| // Copyright 2004 The Apache Software Foundation |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package org.apache.tapestry.vlib; |
| |
| import java.io.IOException; |
| import java.rmi.RemoteException; |
| |
| import javax.ejb.CreateException; |
| import javax.ejb.FinderException; |
| import javax.servlet.ServletException; |
| import javax.servlet.http.HttpSession; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.tapestry.ApplicationRuntimeException; |
| import org.apache.tapestry.IRequestCycle; |
| import org.apache.tapestry.StaleSessionException; |
| import org.apache.tapestry.engine.BaseEngine; |
| import org.apache.tapestry.form.IPropertySelectionModel; |
| import org.apache.tapestry.request.ResponseOutputStream; |
| import org.apache.tapestry.vlib.ejb.IBookQuery; |
| import org.apache.tapestry.vlib.ejb.IBookQueryHome; |
| import org.apache.tapestry.vlib.ejb.IOperations; |
| import org.apache.tapestry.vlib.ejb.IOperationsHome; |
| import org.apache.tapestry.vlib.ejb.Person; |
| import org.apache.tapestry.vlib.ejb.Publisher; |
| import org.apache.tapestry.vlib.pages.ApplicationUnavailable; |
| |
| /** |
| * |
| * The engine for the Virtual Library. |
| * This exists to implement the external |
| * service, which allows the {@link org.apache.tapestry.vlib.pages.ViewBook} |
| * and {@link org.apache.tapestry.vlib.pages.ViewPerson} |
| * pages to be bookmarked, and to provide |
| * a way for shutting down the application when the user logs out. |
| * |
| * |
| * @version $Id$ |
| * @author Howard Lewis Ship |
| * |
| **/ |
| |
| public class VirtualLibraryEngine extends BaseEngine |
| { |
| public static final Log LOG = LogFactory.getLog(VirtualLibraryEngine.class); |
| |
| private static final boolean DEBUG_ENABLED = |
| Boolean.getBoolean("org.apache.tapestry.vlib.debug-enabled"); |
| |
| private transient boolean _killSession; |
| |
| private transient IOperations _operations; |
| private transient IPropertySelectionModel _publisherModel; |
| private transient IPropertySelectionModel _personModel; |
| |
| private transient String _applicationUnavailableMessage; |
| |
| /** |
| * Removes the operations bean instance, if accessed this request cycle. |
| * |
| * <p>May invalidate the {@link HttpSession} (see {@link #logout()}). |
| **/ |
| |
| protected void cleanupAfterRequest(IRequestCycle cycle) |
| { |
| clearCache(); |
| |
| _applicationUnavailableMessage = null; |
| |
| if (_killSession) |
| { |
| try |
| { |
| HttpSession session = cycle.getRequestContext().getSession(); |
| |
| if (session != null) |
| session.invalidate(); |
| } |
| catch (IllegalStateException ex) |
| { |
| // Ignore. |
| } |
| } |
| } |
| |
| /** |
| * Sets the visit property to null, and sets a flag that |
| * invalidates the {@link HttpSession} at the end of the request cycle. |
| * |
| **/ |
| |
| public void logout() |
| { |
| Visit visit = (Visit) getVisit(); |
| |
| if (visit != null) |
| visit.setUser(null); |
| |
| _killSession = true; |
| } |
| |
| public boolean isDebugEnabled() |
| { |
| return DEBUG_ENABLED; |
| } |
| |
| /** |
| * Returns an instance of the Vlib Operations beans, which is a stateless |
| * session bean for performing certain operations. |
| * |
| * <p>The bean is automatically removed at the end of the request cycle. |
| * |
| **/ |
| |
| public IOperations getOperations() |
| { |
| Global global = (Global) getGlobal(); |
| |
| if (_operations == null) |
| { |
| int i = 0; |
| while (true) |
| { |
| try |
| { |
| IOperationsHome home = global.getOperationsHome(); |
| |
| _operations = home.create(); |
| |
| break; |
| } |
| catch (CreateException ex) |
| { |
| throw new ApplicationRuntimeException("Error creating operations bean.", ex); |
| } |
| catch (RemoteException ex) |
| { |
| rmiFailure("Remote exception creating operations bean.", ex, i++); |
| } |
| } |
| } |
| |
| return _operations; |
| } |
| |
| /** |
| * Builds a model for entering in a publisher name, including an intial |
| * blank option. |
| * |
| **/ |
| |
| public IPropertySelectionModel getPublisherModel() |
| { |
| if (_publisherModel == null) |
| _publisherModel = buildPublisherModel(); |
| |
| return _publisherModel; |
| } |
| |
| private IPropertySelectionModel buildPublisherModel() |
| { |
| Publisher[] publishers = null; |
| |
| EntitySelectionModel model = new EntitySelectionModel(); |
| |
| // Add in a default null value, such that the user can |
| // not select a specific Publisher. |
| |
| model.add(null, ""); |
| |
| int i = 0; |
| while (true) |
| { |
| IOperations operations = getOperations(); |
| |
| try |
| { |
| publishers = operations.getPublishers(); |
| |
| // Exit the retry loop |
| |
| break; |
| } |
| catch (RemoteException ex) |
| { |
| rmiFailure("Unable to obtain list of publishers.", ex, i++); |
| } |
| } |
| |
| // Add in the actual publishers. They are sorted by name. |
| |
| for (i = 0; i < publishers.length; i++) |
| model.add(publishers[i].getId(), publishers[i].getName()); |
| |
| return model; |
| } |
| |
| /** |
| * Invoked from {@link Visit#clearCache()} (and at the end of the request |
| * cycle) to clear the publisher and person |
| * {@link IPropertySelectionModel} models. |
| * |
| **/ |
| |
| public void clearCache() |
| { |
| _publisherModel = null; |
| _personModel = null; |
| |
| Visit visit = (Visit) getVisit(); |
| |
| if (visit != null) |
| visit.clearCache(); |
| } |
| |
| /** |
| * Returns a model that contains all the known Person's, sorted by last name, |
| * then first. The label for the model matches the user's natural name. |
| * |
| **/ |
| |
| public IPropertySelectionModel getPersonModel() |
| { |
| if (_personModel == null) |
| _personModel = buildPersonModel(false); |
| |
| return _personModel; |
| } |
| |
| public IPropertySelectionModel buildPersonModel(boolean includeEmpty) |
| { |
| Person[] persons = null; |
| |
| int i = 0; |
| while (true) |
| { |
| IOperations operations = getOperations(); |
| |
| try |
| { |
| persons = operations.getPersons(); |
| |
| break; |
| } |
| catch (RemoteException ex) |
| { |
| rmiFailure("Unable to obtain list of persons.", ex, i++); |
| } |
| } |
| |
| EntitySelectionModel model = new EntitySelectionModel(); |
| |
| if (includeEmpty) |
| model.add(null, ""); |
| |
| for (i = 0; i < persons.length; i++) |
| model.add(persons[i].getId(), persons[i].getNaturalName()); |
| |
| return model; |
| |
| } |
| |
| /** |
| * Creates a new {@link IBookQuery} EJB instance. |
| * |
| **/ |
| |
| public IBookQuery createNewQuery() |
| { |
| Global global = (Global) getGlobal(); |
| |
| IBookQuery result = null; |
| |
| int i = 0; |
| while (true) |
| { |
| IBookQueryHome home = global.getBookQueryHome(); |
| |
| try |
| { |
| result = home.create(); |
| |
| break; |
| } |
| catch (CreateException ex) |
| { |
| throw new ApplicationRuntimeException("Could not create BookQuery bean.", ex); |
| } |
| catch (RemoteException ex) |
| { |
| rmiFailure("Remote exception creating BookQuery bean.", ex, i++); |
| } |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Invoked in various places to present an error message to the user. |
| * This sets the error property of either the |
| * {@link org.apache.tapestry.vlib.pages.Home} or |
| * {@link org.apache.tapestry.vlib.pages.MyLibrary} page |
| * (the latter only if the user is logged in), |
| * and sets the selected page for rendering the response. |
| * |
| **/ |
| |
| public void presentError(String error, IRequestCycle cycle) |
| { |
| String pageName = "Home"; |
| // Get, but don't create, the visit. |
| Visit visit = (Visit) getVisit(); |
| |
| if (visit != null && visit.isUserLoggedIn()) |
| pageName = "MyLibrary"; |
| |
| IErrorProperty page = (IErrorProperty) cycle.getPage(pageName); |
| |
| page.setError(error); |
| |
| cycle.activate(page); |
| } |
| |
| /** |
| * Invoked after an operation on a home or remote interface |
| * throws a RemoteException; this clears any cache of |
| * home and remote interfaces. |
| * |
| * @param message the message for the exception, or for the log message |
| * @param ex the exception thrown |
| * @param attempt the attempt number. Attempt #0 simply clears the EJBs, |
| * attempt #1 is the real failure. |
| * |
| **/ |
| |
| public void rmiFailure(String message, RemoteException ex, int attempt) |
| { |
| LOG.error(message, ex); |
| |
| clearEJBs(); |
| |
| if (attempt > 0) |
| punt(message, ex); |
| |
| } |
| |
| private void punt(String message, Throwable ex) |
| { |
| _applicationUnavailableMessage = message; |
| |
| throw new ApplicationRuntimeException(message, ex); |
| } |
| |
| private void clearEJBs() |
| { |
| Global global = (Global) getGlobal(); |
| |
| global.clear(); |
| |
| _operations = null; |
| } |
| |
| /** |
| * Invoked when any kind of runtime exception percolates up to the |
| * top level service method. Normally, the standard Exception |
| * page is displayed; we logout and setup our own version of the page |
| * instead. |
| * |
| **/ |
| |
| protected void activateExceptionPage( |
| IRequestCycle cycle, |
| ResponseOutputStream output, |
| Throwable cause) |
| throws ServletException |
| { |
| try |
| { |
| logout(); |
| |
| ApplicationUnavailable page = |
| (ApplicationUnavailable) cycle.getPage("ApplicationUnavailable"); |
| |
| String message = _applicationUnavailableMessage; |
| |
| if (message == null) |
| message = cause.getMessage(); |
| |
| if (message == null) |
| message = cause.getClass().getName(); |
| |
| page.activate(message, cause); |
| |
| cycle.activate(page); |
| |
| renderResponse(cycle, output); |
| } |
| catch (Throwable t) |
| { |
| super.activateExceptionPage(cycle, output, cause); |
| } |
| } |
| |
| /** |
| * Reads a person by id. |
| * |
| **/ |
| |
| public Person readPerson(Integer personId) |
| { |
| Person result = null; |
| |
| int i = 0; |
| while (true) |
| { |
| IOperations operations = getOperations(); |
| |
| try |
| { |
| result = operations.getPerson(personId); |
| |
| break; |
| } |
| catch (FinderException ex) |
| { |
| throw new ApplicationRuntimeException("No such Person #" + personId + ".", ex); |
| } |
| catch (RemoteException ex) |
| { |
| rmiFailure("Unable to read Person #" + personId + ".", ex, i++); |
| } |
| } |
| |
| return result; |
| } |
| |
| protected void handleStaleSessionException( |
| StaleSessionException ex, |
| IRequestCycle cycle, |
| ResponseOutputStream output) |
| throws IOException, ServletException |
| { |
| IMessageProperty home = (IMessageProperty)cycle.getPage("Home"); |
| |
| home.setMessage("You have been logged out due to inactivity."); |
| |
| redirect("Home", cycle, output, ex); |
| } |
| |
| } |
