/*
 * 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;

import java.io.InputStream;
import java.io.IOException;
import java.net.URL;
import java.net.MalformedURLException;
import java.util.Enumeration;


/**
 * 
 * Defines a set of methods that a servlet uses to communicate with its
 * servlet container, for example, to get the MIME type of a file, dispatch
 * requests, or write to a log file.
 *
 * <p>There is one context per "web application" per Java Virtual Machine.  (A
 * "web application" is a collection of servlets and content installed under a
 * specific subset of the server's URL namespace such as <code>/catalog</code>
 * and possibly installed via a <code>.war</code> file.) 
 *
 * <p>In the case of a web
 * application marked "distributed" in its deployment descriptor, there will
 * be one context instance for each virtual machine.  In this situation, the 
 * context cannot be used as a location to share global information (because
 * the information won't be truly global).  Use an external resource like 
 * a database instead.
 *
 * <p>The <code>ServletContext</code> object is contained within 
 * the {@link ServletConfig} object, which the Web server provides the
 * servlet when the servlet is initialized.
 *
 * @author 	Various
 * @version 	$Version$
 *
 * @see 	Servlet#getServletConfig
 * @see 	ServletConfig#getServletContext
 *
 */

public interface ServletContext {


    /**
     * Returns a <code>ServletContext</code> object that 
     * corresponds to a specified URL on the server.
     *
     * <p>This method allows servlets to gain
     * access to the context for various parts of the server, and as
     * needed obtain {@link RequestDispatcher} objects from the context.
     * The given path must be absolute (beginning with "/") and is 
     * interpreted based on the server's document root. 
     * 
     * <p>In a security conscious environment, the servlet container may
     * return <code>null</code> for a given URL.
     *       
     * @param uripath 	a <code>String</code> specifying the absolute URL of 
     *			a resource on the server
     *
     * @return		the <code>ServletContext</code> object that
     *			corresponds to the named URL
     *
     * @see 		RequestDispatcher
     *
     */

    public ServletContext getContext(String uripath);
    
    

    /**
     * Returns the major version of the Java Servlet API that this
     * servlet container supports. All implementations that comply
     * with Version 2.2 must have this method
     * return the integer 2.
     *
     * @return 		2
     *
     */
    
    public int getMajorVersion();
    
    

    /**
     * Returns the minor version of the Servlet API that this
     * servlet container supports. All implementations that comply
     * with Version 2.2 must have this method
     * return the integer 2.
     *
     * @return 		2
     *
     */

    public int getMinorVersion();
    
    

    /**
     * Returns the MIME type of the specified file, or <code>null</code> if 
     * the MIME type is not known. The MIME type is determined
     * by the configuration of the servlet container, and may be specified
     * in a web application deployment descriptor. Common MIME
     * types are <code>"text/html"</code> and <code>"image/gif"</code>.
     *
     *
     * @param   file    a <code>String</code> specifying the name
     *			of a file
     *
     * @return 		a <code>String</code> specifying the file's MIME type
     *
     */

    public String getMimeType(String file);
    
    

    /**
     * Returns a URL to the resource that is mapped to a specified
     * path. The path must begin with a "/" and is interpreted
     * as relative to the current context root.
     *
     * <p>This method allows the servlet container to make a resource 
     * available to servlets from any source. Resources 
     * can be located on a local or remote
     * file system, in a database, or in a <code>.war</code> file. 
     *
     * <p>The servlet container must implement the URL handlers
     * and <code>URLConnection</code> objects that are necessary
     * to access the resource.
     *
     * <p>This method returns <code>null</code>
     * if no resource is mapped to the pathname.
     *
     * <p>Some containers may allow writing to the URL returned by
     * this method using the methods of the URL class.
     *
     * <p>The resource content is returned directly, so be aware that 
     * requesting a <code>.jsp</code> page returns the JSP source code.
     * Use a <code>RequestDispatcher</code> instead to include results of 
     * an execution.
     *
     * <p>This method has a different purpose than
     * <code>java.lang.Class.getResource</code>,
     * which looks up resources based on a class loader. This
     * method does not use class loaders.
     * 
     * @param path 				a <code>String</code> specifying
     *						the path to the resource
     *
     * @return 					the resource located at the named path,
     * 						or <code>null</code> if there is no resource
     *						at that path
     *
     * @exception MalformedURLException 	if the pathname is not given in 
     * 						the correct form
     *
     */
    
    public URL getResource(String path) throws MalformedURLException;
    
    

    /**
     * Returns the resource located at the named path as
     * an <code>InputStream</code> object.
     *
     * <p>The data in the <code>InputStream</code> can be 
     * of any type or length. The path must be specified according
     * to the rules given in <code>getResource</code>.
     * This method returns <code>null</code> if no resource exists at
     * the specified path. 
     * 
     * <p>Meta-information such as content length and content type
     * that is available via <code>getResource</code>
     * method is lost when using this method.
     *
     * <p>The servlet container must implement the URL handlers
     * and <code>URLConnection</code> objects necessary to access
     * the resource.
     *
     * <p>This method is different from 
     * <code>java.lang.Class.getResourceAsStream</code>,
     * which uses a class loader. This method allows servlet containers 
     * to make a resource available
     * to a servlet from any location, without using a class loader.
     * 
     *
     * @param name 	a <code>String</code> specifying the path
     *			to the resource
     *
     * @return 		the <code>InputStream</code> returned to the 
     *			servlet, or <code>null</code> if no resource
     *			exists at the specified path 
     *
     *
     */

    public InputStream getResourceAsStream(String path);
    



    /**
     * 
     * Returns a {@link RequestDispatcher} object that acts
     * as a wrapper for the resource located at the given path.
     * A <code>RequestDispatcher</code> object can be used to forward 
     * a request to the resource or to include the resource in a response.
     * The resource can be dynamic or static.
     *
     * <p>The pathname must begin with a "/" and is interpreted as relative
     * to the current context root.  Use <code>getContext</code> to obtain
     * a <code>RequestDispatcher</code> for resources in foreign contexts.
     * This method returns <code>null</code> if the <code>ServletContext</code>
     * cannot return a <code>RequestDispatcher</code>.
     *
     * @param path 	a <code>String</code> specifying the pathname
     *			to the resource
     *
     * @return 		a <code>RequestDispatcher</code> object
     *			that acts as a wrapper for the resource
     *			at the specified path
     *
     * @see 		RequestDispatcher
     * @see 		ServletContext#getContext
     *
     */

    public RequestDispatcher getRequestDispatcher(String path);



    /**
     * Returns a {@link RequestDispatcher} object that acts
     * as a wrapper for the named servlet.
     *
     * <p>Servlets (and JSP pages also) may be given names via server 
     * administration or via a web application deployment descriptor.
     * A servlet instance can determine its name using 
     * {@link ServletConfig#getServletName}.
     *
     * <p>This method returns <code>null</code> if the 
     * <code>ServletContext</code>
     * cannot return a <code>RequestDispatcher</code> for any reason.
     *
     * @param name 	a <code>String</code> specifying the name
     *			of a servlet to wrap
     *
     * @return 		a <code>RequestDispatcher</code> object
     *			that acts as a wrapper for the named servlet
     *
     * @see 		RequestDispatcher
     * @see 		ServletContext#getContext
     * @see 		ServletConfig#getServletName
     *
     */

    public RequestDispatcher getNamedDispatcher(String name);