MonoRail/Castle.MonoRail.Framework/Extensions/Session/CustomSessionExtension.cs

   1 // Copyright 2004-2007 Castle Project - http://www.castleproject.org/
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 namespace Castle.MonoRail.Framework.Extensions.Session
  16 {
  17         using System;
  18         using System.Xml;
  19         using System.Collections;
  20         using System.Configuration;
  21         using Castle.Core.Configuration;
  22         using Castle.MonoRail.Framework.Configuration;
  23
  24         /// <summary>
  25         /// This extension allow one to provide a custom
  26         /// implementation of the session available on <see cref="IEngineContext"/>
  27         /// </summary>
  28         /// <remarks>
  29         /// To successfully install this extension you must add the attribute <c>customSession</c>
  30         /// to the <c>monoRail</c> configuration node and register the extension on the extensions node.
  31         /// <code>
  32         ///   &lt;monoRail customSession="Type name that implements ICustomSessionFactory"&gt;
  33         ///     &lt;extensions&gt;
  34         ///       &lt;extension type="Castle.MonoRail.Framework.Extensions.Session.CustomSessionExtension, Castle.MonoRail.Framework" /&gt;
  35         ///     &lt;/extensions&gt;
  36         ///   &lt;/monoRail&gt;
  37         /// </code>
  38         /// </remarks>
  39         public class CustomSessionExtension : IMonoRailExtension
  40         {
  41                 /// <summary>
  42                 /// Reference to an instance of <see cref="ICustomSessionFactory"/>
  43                 /// obtained from the configuration
  44                 /// </summary>
  45                 private ICustomSessionFactory customSession;
  46
  47                 #region IMonoRailExtension implementation
  48
  49                 /// <summary>
  50                 /// Gives to the extension implementor a chance to read
  51                 /// attributes and child nodes of the extension node
  52                 /// </summary>
  53                 /// <param name="node">The node that defines the MonoRail extension</param>
  54                 public void SetExtensionConfigNode(IConfiguration node)
  55                 {
  56                         // Ignored
  57                 }
  58
  59                 #endregion
  60
  61                 #region IServiceEnabledComponent implementation
  62
  63                 /// <summary>
  64                 /// Services the specified provider.
  65                 /// </summary>
  66                 /// <param name="provider">The provider.</param>
  67                 public void Service(IMonoRailServices provider)
  68                 {
  69                         ExtensionManager manager = (ExtensionManager) provider.GetService(typeof(ExtensionManager));
  70                         IMonoRailConfiguration config = (IMonoRailConfiguration) provider.GetService(typeof(IMonoRailConfiguration));
  71
  72                         Init(manager, config);
  73                 }
  74
  75                 #endregion
  76
  77                 /// <summary>
  78                 /// Reads the attribute <c>customSession</c>
  79                 /// from <see cref="MonoRailConfiguration"/> and
  80                 /// instantiate it based on the type name provided.
  81                 /// </summary>
  82                 /// <exception cref="ConfigurationException">
  83                 /// If the typename was not provided or the type
  84                 /// could not be instantiated/found
  85                 /// </exception>
  86                 /// <param name="manager">The Extension Manager</param>
  87                 /// <param name="configuration">The configuration</param>
  88                 private void Init(ExtensionManager manager, IMonoRailConfiguration configuration)
  89                 {
  90                         manager.AcquireSessionState += OnAdquireSessionState;
  91                         manager.ReleaseSessionState += OnReleaseSessionState;
  92
  93                         string customSessionAtt =
  94                                 configuration.ConfigurationSection.Attributes["customSession"];
  95
  96                         if (customSessionAtt == null)
  97                         {
  98                                 String message = "The CustomSessionExtension requires that " +
  99                                                  "the type that implements ICustomSessionFactory be specified through the " +
 100                                                  "'customSession' attribute on 'monorail' configuration node";
 101                                 throw new ConfigurationErrorsException(message);
 102                         }
 103
 104                         Type customSessType = TypeLoadUtil.GetType(customSessionAtt);
 105
 106                         if (customSessType == null)
 107                         {
 108                                 String message = "The Type for the custom session could not be loaded. " +
 109                                                  customSessionAtt;
 110                                 throw new ConfigurationErrorsException(message);
 111                         }
 112
 113                         try
 114                         {
 115                                 customSession = (ICustomSessionFactory) Activator.CreateInstance(customSessType);
 116                         }
 117                         catch(InvalidCastException)
 118                         {
 119                                 String message = "The Type for the custom session must " +
 120                                                  "implement ICustomSessionFactory. " + customSessionAtt;
 121                                 throw new ConfigurationErrorsException(message);
 122                         }
 123                 }
 124
 125                 /// <summary>
 126                 /// Overrides the ISession instance on <see cref="IEngineContext"/>.
 127                 /// </summary>
 128                 /// <remarks>
 129                 /// Note that the session available through IHttpContext is left untouched</remarks>
 130                 /// <param name="context"></param>
 131                 private void OnAdquireSessionState(IEngineContext context)
 132                 {
 133                         IDictionary session = customSession.ObtainSession(context);
 134
 135                         context.Session = session;
 136                 }
 137
 138                 /// <summary>
 139                 /// Retrives the ISession instance from <see cref="IEngineContext"/>.
 140                 /// and invokes <see cref="ICustomSessionFactory.PersistSession"/>
 141                 /// </summary>
 142                 private void OnReleaseSessionState(IEngineContext context)
 143                 {
 144                         customSession.PersistSession(context.Session, context);
 145                 }
 146         }
 147 }