使用Apworks开发基于CQRS架构的应用程序（五）：命令

客户端程序通过命令告知系统“应该做什么”。事实上，这是一种单向的交互过程，客户端程序仅仅向领域模型发送命令请求，它们并不会通过领域模型来查询某些数据信息。在CQRS架构的应用程序中，“查询”是另一部分的内容，这将在接下来的章节中单独讨论。当应用服务器端接收到来自客户端的命令请求后，就会将这些命令推送到命令总线。命令处理器会侦听命令总线，并相应地处理命令请求。现在，让我们在TinyLibraryCQRS解决方案中创建命令与命令解释器。

1. 右键单击TinyLibraryCQRS解决方案，单击 Add | New Project… 菜单，这将打开Add New Project对话框
2. 在Installed Templates选项卡下，选择Visual C# | Windows，然后选择Class Library，确保所选的.NET版本是.NET Framework 4，然后在Name文本框中，输入TinyLibrary.Commands，并单击OK按钮
3. 在TinyLibrary.Commands项目上，右键单击References节点，单击Add Reference…菜单，这将打开Add Reference对话框
4. 在.NET选项卡下，选择Apworks，然后单击OK按钮
5. 添加下面的代码：
   

   using System;

   using Apworks.Commands;

      3:  

   namespace TinyLibrary.Commands

      5: {

      6:     [Serializable]

   class BorrowBookCommand : Command

      8:     {

   long ReaderId { get; set; }

   long BookId { get; set; }

     11:  

   long bookId)

     13:         {

   this.ReaderId = readerId;

   this.BookId = bookId;

     16:         }

     17:     }

     18:  

     19:     [Serializable]

   class CreateBookCommand : Command

     21:     {

   private set; }

   private set; }

   private set; }

   private set; }

   private set; }

   private set; }

     28:  

   string title, 

   string publisher, 

     31:             DateTime pubDate, 

   bool lent)

     33:         {

   this.Title = title;

   this.PubDate = pubDate;

   this.Publisher = publisher;

   this.ISBN = isbn;

   this.Pages = pages;

   this.Lent = lent;

     40:         }

     41:  

   long id, 

   string title, 

   string publisher, 

     45:             DateTime pubDate, 

   bool lent)

   base(id)

     48:         {

   this.Title = title;

   this.PubDate = pubDate;

   this.Publisher = publisher;

   this.ISBN = isbn;

   this.Pages = pages;

   this.Lent = lent;

     55:         }

     56:     }

     57:  

     58:     [Serializable]

   class RegisterReaderCommand : Command

     60:     {

   private set; }

   private set; }

     63:  

   string name)

     65:         {

   this.LoginName = loginName;

   this.Name = name;

     68:         }

     69:  

   base(id)

     71:         {

   this.LoginName = loginName;

   this.Name = name;

     74:         }

     75:     }

     76:  

     77:     [Serializable]

   class ReturnBookCommand : Command

     79:     {

   long ReaderId { get; set; }

   long BookId { get; set; }

     82:  

   long bookId)

     84:         {

   this.ReaderId = readerId;

   this.BookId = bookId;

     87:         }

     88:     }

     89: }