WCF开发日志 -- OEA里面的WCF设计

一、摘要

场景： 

      最近公司的项目中用到了WCF 就想着分析OEA里的WCF设计，吸取一下高手的经验 。

类图：

       今天在这里主要是分析OEA里的WCF设计(也叫分布式业务对象数据门户)。先看一下OEA类库

      

二、本文大纲

       a、摘要 。

       b、本文大纲 。

       c、WCF接口设计。

       d、WCF 交互设计 。

       e、数据门户设计 。

       f、业务对象知识补充 。

三、WCF接口设计

关于WCF接口的相关知识可以看以前写WCF 开发日志 -- WCF契约设计

 

消息契约(MessageContract)  在 WCF 开发日志 -- WCF契约设计 有提到一点，在网上和MSDN上有更详细的说明了，这里就不详细描述了。

WcfResponse , FetchRequest , UpdateRequest 

上面类图对应有三个文件，其实这三个文件的内容都差不多，只是职责不同。

 

四、WCF 交互设计

服务端实现：

 红色部分就是WCF适配到数据门户来进行与数据库交互否实现业务逻辑。

 1:  /// <summary>

 2:    /// 使1用?WCF实现的统一的数据门户

 3:    /// 

 4:    /// 标记了ConcurrencyMode.Multiple 来表示多线程进行

 5:    /// </summary>

 6:    [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall, ConcurrencyMode = ConcurrencyMode.Multiple, UseSynchronizationContext = false)]

 7:    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]

 8:    public class WcfPortal : IWcfPortal

 9:    {

10:        /// <summary>

11:        /// Get an existing business object.

12:        /// </summary>

13:        /// <param name="request">The request parameter object.</param>

14:        public WcfResponse Fetch(FetchRequest request)

15:        {

16:            

27:        }

28:   

29:        /// <summary>

30:        /// Update a business object.

31:        /// </summary>

32:        /// <param name="request">The request parameter object.</param>

33:        public WcfResponse Update(UpdateRequest request)

34:        {

35:            

46:        }

47:    }

48:   

 

客服端直接使用WCF的代理类ChannelFactory实现

  1:  /// <summary>

  2:      /// Implements a data portal proxy to relay data portal

  3:      /// calls to a remote application server by using WCF.

  4:      /// </summary>

  5:      public class WcfProxy : OEA.DataPortalClient.IDataPortalProxy，
    
     IDataPortalServer
    

  6:      {

  7:          #region IDataPortalProxy Members

  8:   

  9:          /// <summary>

 10:          /// Gets a value indicating whether the data portal

 11:          /// is hosted on a remote server.

 12:          /// </summary>

 13:          public bool IsServerRemote

 14:          {

 15:              get { return true; }

 16:          }

 17:   

 18:          #endregion

 19:  

 20:          #region IDataPortalServer Members

 21:   

 22:          private string _endPoint = "WcfDataPortal";

 23:   

 24:          /// <summary>

 25:          /// Gets or sets the WCF endpoint used

 26:          /// to contact the server.

 27:          /// </summary>

 28:          /// <remarks>

 29:          /// The default value is WcfDataPortal.

 30:          /// </remarks>

 31:          protected string EndPoint

 32:          {

 33:              get

 34:              {

 35:                  return _endPoint;

 36:              }

 37:              set

 38:              {

 39:                  _endPoint = value;

 40:              }

 41:          }

 42:   

 43:          /// <summary>

 44:          /// Returns an instance of the channel factory

 45:          /// used by GetProxy() to create the WCF proxy

 46:          /// object.

 47:          /// </summary>

 48:          protected virtual ChannelFactory<IWcfPortal> GetChannelFactory()

 49:          {

 50:              return new ChannelFactory<IWcfPortal>(_endPoint);

 51:          }

 52:   

 53:          /// <summary>

 54:          /// Returns the WCF proxy object used for

 55:          /// communication with the data portal

 56:          /// server.

 57:          /// </summary>

 58:          /// <param name="cf">

 59:          /// The ChannelFactory created by GetChannelFactory().

 60:          /// </param>

 61:          protected virtual IWcfPortal GetProxy(ChannelFactory<IWcfPortal> cf)

 62:          {

 63:              return cf.CreateChannel();

 64:          }

 65:   

 66:          /// <summary>

 67:          /// Called by <see cref="DataPortal" /> to load an

 68:          /// existing business object.

 69:          /// </summary>

 70:          /// <param name="objectType">Type of business object to create.</param>

 71:          /// <param name="criteria">Criteria object describing business object.</param>

 72:          /// <param name="context">

 73:          /// <see cref="Server.DataPortalContext" /> object passed to the server.

 74:          /// </param>

 75:          public DataPortalResult Fetch(Type objectType, object criteria, DataPortalContext context)

 76:          {

 77:              ChannelFactory<IWcfPortal> cf = GetChannelFactory();

 78:              IWcfPortal svr = GetProxy(cf);

 79:              WcfResponse response = null;

 80:              try

 81:              {

 82:                  response =

 83:                         svr.Fetch(new FetchRequest(objectType, criteria, context));

 84:                  if (cf != null)

 85:                      cf.Close();

 86:              }

 87:              catch

 88:              {

 89:                  cf.Abort();

 90:                  throw;

 91:              }

 92:   

 93:              object result = response.Result;

 94:              if (result is Exception)

 95:                  throw (Exception)result;

 96:              return (DataPortalResult)result;

 97:          }

 98:   

 99:          /// <summary>

100:          /// Called by <see cref="DataPortal" /> to update a

101:          /// business object.

102:          /// </summary>

103:          /// <param name="obj">The business object to update.</param>

104:          /// <param name="context">

105:          /// <see cref="Server.DataPortalContext" /> object passed to the server.

106:          /// </param>

107:          public DataPortalResult Update(object obj, DataPortalContext context)

108:          {

109:              ChannelFactory<IWcfPortal> cf = GetChannelFactory();

110:              IWcfPortal svr = GetProxy(cf);

111:              WcfResponse response = null;

112:              try

113:              {

114:                  response =

115:                        svr.Update(new UpdateRequest(obj, context));

116:                  if (cf != null)

117:                      cf.Close();

118:              }

119:              catch

120:              {

121:                  cf.Abort();

122:                  throw;

123:              }

124:   

125:   

126:              object result = response.Result;

127:              if (result is Exception)

128:                  throw (Exception)result;

129:              return (DataPortalResult)result;

130:          }

131:   

132:          #endregion

133:      }

134:   

 

IWcfPortal接口 和 IDataPortalServer接口 介绍  其实这两个接口都提供了 Fetch Update

 1:  /// <summary>

 2:     /// Defines the service contract for the WCF data

 3:     /// portal.

 4:     /// </summary>

 5:     [ServiceContract(Namespace = "http://ws.lhotka.net/WcfDataPortal")]

 6:     public interface IWcfPortal

 7:     {

 8:         /// <summary>

 9:         /// Get an existing business object.

10:         /// </summary>

11:         /// <param name="request">The request parameter object.</param>

12:         [OperationContract]

13:         [UseNetDataContract]

14:         WcfResponse Fetch(FetchRequest request);

15:   

16:         /// <summary>

17:         /// Update a business object.

18:         /// </summary>

19:         /// <param name="request">The request parameter object.</param>

20:         [OperationContract]

21:         [UseNetDataContract]

22:         WcfResponse Update(UpdateRequest request);

23:     }

24:   

IDataPortalServer

 1:  /// <summary>

 2:     /// Interface implemented by server-side data portal

 3:     /// components.

 4:     /// </summary>

 5:     public interface IDataPortalServer

 6:     {

 7:         /// <summary>

 8:         /// Get an existing business object.

 9:         /// </summary>

10:         /// <param name="objectType">Type of business object to retrieve.</param>

11:         /// <param name="criteria">Criteria object describing business object.</param>

12:         /// <param name="context">

13:         /// <see cref="Server.DataPortalContext" /> object passed to the server.

14:         /// </param>

15:         DataPortalResult Fetch(Type objectType, object criteria, DataPortalContext context);

16:   

17:         /// <summary>

18:         /// Update a business object.

19:         /// </summary>

20:         /// <param name="obj">Business object to update.</param>

21:         /// <param name="context">

22:         /// <see cref="Server.DataPortalContext" /> object passed to the server.

23:         /// </param>

24:         DataPortalResult Update(object obj, DataPortalContext context);

25:     }

26:   

 

事实上这两个接口都提供了 Fetch Update 都是操作数据门户的，不过一个是服务端，一个是客服端所以实现方式上也有点不同。

 

五、数据门户设计

DataPortalFacade 数据门户外观模式 也是实现IDataPortalServer接口,主要是权限的就是上下文的实现（ApplicationContext）。

 

DataPortalContext 数据上下文没有实现IDataPortalServer接口

 最终的数据门户

 1:  /// <summary>

 2:  /// Implements the server-side DataPortal as discussed

 3:  /// in Chapter 4.

 4:  /// </summary>

 5:  public class FinalDataPortal : IDataPortalServer

 6:  {

 7:      /// <summary>

 8:      /// Get an existing business object.

 9:      /// </summary>

10:      /// <param name="objectType">Type of business object to retrieve.</param>

11:      /// <param name="criteria">Criteria object describing business object.</param>

12:      /// <param name="context">

13:      /// <see cref="Server.DataPortalContext" /> object passed to the server.

14:      /// </param>

15:      public DataPortalResult Fetch(Type objectType, object criteria, DataPortalContext context)

16:      {

17:          // create an instance of the business object.

18:          var obj = Activator.CreateInstance(objectType, true);

19:   

20:          MethodCaller.CallMethodIfImplemented(obj, "QueryBy", criteria);

21:   

22:          // return the populated business object as a result

23:          return new DataPortalResult(obj);

24:      }

25:   

26:      /// <summary>

27:      /// Update a business object.

28:      /// </summary>

29:      /// <param name="obj">Business object to update.</param>

30:      /// <param name="context">

31:      /// <see cref="Server.DataPortalContext" /> object passed to the server.

32:      /// </param>

33:      public DataPortalResult Update(object obj, DataPortalContext context)

34:      {

35:          // tell the business object to update itself

36:          var target = obj as Entity;

37:          if (target != null)

38:          {

39:              target.SaveRoot();

40:          }

41:          else if (obj is Service)

42:          {

43:              (obj as Service).ExecuteByDataPortal();

44:          }

45:          else if (obj is EntityList)

46:          {

47:              (obj as EntityList).SaveRootList();

48:          }

49:          else

50:          {

51:              // this is an updatable collection or some other

52:              // non-BusinessBase type of object

53:              // tell the object to update itself

54:              MethodCaller.CallMethodIfImplemented(obj, "DataPortal_Update");

55:          }

56:   

57:          return new DataPortalResult(obj);

58:      }

59:  }

60:   

 

代码约定（实体列表类需要编写对应类型的 QueryBy 数据层方法完成数据访问逻辑）也就是每一个业务对象集合都的实现QueryBy方法。 在代码里没有找到不知道作者是这么实现的。纠结中........

 

六、业务对象知识补充

说起业务对象就不的不说一下业务对象的三要素了，如下来51CTO网站上的图片

■ 标识（identity），是唯一区别其他对象的标志；

■ 状态（state），描述对象所蕴含的信息；

■ 行为（behavior），对象所持有的、描述对象如何被使用的方法。

关于业务对象的理论这里有园里有一篇就将的很全面了，这里就不做补充了，大家有兴趣可以直接看作者的这篇：关于业务对象本质的思考（1）的文章。

以下是OEA的实体对象状态抽象:

以下是对象状态的实现 也就是Entity.Csla.cs  类的代码了：

  1:  /// <summary>

  2:   /// 原-来′ Csla 中D的? BusinessBase 中D的?代ú码?，?都?移?动ˉ到?这a个?类à中D。￡

  3:   /// </summary>

  4:   public abstract partial class Entity 

  5:   {

  6:       #region PersistenceStatus

  7:   

  8:       [NonSerialized]

  9:       private PersistenceStatus _previousStatusBeforeDeleted = PersistenceStatus.Unchanged;

 10:       private PersistenceStatus _status = PersistenceStatus.New;

 11:   

 12:       public PersistenceStatus Status

 13:       {

 14:           get { return this._status; }

 15:           set

 16:           {

 17:               if (value != this._status)

 18:               {

 19:                   if (value == PersistenceStatus.Deleted)

 20:                   {

 21:                       this._previousStatusBeforeDeleted = this._status;

 22:                   }

 23:   

 24:                   this._status = value;

 25:               }

 26:           }

 27:       }

 28:   

 29:       public bool IsNew

 30:       {

 31:           get { return this.Status == PersistenceStatus.New; }

 32:       }

 33:   

 34:       public bool IsDeleted

 35:       {

 36:           get { return this.Status == PersistenceStatus.Deleted; }

 37:       }

 38:   

 39:       public void MarkNew()

 40:       {

 41:           this.Status = PersistenceStatus.New;

 42:       }

 43:   

 44:       public void MarkDirty()

 45:       {

 46:           if (this.Status != PersistenceStatus.New)

 47:           {

 48:               this.Status = PersistenceStatus.Modified;

 49:           }

 50:       }

 51:   

 52:       public virtual void MarkDeleted()

 53:       {

 54:           this.Status = PersistenceStatus.Deleted;

 55:       }

 56:   

 57:       public void RevertDeleted()

 58:       {

 59:           this._status = this._previousStatusBeforeDeleted;

 60:       }

 61:   

 62:       protected void MarkModified()

 63:       {

 64:           if (this.Status == PersistenceStatus.Unchanged) { this.Status = PersistenceStatus.Modified; }

 65:       }

 66:   

 67:       #endregion

 68:  

 69:       #region IDirtyAware

 70:   

 88:       public virtual bool IsSelfDirty

 89:       {

 90:           get { return this.Status != PersistenceStatus.Unchanged; }

 91:       }

 92:   

 93:       public virtual void MarkOld()

 94:       {

 95:           this.Status = PersistenceStatus.Unchanged;

 96:   

 97:           foreach (var field in this.GetNonDefaultPropertyValues())

 98:           {

 99:               var value = field.Value as IDirtyAware;

100:               if (value != null && value.IsDirty) value.MarkOld();

101:           }

102:       }

103:   

104:       #endregion

105: 

154:       /// <summary>

155:       /// 这个事件不可以屏敝，否则状态会出问题

156:       /// </summary>

157:       /// <param name="e"></param>

158:       protected override void OnPropertyChanged(IManagedPropertyChangedEventArgs e)

159:       {

160:           if (e.Source != ManagedPropertyChangedSource.FromPersistence)

161:           {

162:               this.MarkModified();

163:           }

164:   

165:           base.OnPropertyChanged(e);

166:       }

167:   

254:   }

255:   

 

在那里使用了对象状态?

 

七、总结

 

 

 

 

 

 

 

 

这里主要是学到了什么是业务对象，WCF接口设计，服务实现，代理，.NET数据上下文的实现。

整体设计图纸：

不懂之处：DataPortal_Update没有找到,对象状态不知道在那里使用，还是说客服端传过来的？

技术不足之处，对数据上下文的理解。