本文將介紹WF4 Beta 2中新功能特性，并通過WF4 Beta 2與WF4 Beta 1的對比，使大家能更好的了解WF4 Beta 2。

1. 取消了[WorkflowElement], 與WF3.0一樣,[Activity]成為了WF功能Activity的根類型

2. 增加了表達式Activity [ ActivityWithResult]

public sealed class wxwinterActivityResult :CodeActivity<string>   
{   
protected override string Execute(CodeActivityContext context)   
{   
return "wxwinter";   
}  

3. 增加了異步Activity [AsyncCodeActivity] 可以實現 Begin/End的異步執行方式

public sealed class wxwinterActivity : AsyncCodeActivity   
{   
protected override IAsyncResult BeginExecute(AsyncCodeActivityContext context, AsyncCallback callback, object state)   
{   
return callback.BeginInvoke(null, null, null);   
}   
protected override void EndExecute(AsyncCodeActivityContext context, IAsyncResult result)   
{   
}   
}  

4. 取消 [InvokePowershell] Activity

關于[InvokePowershell] Activity的介紹見我寫的WF4.0 Beta1 調用PowerShell

( http://www.cnblogs.com/foundation/archive/2009/06/28/1512542.html)

5. 添加Activity [Rethrow] 以實現再次引發異常

變化很大,基本上可以認為是兩個產品

class Program   
{   
static void Main(string[] args)   
{   
WorkflowApplication instance = new WorkflowApplication(new wxwinterActivity());   
instance.Run();   
System.Console.Read();   
}   
}   
public class wxwinterActivity : CodeActivity   
{   
protected override void Execute(CodeActivityContext context)   
{   
System.Console.WriteLine("wxd");   
}   
}  

WF4 Beta 2與WF4 Beta1的運行環境對比說明

流程實例 [WorkflowInstance] 被 [WorkflowApplication] 取代

class Program   
{   
static void Main(string[] args)   
{   
WorkflowInstance instance = new WorkflowInstance(new wxwinterActivity());   
instance.Run();   
System.Console.Read();   
}   
}   
public class wxwinterActivity : CodeActivity   
{   
protected override void Execute(CodeActivityContext context)   
{   
System.Console.WriteLine("wxd");   
}   
}  

WF3.X與WF4運行環境最明顯的變化是,在WF3.X中要創建實例要使用WorkflowRuntime的CreateWorkflow方法.

而在WF4中,不需要顯示創建一個[WorkflowRuntime],而是直接使用[WorkflowInstance (Beta1中)] 創建,這也是到了Beta2中將[WorkflowInstance ]改名為[WorkflowApplication]的原因

class Program   
{   
static void Main(string[] args)   
{   
WorkflowRuntime workflowRuntime = new WorkflowRuntime();   
WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(wxwinterActivity));   
instance.Start();   
System.Console.Read();   
}   
}   
public class wxwinterActivity : System.Workflow.ComponentModel.Activity   
{   
protected override System.Workflow.ComponentModel.ActivityExecutionStatus Execute(System.Workflow.ComponentModel.ActivityExecutionContext executionContext)   
{   
System.Console.WriteLine("wxd");   
return base.Execute(executionContext);   
}   
} 

WF4 Beta 2只提供了一個[Activity]的模板,

當使用個[Activity]的模板創建流程時,會提供一個只能放入一個控件的空環境

<Activity x:Class="ActivityLibrary1.wxwinterWorkFlow" mva:VisualBasic.Settings="Assembly references and imported namespaces serialized as XML namespaces" 
xmlns="http://schemas.microsoft.com/netfx/2009/xaml/activities" xmlns:mv="clr-namespace:Microsoft.VisualBasic;assembly=System" 
xmlns:mva="clr-namespace:Microsoft.VisualBasic.Activities;assembly=System.Activities" 
xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:s1="clr-namespace:System;assembly=System" 
xmlns:s2="clr-namespace:System;assembly=System.Xml" xmlns:s3="clr-namespace:System;assembly=System.Core" 
xmlns:scg="clr-namespace:System.Collections.Generic;assembly=System" xmlns:scg1="clr-namespace:System.Collections.Generic;assembly=System.ServiceModel" 
xmlns:scg2="clr-namespace:System.Collections.Generic;assembly=System.Core" xmlns:scg3="clr-namespace:System.Collections.Generic;assembly=mscorlib" 
xmlns:sd="clr-namespace:System.Data;assembly=System.Data" xmlns:sd1="clr-namespace:System.Data;assembly=System.Data.DataSetExtensions" 
xmlns:sl="clr-namespace:System.Linq;assembly=System.Core" xmlns:st="clr-namespace:System.Text;assembly=mscorlib" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">   
Activity>  

當向空Activity中放入[Sequence]時,就可認為是[順序工作流]

<Activity x:Class="ActivityLibrary1.wxwinterWorkFlow" 
mva:VisualBasic.Settings="Assembly references and imported namespaces serialized as XML namespaces" 
xmlns="http://schemas.microsoft.com/netfx/2009/xaml/activities" xmlns:mv="clr-namespace:Microsoft.VisualBasic;assembly=System" 
xmlns:mva="clr-namespace:Microsoft.VisualBasic.Activities;assembly=System.Activities" 
xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:s1="clr-namespace:System;assembly=System" 
xmlns:s2="clr-namespace:System;assembly=System.Xml" xmlns:s3="clr-namespace:System;assembly=System.Core" 
xmlns:scg="clr-namespace:System.Collections.Generic;assembly=System" xmlns:scg1="clr-namespace:System.Collections.Generic;assembly=System.ServiceModel" 
xmlns:scg2="clr-namespace:System.Collections.Generic;assembly=System.Core" xmlns:scg3="clr-namespace:System.Collections.Generic;assembly=mscorlib" 
xmlns:sd="clr-namespace:System.Data;assembly=System.Data" xmlns:sd1="clr-namespace:System.Data;assembly=System.Data.DataSetExtensions" 
xmlns:sl="clr-namespace:System.Linq;assembly=System.Core" xmlns:st="clr-namespace:System.Text;assembly=mscorlib" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">   
Activity>  

當向空Activity中放入[Flowchart]時,就可認為是[Flowchart工作流]

<Activity mc:Ignorable="sap" x:Class="ActivityLibrary1.wxwinterWorkFlow" mva:VisualBasic.Settings="Assembly references and imported namespaces serialized as XML namespaces" 
xmlns="http://schemas.microsoft.com/netfx/2009/xaml/activities" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
xmlns:mv="clr-namespace:Microsoft.VisualBasic;assembly=System" xmlns:mva="clr-namespace:Microsoft.VisualBasic.Activities;assembly=System.Activities" 
xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:s1="clr-namespace:System;assembly=System" xmlns:s2="clr-namespace:System;assembly=System.Xml" 
xmlns:s3="clr-namespace:System;assembly=System.Core" xmlns:sad="clr-namespace:System.Activities.Debugger;assembly=System.Activities" 
xmlns:sap="http://schemas.microsoft.com/netfx/2009/xaml/activities/presentation" xmlns:scg="clr-namespace:System.Collections.Generic;assembly=System" 
xmlns:scg1="clr-namespace:System.Collections.Generic;assembly=System.ServiceModel" xmlns:scg2="clr-namespace:System.Collections.Generic;assembly=System.Core" 
xmlns:scg3="clr-namespace:System.Collections.Generic;assembly=mscorlib" xmlns:sd="clr-namespace:System.Data;assembly=System.Data" 
xmlns:sd1="clr-namespace:System.Data;assembly=System.Data.DataSetExtensions" xmlns:sl="clr-namespace:System.Linq;assembly=System.Core" 
xmlns:st="clr-namespace:System.Text;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">   
<Sequence sad:XamlDebuggerXmlReader.FileName="d:\users\wxd\documents\visual studio 2010\Projects\ActivityLibrary1\ActivityLibrary1\wxwinterWorkFlow.xaml" 
sap:VirtualizedContainerService.HintSize="235,288">   
<sap:WorkflowViewStateService.ViewState>   
<scg3:Dictionary x:TypeArguments="x:String, x:Object">   
<x:Boolean x:Key="IsExpanded">Truex:Boolean>   
scg3:Dictionary>   
sap:WorkflowViewStateService.ViewState>   
<WriteLine sap:VirtualizedContainerService.HintSize="213,62" />   
<WriteLine sap:VirtualizedContainerService.HintSize="213,62" />   
Sequence>   
Activity>  

WF4 Beta1 非常鮮明的提供了兩個工作流模板[Flowchart工作流], [順序工作流]

[順序工作流]

[Flowchart工作流]

WF3.0/3.5也提供了兩個工作流模板[狀態機工作流], [順序工作流]

其中[狀態機工作流]與[Flowchart工作流]有相似之處

[狀態機工作流]

[順序工作流]

WF4 的工作流可以是用代碼構建的,也可以是由xaml構建的, xaml可以動態/靜態的編譯為一個類,也可以直接以字符串方式加載

WF3.X的工作流可以是用代碼構建的,也可以是由xoml構建的,帶class頭的xoml可以動態/靜態的編譯為一個類,沒有class頭的xoml可以直接以字符串方式加載

WF4與WF3.5都提供了持久化,跟蹤,通訊,阻塞等功能,但實現方式不同,也不通用.

WF4與WF3.5的流程設計器從UI風格與實現方式上也有很大不同

原文標題：WF4 Beta 2

鏈接：http://www.cnblogs.com/foundation/archive/2009/10/22/1587798.html

【編輯推薦】

1. 淺談WF 4.0 Beta1中的 跟蹤機制
2. WF4.0 Beta1中的規則引擎變化
3. 淺談WF 4.0 beta1的跟蹤配置
4. 詳解工作流架構與實現
5. 解析UML工作流管理系統