epoch.  This method allows response headers 
     * to have multiple values.
     * 
     * @param	name	the name of the header to set
     * @param	value	the additional date value
     * 
     * @see #setDateHeader
     */

    public void addDateHeader(String name, long date);
    
    /**
     *
     * Sets a response header with the given name and value.
     * If the header had already been set, the new value overwrites the
     * previous one.  The <code>containsHeader</code> method can be
     * used to test for the presence of a header before setting its
     * value.
     * 
     * @param	name	the name of the header
     * @param	value	the header value
     *
     * @see #containsHeader
     * @see #addHeader
     */

    public void setHeader(String name, String value);
    
    /**
     * Adds a response header with the given name and value.
     * This method allows response headers to have multiple values.
     * 
     * @param	name	the name of the header
     * @param	value	the additional header value
     *
     * @see #setHeader
     */

    public void addHeader(String name, String value);

    /**
     * Sets a response header with the given name and
     * integer value.  If the header had already been set, the new value
     * overwrites the previous one.  The <code>containsHeader</code>
     * method can be used to test for the presence of a header before
     * setting its value.
     *
     * @param	name	the name of the header
     * @param	value	the assigned integer value
     *
     * @see #containsHeader
     * @see #addIntHeader
     */

    public void setIntHeader(String name, int value);

    /**
     * Adds a response header with the given name and
     * integer value.  This method allows response headers to have multiple
     * values.
     *
     * @param	name	the name of the header
     * @param	value	the assigned integer value
     *
     * @see #setIntHeader
     */

    public void addIntHeader(String name, int value);


    
    /**
     * Sets the status code for this response.  This method is used to
     * set the return status code when there is no error (for example,
     * for the status codes SC_OK or SC_MOVED_TEMPORARILY).  If there