在ASP.NET MVC中使用WF

本文是基于ASP.NET MVC的beta版本。
1.我们首先建立一个ASP.NET MVC的应用程序。在web.config中将下面的配置添加到相关位置，代码如下:

<?xml version="1.0"?>
<configuration>
  <configSections>
   <section name="WorkflowRuntime" type="System.Workflow.Runtime.Configuration.
    WorkflowRuntimeSection,System.Workflow.Runtime, Version=3.0.00000.0, Culture=neutral,
    PublicKeyToken=31bf3856ad364e35"/>
  </configSections>
  <WorkflowRuntime Name="WorkflowServiceContainer">
    <Services>
     <add type="System.Workflow.Runtime.Hosting.ManualWorkflowSchedulerService,
       System.Workflow.Runtime,Version=3.0.0.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35"/>
     <add type="System.Workflow.Runtime.Hosting.DefaultWorkflowCommitWorkBatchService,
       System.Workflow.Runtime,Version=3.0.0.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35"/>
     <add type="System.Workflow.Runtime.Hosting.SqlWorkflowPersistenceService,
       System.Workflow.Runtime,Version=3.0.00000.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35"
       UnloadOnIdle="true" LoadIntervalSeconds="5" ConnectionString="Initial Catalog=
       WorkflowPersistence;Data Source=localhost\SQLEXPRESS;Integrated Security=SSPI;"/>
    </Services>
  </WorkflowRuntime>
  <appSettings/>
  <connectionStrings/>
  <system.web>
    <compilation debug="true">
      <assemblies>
        <add assembly="Accessibility,Version=2.0.0.0,Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.Workflow.Runtime, Version=3.0.0.0,Culture=neutral, 
                       PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Workflow.ComponentModel, Version=3.0.0.0,Culture=neutral, 
                       PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Workflow.Activities, Version=3.0.0.0,Culture=neutral,  
                       PublicKeyToken=31BF3856AD364E35"/>
       </assemblies>
    </compilation>
    <authentication mode="Windows"/>
  </system.web>
</configuration>

持久化服务在这个例子中你可以不必使用，但是真正的项目中是比不可少的。

2.然后在Global.asax.cs中的Application_Start()和Application_End分别启用和停止工作流引擎(WorkflowRuntime),
代码如下：

protected void Application_Start()
{
    RegisterRoutes(RouteTable.Routes);
    WorkflowRuntime workflowRuntime =new WorkflowRuntime("WorkflowRuntime");            
    workflowRuntime.StartRuntime();          
    Application["WorkflowRuntime"] = workflowRuntime;
}
void Application_End(object sender, EventArgs e)
{            
    WorkflowRuntime workflowRuntime =Application["WorkflowRuntime"] as WorkflowRuntime;
    workflowRuntime.StopRuntime();
}

3.我们来设计我们的视图，我们来完成一个加法运算，Index视图的相关代码如下：
 <p>
    <%Html.BeginForm("Compute","Home");%>
    <label>请输入第一个数字：</label><%=Html.TextBox("Number1") %><br />
    <label>请输入第二个数字：</label><%=Html.TextBox("Number2") %><br />
    <input type="submit" value="计算"></input><br/>
   <label>结果为：</label> <%=Html.Encode(ViewData["Result"]) %>
    <%Html.EndForm(); %>
 </p>
我们会在HomeControler的Compute Action中来调用WF来完成加法运算。

4.我们在看下HomeControler中的Compute Action，代码如下：

int Result = 0;

public ActionResult Compute()
{            
    ControllerContext cxt = this.ControllerContext;
    WorkflowRuntime workflowRuntime = cxt.HttpContext.Application["WorkflowRuntime"] 
                                      as WorkflowRuntime;
    ManualWorkflowSchedulerService scheduler =workflowRuntime.GetService(
            typeof(ManualWorkflowSchedulerService)) as ManualWorkflowSchedulerService;           
    workflowRuntime.WorkflowCompleted+= new EventHandler<WorkflowCompletedEventArgs>(
            workflowRuntime_WorkflowCompleted);            
    int Number1 = Int32.Parse(Request.Form["Number1"]);
    int Number2 = Int32.Parse(Request.Form["Number2"]);            
    Dictionary<String, Object> wfPara= new Dictionary<string, object>();
    wfPara.Add("Number1", Number1);
    wfPara.Add("Number2", Number2);            
    WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(CaryWFLib.AddWorkflow), 
                                wfPara);
    instance.Start();            
    scheduler.RunWorkflow(instance.InstanceId);
    ViewData["Result"]=Result;
    return View("Index");
}

void workflowRuntime_WorkflowCompleted(object sender, WorkflowCompletedEventArgs e)
{            
    if (e.OutputParameters.ContainsKey("Result"))
    {
        Result = (int)e.OutputParameters["Result"];                
    }
}

注：
4.1.在ASP.NET MVC中通过如下代码来得到Global.asax.cs中的Application对象：
ControllerContext cxt = this.ControllerContext; WorkflowRuntime workflowRuntime = cxt.HttpContext.Application["WorkflowRuntime"] as WorkflowRuntime;
4.2.我们调用我们的工作流时，要装载ManualWorkflowSchedulerService服务，这点非常重要.这样可以让工作流同步的执行在
ASP.NET MVC的线程上。如果不装载该服务工作流实例会异步的执行在由Workflow runtime管理的线程上。
4.3.我们通过调用工作流来完成加法运算，并将得到的结果ViewData["Result"]返回给视图Index。

5.然后我们来看看我们的WF程序，我们只在工作流设计器中拖入一个CodeActivity，用它来完成我们加法运算的逻辑，工作流的代码如下：

public sealed partial class AddWorkflow: SequentialWorkflowActivity
{
    public int Number1 { get; set; }
    public int Number2 { get; set; }
    public int Result { get; set; }

    public AddWorkflow()
    {
        InitializeComponent();
    }

    private void codeActivity1_ExecuteCode(object sender, EventArgs e)
    {
        Result = Number1 + Number2;
    }
}

6.整个项目完成后，项目结构如下图：

7.运行home/index后，我们输入两个数字，点击计算按钮会执行HomeControler的Compute Action，可以得到计算的结果，
如下图：