/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
*
* Free SoftwareFoundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package javax.servlet;
import java.io.IOException;
/**
* A servlet is any Java class with a null-arg constructor that
* implements the Servlet API.
*
* <p>Simple servlets should extend HttpServlet to create servlets.
*
* <p>Servlets that need full control should extend GenericServlet.
*
* <h4>Location</h4>
*
* Servlets are usually loaded from WEB-INF/classes under the application's
* root. To add a servlet test.MyServlet, create the java file:
* <center>/www/myweb/WEB-APP/classes/test/MyServlet.java</center>
*
* <p>Servlets can also live in the global classpath.
*
* <h4>Configuration</h4>
*
* Servlet configuration for Resin is in the resin.conf file.
*
* <pre><code>
* <servlet servlet-name='hello'
* servlet-class='test.HelloServlet'
* load-on-startup>
* <init-param param1='value1'/>
* <init-param param2='value2'/>
* </servlet>
* </code></pre>
*
* <h4>Dispatch</h4>
*
* The servlet engine selects servlets based on the
* <code>servlet-mapping</code> configuration. Servlets can use the
* special 'invoker' servlet or they can be configured to execute directly.
*
* <p>To get a path info, your servlet needs to use a wildcard. In the
* following example, /Hello will match the 'hello' servlet, but
* /Hello/there will match the 'defaultServlet' servlet with a pathinfo
* of /Hello/there.
*
* <pre><code>
* <servlet-mapping url-pattern='/'
* servlet-name='defaultServlet'/>
*
* <servlet-mapping url-pattern='/Hello'
* servlet-name='hello'/>
*
* <servlet-mapping url-pattern='/servlet/*'
* servlet-name='invoker'/>
*
* <servlet-mapping url-pattern='*.jsp'
* servlet-name='com.caucho.jsp.JspServlet'/>
* </code></pre>
*
* <h4>Life cycle</h4>
*
* Servlets are normally initialized when they are first loaded. You can
* force loading on startup using the 'load-on-startup' attribute to the
* servlet configuration. This is a useful technique for the equivalent
* of the global.jsa file.
*
* <p>A servlet can count on having only one instance per
* application (JVM) unless it implements SingleThreadedModel.
*
* <p>Servlet requests are handed by the <code>service</code> routine.
* Since the servlet engine is multithreaded, multiple threads may call
* <code>service</code> simultaneously.
*
* <p>When the application closes, the servlet engine will call
* <code>destroy</code>. Note, applications always close and are restarted
* whenever a servlet changes. So <code>init</code> and <code>destroy</code>
* may be called many times while the server is still up.
*/
public interface Servlet {
/**
* Returns an information string about the servlet.
*/
public String getServletInfo();
/**
* Initialize the servlet. ServletConfig contains servlet parameters
* from the configuration file. GenericServlet will store the config
* for later use.
*
* @param config information from the configuration file.
*/
public void init(ServletConfig config) throws ServletException;
/**
* Returns the servlet configuration, usually the same value as passed
* to the init routine.
*/
public ServletConfig getServletConfig();
/**
* Service a request. Since the servlet engine is multithreaded,
* many threads may execute <code>service</code> simultaneously. Normally,
* <code>req</code> and <code>res</code> will actually be
* <code>HttpServletRequest</code> and <code>HttpServletResponse</code>
* classes.
*
* @param req request information. Normally servlets will cast this
* to <code>HttpServletRequest</code>
* @param res response information. Normally servlets will cast this
* to <code>HttpServletRequest</code>
*/
public void service(ServletRequest req, ServletResponse res)
throws IOException, ServletException;
/**
* Called when the servlet shuts down. Servlets can use this to close
* database connections, etc. Servlets generally only shutdown when
* the application closes.
*/
public void destroy();
}