WebUIServlet


1   /*
2    * Copyright (c) 2003 - 2007 OpenSubsystems s.r.o. Slovak Republic. All rights reserved.
3    * 
4    * Project: OpenSubsystems
5    * 
6    * $Id: WebUIServlet.java,v 1.16 2007/02/20 04:12:15 bastafidli Exp $
7    * 
8    * This program is free software; you can redistribute it and/or modify
9    * it under the terms of the GNU General Public License as published by
10   * the Free Software Foundation; version 2 of the License. 
11   * 
12   * This program is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   * GNU General Public License for more details.
16   * 
17   * You should have received a copy of the GNU General Public License
18   * along with this program; if not, write to the Free Software
19   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
20   */
21  
22  package org.opensubsystems.core.www;
23  
24  import java.io.IOException  ;
25  import java.util.HashMap  ;
26  import java.util.Map  ;
27  import java.util.logging.Logger  ;
28  
29  import javax.servlet.RequestDispatcher  ;
30  import javax.servlet.ServletConfig  ;
31  import javax.servlet.ServletException  ;
32  import javax.servlet.http.HttpServletRequest  ;
33  import javax.servlet.http.HttpServletResponse  ;
34  import javax.servlet.http.HttpSession  ;
35  
36  import org.opensubsystems.core.util.CallContext;
37  import org.opensubsystems.core.util.GlobalConstants;
38  import org.opensubsystems.core.util.Log;
39  import org.opensubsystems.core.util.MyTimer;
40  
41  /**
42   * Base class for all servlets developed as part of this  project, which perform 
43   * web form processing or execute an action based on request from the user 
44   * interface. It's main responsibility is to provide default implementation if 
45   * functionality for form processing is required. 
46   *
47   * @version $Id: WebUIServlet.java,v 1.16 2007/02/20 04:12:15 bastafidli Exp $
48   * @author Miro Halas
49   * @code.reviewer Miro Halas
50   * @code.reviewed 1.9 2006/02/24 00:19:55 jlegeny
51   */
52  public class WebUIServlet extends WebSessionServlet
53  {
54     // Configuration settings ///////////////////////////////////////////////////
55  
56     /** 
57      * Property used to specify page to display messages to user for example 
58      * in case of error.
59      */   
60     public static final String   WEBUI_MESSAGEBOX_PAGE = "oss.webui.messagebox.page";
61  
62     /** 
63      * Property used to specify stylesheet used to display messages to user for 
64      * example in case of error.
65      */   
66     public static final String   WEBUI_MESSAGEBOX_STYLE_SHEET = "oss.webui.messagebox.css";
67     
68  //   /** 
69  //    * TODO: For Miro: What is this for?
70  //    */   
71  //   public static final String CLOSE_PREVIEW_PAGE = "oss.webui.closepreview.page";
72  
73     // Constants ////////////////////////////////////////////////////////////////
74  
75     /**
76      * Name of the generic attribute used to pass some string representation of 
77      * the current request to the message box page in case it wants to display 
78      * some troubleshooting information.
79      */
80     public static final String   ORIGINAL_REQUEST_INFO_REQUEST_PARAM = "originalrequest";
81  
82     /**
83      * Name of the generic attribute used to pass some data to the rendering page.
84      * Any aditional data can be passed in attributed named "databean2", "databean3", 
85      * etc.
86      */
87     public static final String   DATA_ATTRIBUTE_REQUEST_PARAM = "databean";
88  
89     /**
90      * Name of the attribute used to pass page title to the rendering pages.
91      */
92     public static final String   PAGE_TITLE_REQUEST_PARAM = "pagetitle";
93  
94     /**
95      * Name of the attribute used to pass flag if the user is logged in.
96      */
97     public static final String   LOGGEDIN_REQUEST_PARAM = "loggedin";
98     
99     /**
100     * Name of the attribute used to pass flag if the dialog has to be maximized.
101     */
102    public static final String   FORCE_MAXIMIZE_PARAM = "forcemaximize";
103 
104    /**
105     * Parameter used to identify form to be processed.
106     * @see #FORM_UNKNOWN_ID
107     * @see #getFormToProcess
108     */
109    public static final String   FORM_NAME_REQUEST_PARAM = "FORM_NAME";
110 
111    /**
112     * Constants for forms recognized by this servlet
113     * @see #FORM_NAME_REQUEST_PARAM
114     * @see #getFormToProcess
115     */
116    public static final int FORM_UNKNOWN_ID = -1;
117 
118    /**
119     * Constants for number of forms recognized by this servlet
120     */
121    public static final int FORM_COUNT_WEBUI = 0;
122 
123    // Cached values ////////////////////////////////////////////////////////////
124 
125    /**
126     * Logger for this class
127     */
128    private static Logger   s_logger = Log.getInstance(WebUIServlet.class);
129 
130    /**
131     * Style sheet used for message boxes if any.
132     */
133    protected String   m_strMessageStyleSheet;
134    
135    /**
136     * Cache where paths to individual UI pages will be stored once initialized 
137     * from configuration file.
138     * We can use notsychronized HashMap instead of synchronized Hashtable
139     * becaue once the map in inialized, it will be read only.
140     * This cache cannot be static since every instance of this servlet
141     * can be configured to use different UI.
142     */
143    private final Map   m_mpUIPathCache = new HashMap  ();
144    
145    /**
146     * Cache where initialized dispatchers to individual UI pages will be stored 
147     * once initialized. This is only if they can be cached.
148     * We can use notsychronized HashMap instead of synchronized Hashtable
149     * becaue once the map in inialized, it will be read only.
150     * This cache cannot be static since every instance of this servlet
151     * can be configured to use different UI.
152     */
153    private final Map   m_mpUIRendererCache = new HashMap  ();
154 
155    // Attributes ///////////////////////////////////////////////////////////////
156    
157    /**
158     * Generated serial version id for this class.
159     */
160    private static final long serialVersionUID = 322547463691937622L;
161 
162    // Servlet operations ///////////////////////////////////////////////////////
163 
164    /**
165     * {@inheritDoc}
166     */
167    public void init(
168       ServletConfig   scConfig
169    ) throws ServletException  
170    {
171       super.init(scConfig);
172 
173       // Cache this value
174       cacheUIPath(scConfig, WEBUI_MESSAGEBOX_PAGE, 
175                   "Path to message box page is not set in property " 
176                   + WEBUI_MESSAGEBOX_PAGE);
177 // TODO: For Miro: Remove this if you remove the lines above      
178 //      cacheUIPath(scConfig, CLOSE_PREVIEW_PAGE, 
179 //                  "Path to close preview page is not set in property " 
180 //                  + CLOSE_PREVIEW_PAGE);
181       
182       m_strMessageStyleSheet = WebUtils.readProperty(scConfig, 
183                                                      WEBUI_MESSAGEBOX_STYLE_SHEET, 
184                                                      null, 
185                                                      true);
186       if ((m_strMessageStyleSheet == null) || (m_strMessageStyleSheet.length() == 0))
187       {
188          s_logger.config(WEBUI_MESSAGEBOX_STYLE_SHEET + " = not defined");
189          // Make it null to make checking easy
190          m_strMessageStyleSheet = null;
191       }
192       else
193       {
194          s_logger.config(WEBUI_MESSAGEBOX_STYLE_SHEET + " = " 
195                          + m_strMessageStyleSheet);
196       }
197    }
198 
199    /**
200     * {@inheritDoc}
201     */
202    public String   getServletInfo(
203    )
204    {
205       return this.getClass().getName();
206    }
207 
208    // Helper methods for accessing user interface //////////////////////////////
209 
210    /**
211     * {@inheritDoc}
212     */
213    protected void preservice(
214       HttpSession           hsSession, 
215       HttpServletRequest    hsrqRequest, 
216       HttpServletResponse   hsrpResponse,
217       boolean             bLoginVerified
218    ) throws ServletException  , 
219             IOException  
220    {
221       super.preservice(hsSession, hsrqRequest, hsrpResponse, bLoginVerified);
222       
223       // All gui application may need to know if the user is logged in or not
224       setLoggedInFlag(hsrqRequest, hsrpResponse);
225    }
226 
227    /**
228     * Cache path to portion of user interface by first search servlet configuration
229     * information and if not found then other predefined locations.
230     *
231     * @param scConfig - servlet config to read parameters from
232     * @param strUIID - unique ID of the configuration parameter used to specify 
233     *                  user interface which is URL or path to some kind of 
234     *                  rendering page (e.g. JSP page)
235     * @param strErrorMessage - error message to display if the path doesn't exist
236     * @throws ServletException - problem finding the specified UI
237     */
238    protected final void cacheUIPath(
239       ServletConfig   scConfig,
240       String          strUIID,
241       String          strErrorMessage      
242    ) throws ServletException  
243    {
244       String   strUIPath;
245       
246       strUIPath = WebUtils.readProperty(scConfig, strUIID, null, false);     
247       if ((strUIPath != null) && (strUIPath.length() > 0))
248       {
249          // Found something, try to cache it
250          // Cache this value
251          m_mpUIPathCache.put(strUIID, strUIPath);
252          cacheDispatcher(strUIID, strUIPath);
253       }
254       else
255       {
256          throw new ServletException  (strErrorMessage);
257       }
258    }
259    
260    /**
261     * Cache dispatcher to given resource if caching is possible.
262     * 
263     * @param strUIID - unique ID of the configuration parameter used to specify this UI
264     * @param strUIPath - path to given resource
265     * @throws ServletException - problem finding the specified UI
266     */
267    protected final void cacheDispatcher(
268       String   strUIID,
269       String   strUIPath
270    ) throws ServletException  
271    {
272       if (isDispatcherCachingEnabled())
273       {
274          // Create dispatcher since they can be cached
275          RequestDispatcher   rdCachedDispatcher;
276          
277          rdCachedDispatcher = m_scServletContext.getRequestDispatcher(strUIPath);
278          if (rdCachedDispatcher == null)
279          {
280             throw new ServletException  ("Cannot initialize user interface handler"
281                                         + " specified by property "
282                                         + strUIID + " = " + strUIPath);
283          }
284          else
285          {
286             // Cache the dispatched
287             m_mpUIRendererCache.put(strUIID, rdCachedDispatcher);
288          }
289       }
290    }
291    
292    /**
293     * Get handle to resource responsible for rendering of specified part of UI
294     *
295     * @param strUIID - unique ID of the configuration parameter used to specify 
296     *                  UI to display. This is the same ID previously passed into 
297     *                  cacheUIPath method. 
298     * @param hsrqRequest - the servlet request.
299     * @param hsrpResponse - the servlet response.
300     * @throws ServletException - problems displaying UI
301     * @throws IOException - problems displaying UI
302     */
303    protected final void displayUI(
304       String                strUIID,
305       HttpServletRequest    hsrqRequest,
306       HttpServletResponse   hsrpResponse
307    ) throws ServletException  ,
308              IOException  
309    {
310       // In Jetty RequestDispatcher is reusable, e.g. in WebLogic it is not 
311       // so this code needs to reflect it   
312       RequestDispatcher   rdReturn;
313       String              strUIPath;     
314       MyTimer           timer = new MyTimer();
315      
316       if (isDispatcherCachingEnabled())
317       {
318          // Get the cahed copy, it was supposed to be initialized and cached
319          rdReturn = (RequestDispatcher  )m_mpUIRendererCache.get(strUIID);
320          
321          if (GlobalConstants.ERROR_CHECKING)
322          {
323             assert rdReturn != null
324                    : "Request dispatcher for " + strUIID + " wasn't cached properly.";
325          }
326       }
327       else
328       {
329          strUIPath = (String  )m_mpUIPathCache.get(strUIID);
330 
331          if (GlobalConstants.ERROR_CHECKING)
332          {
333             assert strUIPath != null
334                    : "Unknown UI rendered to retrieve " + strUIID;
335          }
336 
337          rdReturn = m_scServletContext.getRequestDispatcher(strUIPath);
338          if (rdReturn == null)
339          {
340             throw new ServletException  ("Cannot initialize user interface handler"
341                                         + " specified by property "
342                                         + strUIID + " = " + strUIPath);
343          }
344       }
345       
346       // When somebody is getting UI rendered, thats a good sign that processing 
347       // is done so add error messages to the request    
348       hsrqRequest.setAttribute(MessageTag.MESSAGES_REQUEST_PARAM, 
349                                CallContext.getInstance().getMessages());
350       
351       if (hsrqRequest.getParameter(FORCE_MAXIMIZE_PARAM) != null)
352       {
353          // set up force maximize flag into the request attribute
354          hsrqRequest.setAttribute(FORCE_MAXIMIZE_PARAM, "true");
355       }
356         
357       rdReturn.forward(hsrqRequest, hsrpResponse);
358       timer.stop();
359       s_logger.fine("Displaying of " + strUIID + " took " + timer.toString());
360    }
361    
362    // Helper methods for generating pages //////////////////////////////////////
363 
364    /**
365     * If the user has logged in, this method will set necessary flag to mark
366     * the page that way. User is logged in if the session exists and user name 
367     * is set as session attribute. If user is not logged in, the flag will be 
368     * set to the flag to false.
369     *
370     * @param  hsrqRequest  - the servlet request.
371     * @param  hsrpResponse - the servlet response.
372     */
373    protected void setLoggedInFlag(
374       HttpServletRequest    hsrqRequest,
375       HttpServletResponse   hsrpResponse
376    )
377    {
378       HttpSession   hsSession;
379       
380       // Don't create new session becaue if the session doesn't exists, user 
381       // is not logged in
382       hsSession = hsrqRequest.getSession(false);
383       
384       if (WebSessionUtils.isLoggedIn(hsSession))
385       {
386          hsrqRequest.setAttribute(LOGGEDIN_REQUEST_PARAM, Boolean.TRUE);
387       }
388       else
389       {
390          hsrqRequest.setAttribute(LOGGEDIN_REQUEST_PARAM, Boolean.FALSE);
391       }
392    }
393 
394    /**
395     * Display page with a message to the user.
396     *
397     * @param hsrqRequest  - the servlet request.
398     * @param hsrpResponse - the servlet response.
399     * @param strPageTitle - title of the message box
400     * @param strMessage - message to display in the message box
401     * @param strProceedURL - what URL to proceed to
402     * @param cause - what was the cause of the problem if any
403     * @throws ServletException - an error has occured while displaying message box
404     * @throws IOException - error writing response 
405     */
406    protected void messageBoxPage(
407       HttpServletRequest    hsrqRequest,
408       HttpServletResponse   hsrpResponse,
409       String                strPageTitle,
410       String                strMessage,
411       String                strProceedURL,
412       Throwable             cause
413    ) throws IOException  ,
414             ServletException  
415    {
416       messageBoxPage(hsrqRequest, 
417                      hsrpResponse,
418                      strPageTitle,
419                      strMessage,
420                      strProceedURL,
421                      cause,
422                      WEBUI_MESSAGEBOX_PAGE);
423    }
424 
425    /**
426     * Display page with a message to the user, when there was a file error.
427     *
428     * @param hsrqRequest  - the servlet request.
429     * @param hsrpResponse - the servlet response.
430     * @param strPageTitle - title of the message box
431     * @param strMessage - message to display in the file message box
432     * @param strProceedURL - what URL to proceed to
433     * @param cause - what was the cause of the problem if any
434     * @param strUIPage - 
435     * @throws ServletException - an error has occured while displaying file message box
436     * @throws IOException - error writing response 
437     */
438    protected void messageBoxPage(
439       HttpServletRequest    hsrqRequest,
440       HttpServletResponse   hsrpResponse,
441       String                strPageTitle,
442       String                strMessage,
443       String                strProceedURL,
444       Throwable             cause,
445       String                strUIPage
446    ) throws IOException  ,
447             ServletException  
448    {
449       if (m_strMessageStyleSheet != null)
450       {
451          hsrqRequest.setAttribute(WEBUI_MESSAGEBOX_STYLE_SHEET, 
452                                   m_strMessageStyleSheet);
453       }
454       
455       // Include the information about the original request in case we want
456       // to display it on the error page to allow troubleshooting
457       hsrqRequest.setAttribute(ORIGINAL_REQUEST_INFO_REQUEST_PARAM, 
458                                WebUtils.debug(hsrqRequest));
459       
460       // Maybe we should reconsider displaying the same page where user 
461       // came from but with message in popup window
462       hsrqRequest.setAttribute(DATA_ATTRIBUTE_REQUEST_PARAM, 
463                                (strMessage == null) ? "Unknown error has occured."
464                                                     : strMessage);
465       hsrqRequest.setAttribute(PAGE_TITLE_REQUEST_PARAM, 
466                                (strPageTitle == null) ? "Unknown error has occured."
467                                                       : strPageTitle);
468       if (strProceedURL != null)
469       {                                                      
470          hsrqRequest.setAttribute(DATA_ATTRIBUTE_REQUEST_PARAM + "2", 
471                                   strProceedURL);
472       }
473       else
474       {
475          hsrqRequest.setAttribute(DATA_ATTRIBUTE_REQUEST_PARAM + "2", 
476                                   WebCommonConstants.DEFAULT_DIRECTORY_WEB_PAGE);
477       }
478       if (cause != null)
479       {                                                      
480          hsrqRequest.setAttribute(DATA_ATTRIBUTE_REQUEST_PARAM + "3", 
481                                   cause);
482       }
483       displayUI(strUIPage, hsrqRequest, hsrpResponse);
484    }
485 
486    // Helper methods for processing forms //////////////////////////////////////
487 
488    /**
489     * Examine request and find out what form needs to be processed. Unique number
490     * assigned to the form will be returned
491     *
492     * @param  hsrqRequest - the servlet request, which is used to find out
493     *                       what form needs to be processed
494     * @return int - one of the FORM_XXX constants
495     */
496    protected int getFormToProcess(
497       HttpServletRequest   hsrqRequest
498    )
499    {
500       return FORM_UNKNOWN_ID;
501    }
502 }
503
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