WF提供了一种用于对所有支持数据输入的活动的、基于角色的访问机制。工作流创建者可以完全控制如何创建角色和角色集合。这样将使创建者能够提供必要的授权机制，在执行活动之前验证调用者的角色。比如WF中的WebServiceInputActivity 和 HandleExternalEventActivity活动。

WF中提供来两种方式：ActiveDirectoryRole(通过活动目录用户)和WebWorkflowRole(ASP.NET Role)。下面举例说明：

1.我们使用HandleExternalEventActivity活动来提供图书检索功能，当有人检索的时候会触发检索事件，只有会员才可以使用该功能。首先来定义事件参数：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Workflow.Activities;

namespace CaryWFRole
{
    [Serializable]
    public class BookEventArgs : ExternalDataEventArgs
    {
        public string ID { get; set; }
        public string Name { get; set; }
        public string Author { get; set; }

        public BookEventArgs()
            : base(Guid.NewGuid())
        { }

        public BookEventArgs(Guid instanceID, string id,
 string name, string author)
            : base(instanceID)
        {
            this.ID = id;
            this.Name = name;
            this.Author = author;
        }
    }
}

2.事件接口如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Workflow.Activities;

namespace CaryWFRole
{
    [ExternalDataExchangeAttribute()]
    public interface ISearchBookService
    {
        event EventHandler<BookEventArgs> SearchBook;
    }
}

3.实现该接口，代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Principal;

namespace CaryWFRole
{
    public class SearchBookService:ISearchBookService
    {
        public event EventHandler<BookEventArgs> SearchBook;

        public void OnSearchRequest(Guid instanceId,
 string id,string name,string author, IIdentity identity)
        {
            BookEventArgs args = new BookEventArgs
(instanceId, id, name, author);
            String securityIdentifier = null;
            WindowsIdentity windowsIdentity = 
identity as WindowsIdentity;

            if (windowsIdentity != null && 
windowsIdentity.User != null)
                securityIdentifier = 
windowsIdentity.User.Translate(typeof(NTAccount)).ToString();
            else if (identity != null)
                securityIdentifier = identity.Name;

            args.Identity = securityIdentifier;
            Console.WriteLine("return book by: {0}", identity.Name);

            if (SearchBook != null)
                SearchBook(null, args);
        }
    }
}

4.工作流设计如下：

通过设置检索事件（HandleExternalEventActivity）活动的的Roles属性来控制，只有该角色集合的用户才有权限。在工作流中我们只允许会员才可以做
检索，代码如下：

using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Collections;
using System.Drawing;
using System.Linq;
using System.Workflow.ComponentModel.Compiler;
using System.Workflow.ComponentModel.Serialization;
using System.Workflow.ComponentModel;
using System.Workflow.ComponentModel.Design;
using System.Workflow.Runtime;
using System.Workflow.Activities;
using System.Workflow.Activities.Rules;

namespace CaryWFRole
{
    public sealed partial class BookWorkflow :
 SequentialWorkflowActivity
    {
        public BookWorkflow()
        {
            InitializeComponent();
        }

        private WorkflowRoleCollection sAllowRoles = 
new WorkflowRoleCollection();

        public WorkflowRoleCollection AllowRoles
        {
            get { return sAllowRoles; }
        }

        private void codeActivity1_ExecuteCode
(object sender, EventArgs e)
        {
            WebWorkflowRole role = new WebWorkflowRole("会员");
            AllowRoles.Add(role);
        }

        private void handleExternalEventActivity1_
Invoked(object sender, ExternalDataEventArgs e)
        {
            Console.WriteLine("查询成功");
        }
    }
}

5.通过如下函数来创建角色和用户，代码如下：

static void CreateRoles()
{
     if (!System.Web.Security.Roles.RoleExists("会员"))
     {
         System.Web.Security.Roles.CreateRole("会员");
         string[] users = { "张三", "李四", "王五" };
         string[] ClerkRole = { "会员" };
         System.Web.Security.Roles.
AddUsersToRoles(users, ClerkRole);
     }           
}

6.假设以张三的身份来检索，触发事件的函数如下：

static void SendSearchRequest()
{
       try
       {                
            string id = "001";
            string name = "C#高级编程";
            string author = "某某某";
                
            GenericIdentity genIdentity = 
new GenericIdentity("张三");
            sBook.OnSearchRequest
(workflowInstanceId, id, name, author, genIdentity);
       }
       catch (Exception e)
       {
            Console.WriteLine("Exception message: {0}", e.ToString());
       }
}

7.宿主程序如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Workflow.Runtime;
using System.Workflow.Runtime.Hosting;
using System.Security.Principal;
using System.Workflow.Activities;

namespace CaryWFRole
{
    class Program
    {
        static SearchBookService sBook;
        static Guid workflowInstanceId;
        static AutoResetEvent waitHandle =
 new AutoResetEvent(false);

        static void Main()
        {
            CreateRoles();
            using (WorkflowRuntime workflowRuntime =
 new WorkflowRuntime())
            {
                workflowRuntime.StartRuntime();
                Type type = typeof(BookWorkflow);
                ExternalDataExchangeService dataService =
 new ExternalDataExchangeService();
                workflowRuntime.AddService(dataService);

                sBook = new SearchBookService();
                dataService.AddService(sBook);

                workflowRuntime.WorkflowCompleted +=
 OnWorkflowCompleted;
                workflowRuntime.WorkflowTerminated +=
 OnWorkflowTerminated;

                WorkflowInstance instance = 
workflowRuntime.CreateWorkflow(type);
                workflowInstanceId = instance.InstanceId;
                instance.Start();
                SendSearchRequest();
                waitHandle.WaitOne();
                workflowRuntime.StopRuntime();
            }
        }

        static void OnWorkflowCompleted(object sender, 
WorkflowCompletedEventArgs e)
        {
            waitHandle.Set();
        }
        static void OnWorkflowTerminated(object sender,
 WorkflowTerminatedEventArgs e)
        {
            Console.WriteLine(e.Exception.Message);
            waitHandle.Set();
        }
    }
}

8.我们要配置aspnetdb数据库，app.config如下：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="SqlServerConnection"
             connectionString="Integrated Security =
 SSPI;server=.;database=aspnetdb" />
    </connectionStrings>
    <system.web>
        <roleManager enabled="true" defaultProvider=
"SqlProvider">
            <providers>
                <add name="SqlProvider" connectionStringName=
"SqlServerConnection" 
                applicationName="ConsoleAppSample" type=
"System.Web.Security.SqlRoleProvider, 
                System.Web, Version=2.0.3600.0, 
Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
            </providers>
        </roleManager>
    </system.web>
</configuration>

9.执行结果如下：