/*
    * $Id: AbstractServlet.java 269 2005-08-10 17:49:22Z josem $
    *
    * Tarsis
    * Copyright (C) 2002 Talika Open Source Group
    *
    * This program 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.
   *
   * This program 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.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *
   */
  
  package org.talika.tarsis.servlets;
  
  import java.io.IOException;
  
  import javax.servlet.ServletConfig;
  import javax.servlet.ServletException;
  import javax.servlet.UnavailableException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.talika.tarsis.Globals;
  import org.talika.tarsis.context.Context;
  import org.talika.tarsis.log.Logger;
  
  /**
   * Base implementation of <code>HttpServlet</code> for all web application servlets
   * of Tarsis MV Framework architecture.
   *
   * @author  Jose M. Palomar
   * @version $Revision: 269 $
   */
  public abstract class AbstractServlet extends HttpServlet {
  
      // Fields
      /**
       * Tarsis context.
       */
      private Context context;
  
      /**
       * Tarsis logger.
       */
      private Logger logger;
  
      /**
       * Servlet name.
       */
      private String servletName;
  
      /**
       * Called by the servlet container to indicate to a servlet that the servlet is
       * being placed into service.
       *
       * @param config ServletConfig the <code>ServletConfig</code> object that contains
       * configutation information for this servlet.
       * @throws ServletException if an exception occurs that interrupts the servlet's
       * normal operation.
       * @see javax.servlet.Servlet#init(javax.servlet.ServletConfig)
       */
      public void init(ServletConfig config) throws ServletException {
          super.init(config);
  
          // Obtain context
          this.context = (Context) config.getServletContext().getAttribute(Globals.CONTEXT_ATTR);
          if (this.context == null) {
              throw new UnavailableException("Null context!");
          }
  
          this.logger = this.context.getLogger();
          this.servletName = config.getServletName();
  
          if (this.logger.isInfoEnabled()) {
              this.logger.logInfo(servletName + ": init");
          }
  
      }
  
      /**
       * Called by the servlet container to indicate to a servlet that the servlet is
       * being taken out of service.
       *
       * @see javax.servlet.Servlet#destroy()
       */
      public void destroy() {
  
          if (this.logger.isInfoEnabled()) {
             this.logger.logInfo(servletName + ": destroy");
         }
 
     }
 
     /**
      * Called by the server to allow a servlet to handle a GET request.
      *
      * @param request servlet object that contains the request the client has made of
      * the servlet.
      * @param response servlet object that contains the response the servlet sends to
      * the client.
      * @throws ServletException if the request could not be handled.
      * @throws IOException if an input or output error is detected when the servlet
      * handles request.
      */
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
     throws ServletException, IOException {
         if (this.logger.isDebugEnabled()) {
             this.logger.logDebug(servletName + ": invoked (GET)");
         }
         process(request, response);
     }
 
     /**
      * Called by the server to allow a servlet to handle a POST request.
      *
      * @param request servlet object that contains the request the client has made of
      * the servlet.
      * @param response servlet object that contains the response the servlet sends to
      * the client.
      * @throws ServletException if the request could not be handled.
      * @throws IOException if an input or output error is detected when the servlet
      * handles request.
      */
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
     throws ServletException, IOException {
         if (this.logger.isDebugEnabled()) {
             this.logger.logDebug(servletName + ": invoked (POST)");
         }
         process(request, response);
     }
 
     /**
      * Processes requests for both HTTP GET and POST methods.
      *
      * @param request servlet object that contains the request the client has made of
      * the servlet.
      * @param response servlet object that contains the response the servlet sends to
      * the client.
      * @throws ServletException if the request could not be handled.
      * @throws IOException if an input or output error is detected when the servlet
      * handles request.
      */
     protected abstract void process(HttpServletRequest request, HttpServletResponse response)
     throws ServletException, IOException;
 
     /**
      * Returns the Tarsis context.
      *
      * @return Context the Tarsis context.
      */
     protected final Context getContext() {
         return context;
     }
 
     /**
      * Returns the Tarsis logger.
      *
      * @return Logger the Tarsis logger.
      */
     protected final Logger getLogger() {
         return logger;
     }
 
     /**
      * Returns a short description of the servlet.
      *
      * @return String a short description of the servlet.
      * @see javax.servlet.Servlet#getServletInfo()
      */
     public final String getServletInfo() {
         return Globals.PROJECT_INFO + "/" + servletName;
     }
 
 }