通过

如何创建和运行长时间运行的工作流

  • 项目

Windows Workflow Foundation (WF) 的一个主要功能就是运行时能够在数据库中持久保存和卸载空闲的工作流。 如何：运行工作流中的步骤演示了使用控制台应用程序进行工作流承载的基本知识。 示例演示了启动工作流、工作流生命周期处理程序和恢复书签。 为了有效演示工作流持久性，需要一个支持启动和恢复多个工作流实例的更为复杂的工作流主机。 教程中此步骤演示了如何创建 Windows 窗体主机应用程序，此 Windows 窗体主机应用程序支持启动和恢复多个工作流实例、工作流持久性，并为高级功能（如在后续教程步骤中演示的跟踪和版本控制）提供基础。

注意

教程中的这一个步骤和后续的步骤使用了如何：创建工作流中所有三个工作流类型。

创建持久性数据库

  1. 打开 SQL Server Management Studio 并连接到本地服务器，例如 .\SQLEXPRESS。 右键单击本地服务器上的“数据库”节点，然后选择“新建数据库”。 将新数据库命名为 WF45GettingStartedTutorial，接受所有其他值，然后选择“确定”。

    注意

    在创建数据库前，确保你在本地服务器上具有创建数据库权限。

  2. 从“文件”菜单中依次选择“打开”和“文件”。 浏览到以下文件夹：C:\Windows\Microsoft.NET\Framework\v4.0.30319\sql\en

    选择以下两个文件，然后单击“打开”。

    • SqlWorkflowInstanceStoreLogic.sql

    • SqlWorkflowInstanceStoreSchema.sql

  3. 从“窗口”菜单选择“SqlWorkflowInstanceStoreSchema.sql”。 确保在“可用数据库”下拉列表中选择“WF45GettingStartedTutorial”，然后从“查询”菜单中选择“执行”。

  4. 从“窗口”菜单中选择“SqlWorkflowInstanceStoreLogic.sql”。 确保在“可用数据库”下拉列表中选择“WF45GettingStartedTutorial”，然后从“查询”菜单中选择“执行”。

    警告

    请务必按正确顺序执行前面两个步骤。 如果不按顺序执行查询，系统会发生错误，并且持久性数据库会配置不正确。

添加对 DurableInstancing 程序集的引用

  1. 在解决方案资源管理器中右键单击“NumberGuessWorkflowHost”，然后选择“添加引用”。

  2. 从“添加引用”列表中选择“程序集”，然后在“搜索程序集”框中键入 DurableInstancing。 这将筛选程序集，使您更易于选择所需引用。

  3. 从“搜索结果”列表中选中“System.Activities.DurableInstancing”和“System.Runtime.DurableInstancing”旁边的复选框，然后单击“确定”。

创建工作流主机窗体

  1. 右键单击解决方案资源管理器中的“NumberGuessWorkflowHost”，然后依次选择“添加”、“新建项目”。

  2. 在“已安装”模板列表中，选择“Windows 窗体”，在“名称”框中键入 WorkflowHostForm，然后单击“添加”。

  3. 在窗体上配置以下属性。

    属性 值
    FormBorderStyle FixedSingle
    MaximizeBox 错误
    大小 400, 420

  4. 按照指定顺序将以下控件添加到窗体，并根据指示配置这些属性。

    控制 属性：值
    Button 名称：NewGame

    位置：13、13

    大小：75、23

    文本：新游戏
    标签 位置：94、18

    文本：猜测一个数字，从 1 到
    ComboBox 名称：NumberRange

    DropDownStyle：DropDownList

    项：10、100、1000

    位置：228、12

    大小：143、21
    标签 位置：13、43

    文本：工作流类型
    ComboBox 名称：WorkflowType

    DropDownStyle：DropDownList

    项：StateMachineNumberGuessWorkflow、FlowchartNumberGuessWorkflow、SequentialNumberGuessWorkflow

    位置：94、40

    大小：277、21
    标签 名称：WorkflowVersion

    位置：13、362

    文本：工作流版本
    GroupBox 位置：13、67

    大小：358、287

    文本：游戏

    注意

    添加以下控件时，将其放入 GroupBox 中。

    控制 属性：值
    标签 位置：7、20

    文本：工作流实例 ID
    ComboBox 名称：InstanceId

    DropDownStyle：DropDownList

    位置：121、17

    大小：227、21
    标签 位置：7、47

    文本：推测
    TextBox 名称：Guess

    位置：50、44

    大小：65、20
    Button 名称：EnterGuess

    位置：121、42

    大小：75、23

    名称：输入推测
    Button 名称：QuitGame

    位置：274、42

    大小：75、23

    文本：退出
    TextBox 名称：WorkflowStatus

    位置：10、73

    多行：True

    只读：True

    滚动条：垂直

    大小：338、208

  5. 将窗体的“AcceptButton”属性设置为“EnterGuess”。

以下示例展示了完成的窗体。

屏幕截图显示 Windows Workflow Foundation 工作流主机窗体。

添加窗体的属性和帮助器方法

本节的步骤将属性和帮助器添加至窗体类，此窗体类将配置窗体的 UI，以支持运行和恢复数字猜测工作流。

  1. 在解决方案资源管理器中右键单击“WorkflowHostForm”，然后选择“查看代码”。

  2. 在包含其他 using（或 Imports）语句的文件的顶部添加以下 using（或 Imports）语句。

    Imports System.Activities
Imports System.Activities.DurableInstancing
Imports System.Data.SqlClient
Imports System.IO
Imports System.Windows.Forms

    using System.Activities;
using System.Activities.DurableInstancing;
using System.Data.SqlClient;
using System.IO;
using System.Windows.Forms;

  3. 将以下成员声明添加到“WorkflowHostForm”类中。

    重要

    Microsoft 建议使用最安全的可用身份验证流。 如果要连接到 Azure SQL，建议使用 Azure 资源的托管标识这种身份验证方法。

    Const connectionString = "Server=.\SQLEXPRESS;Initial Catalog=WF45GettingStartedTutorial;Integrated Security=SSPI"
Dim store As SqlWorkflowInstanceStore
Dim workflowStarting As Boolean

    const string connectionString = "Server=.\\SQLEXPRESS;Initial Catalog=WF45GettingStartedTutorial;Integrated Security=SSPI";
SqlWorkflowInstanceStore store;
bool workflowStarting;

    注意

    如果您的连接字符串不同，请更新 connectionString 引用数据库。

  4. 将 WorkflowInstanceId 属性添加到 WorkflowFormHost 类中。

    Public ReadOnly Property WorkflowInstanceId() As Guid
    Get
        If InstanceId.SelectedIndex = -1 Then
            Return Guid.Empty
        Else
            Return New Guid(InstanceId.SelectedItem.ToString())
        End If
    End Get
End Property

    public Guid WorkflowInstanceId
{
    get
    {
        return InstanceId.SelectedIndex == -1 ? Guid.Empty : (Guid)InstanceId.SelectedItem;
    }
}

    组合框显示持久性工作流实例 ID 的列表， 属性则返回当前选择的工作流InstanceIdWorkflowInstanceId。

  5. 为窗体 Load 事件添加处理程序。 要添加该处理程序，请切换到窗体的“设计视图”，单击“属性”窗口顶部的“事件”图标，然后双击“Load”。

    Private Sub WorkflowHostForm_Load(sender As Object, e As EventArgs) Handles Me.Load

End Sub

    private void WorkflowHostForm_Load(object sender, EventArgs e)
{

}

  6. 将以下代码添加到 WorkflowHostForm_Load。

    ' Initialize the store and configure it so that it can be used for
' multiple WorkflowApplication instances.
store = New SqlWorkflowInstanceStore(connectionString)
WorkflowApplication.CreateDefaultInstanceOwner(store, Nothing, WorkflowIdentityFilter.Any)

' Set default ComboBox selections.
NumberRange.SelectedIndex = 0
WorkflowType.SelectedIndex = 0

ListPersistedWorkflows()

    // Initialize the store and configure it so that it can be used for
// multiple WorkflowApplication instances.
store = new SqlWorkflowInstanceStore(connectionString);
WorkflowApplication.CreateDefaultInstanceOwner(store, null, WorkflowIdentityFilter.Any);

// Set default ComboBox selections.
NumberRange.SelectedIndex = 0;
WorkflowType.SelectedIndex = 0;

ListPersistedWorkflows();

    窗体加载时，将配置 SqlWorkflowInstanceStore，范围和工作流类型组合框将设置为默认值，持久性工作流实例将添加到 InstanceId 组合框。

  7. 为 SelectedIndexChanged 添加 InstanceId 处理程序。 要添加该处理程序，请切换到窗体的“设计视图”，选择 InstanceId 组合框，单击“属性”窗口顶部的“事件”图标，然后双击“SelectedIndexChanged”。

    Private Sub InstanceId_SelectedIndexChanged(sender As Object, e As EventArgs) Handles InstanceId.SelectedIndexChanged

End Sub

    private void InstanceId_SelectedIndexChanged(object sender, EventArgs e)
{

}

  8. 将以下代码添加到 InstanceId_SelectedIndexChanged。 只要用户使用组合框选择一个工作流，此处理程序就会更新状态窗口。

    If InstanceId.SelectedIndex = -1 Then
    Return
End If

' Clear the status window.
WorkflowStatus.Clear()

' Get the workflow version and display it.
' If the workflow is just starting then this info will not
' be available in the persistence store so do not try and retrieve it.
If Not workflowStarting Then
    Dim instance As WorkflowApplicationInstance = _
        WorkflowApplication.GetInstance(WorkflowInstanceId, store)

    WorkflowVersion.Text = _
        WorkflowVersionMap.GetIdentityDescription(instance.DefinitionIdentity)

    ' Unload the instance.
    instance.Abandon()
End If

    if (InstanceId.SelectedIndex == -1)
{
    return;
}

// Clear the status window.
WorkflowStatus.Clear();

// Get the workflow version and display it.
// If the workflow is just starting then this info will not
// be available in the persistence store so do not try and retrieve it.
if (!workflowStarting)
{
    WorkflowApplicationInstance instance =
        WorkflowApplication.GetInstance(this.WorkflowInstanceId, store);

    WorkflowVersion.Text =
        WorkflowVersionMap.GetIdentityDescription(instance.DefinitionIdentity);

    // Unload the instance.
    instance.Abandon();
}

  9. 将下面的 ListPersistedWorkflows 方法添加到窗体类中。

    Private Sub ListPersistedWorkflows()
    Using localCon As New SqlConnection(connectionString)
        Dim localCmd As String = _
            "SELECT [InstanceId] FROM [System.Activities.DurableInstancing].[Instances] ORDER BY [CreationTime]"

        Dim cmd As SqlCommand = localCon.CreateCommand()
        cmd.CommandText = localCmd
        localCon.Open()
        Using reader As SqlDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection)

            While (reader.Read())
                ' Get the InstanceId of the persisted Workflow.
                Dim id As Guid = Guid.Parse(reader(0).ToString())
                InstanceId.Items.Add(id)
            End While
        End Using
    End Using
End Sub

    using (var localCon = new SqlConnection(connectionString))
{
    string localCmd =
        "SELECT [InstanceId] FROM [System.Activities.DurableInstancing].[Instances] ORDER BY [CreationTime]";

    SqlCommand cmd = localCon.CreateCommand();
    cmd.CommandText = localCmd;
    localCon.Open();
    using (SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection))
    {
        while (reader.Read())
        {
            // Get the InstanceId of the persisted Workflow.
            Guid id = Guid.Parse(reader[0].ToString());
            InstanceId.Items.Add(id);
        }
    }
}

    ListPersistedWorkflows 查询持久性工作流实例的实例存储，并将实例 ID 添加到 cboInstanceId 组合框。

  10. 将下面的 UpdateStatus 方法和对应的委托添加到窗体类中。 此方法使用当前正在运行的工作流的状态来更新窗体上的状态窗口。

    Private Delegate Sub UpdateStatusDelegate(msg As String)
Public Sub UpdateStatus(msg As String)
    ' We may be on a different thread so we need to
    ' make this call using BeginInvoke.
    If InvokeRequired Then
        BeginInvoke(New UpdateStatusDelegate(AddressOf UpdateStatus), msg)
    Else
        If Not msg.EndsWith(vbCrLf) Then
            msg = msg & vbCrLf
        End If

        WorkflowStatus.AppendText(msg)

        ' Ensure that the newly added status is visible.
        WorkflowStatus.SelectionStart = WorkflowStatus.Text.Length
        WorkflowStatus.ScrollToCaret()
    End If
End Sub

    private delegate void UpdateStatusDelegate(string msg);
public void UpdateStatus(string msg)
{
    // We may be on a different thread so we need to
    // make this call using BeginInvoke.
    if (InvokeRequired)
    {
        BeginInvoke(new UpdateStatusDelegate(UpdateStatus), msg);
    }
    else
    {
        if (!msg.EndsWith("\r\n"))
        {
            msg += "\r\n";
        }
        WorkflowStatus.AppendText(msg);

        WorkflowStatus.SelectionStart = WorkflowStatus.Text.Length;
        WorkflowStatus.ScrollToCaret();
    }
}

  11. 将下面的 GameOver 方法和对应的委托添加到窗体类中。 工作流完成时，此方法会从“InstanceId”组合框中删除已完成工作流的实例 ID，从而更新窗体 UI。

    Private Delegate Sub GameOverDelegate()
Private Sub GameOver()
    If InvokeRequired Then
        BeginInvoke(New GameOverDelegate(AddressOf GameOver))
    Else
        ' Remove this instance from the InstanceId combo box.
        InstanceId.Items.Remove(InstanceId.SelectedItem)
        InstanceId.SelectedIndex = -1
    End If
End Sub

    private delegate void GameOverDelegate();
private void GameOver()
{
    if (InvokeRequired)
    {
        BeginInvoke(new GameOverDelegate(GameOver));
    }
    else
    {
        // Remove this instance from the combo box.
        InstanceId.Items.Remove(InstanceId.SelectedItem);
        InstanceId.SelectedIndex = -1;
    }
}

配置实例存储、工作流生命周期处理程序和扩展

  1. 向窗体类添加 ConfigureWorkflowApplication 方法。

    Private Sub ConfigureWorkflowApplication(wfApp As WorkflowApplication)

End Sub

    private void ConfigureWorkflowApplication(WorkflowApplication wfApp)
{
}

    此方法配置 WorkflowApplication、添加所需扩展并添加工作流生命周期事件的处理程序。

  2. 在 ConfigureWorkflowApplication 中，指定 SqlWorkflowInstanceStore 的 WorkflowApplication。

    ' Configure the persistence store.
wfApp.InstanceStore = store

    // Configure the persistence store.
wfApp.InstanceStore = store;

  3. 接下来，创建一个 StringWriter 实例，并将它添加到 Extensions 的 WorkflowApplication 集合中。 当 StringWriter 添加到扩展中时，它会捕获所有 WriteLine 活动输出。 当工作流进入空闲状态时，WriteLine 输出可从 StringWriter 提取并显示在窗体上。

    ' Add a StringWriter to the extensions. This captures the output
' from the WriteLine activities so we can display it in the form.
Dim sw As New StringWriter()
wfApp.Extensions.Add(sw)

    // Add a StringWriter to the extensions. This captures the output
// from the WriteLine activities so we can display it in the form.
var sw = new StringWriter();
wfApp.Extensions.Add(sw);

  4. 为 Completed 事件添加以下处理程序。 在工作流成功完成时，执行猜测数字的轮数会显示到状态窗口。 如果工作流终止，系统会显示导致终止的异常信息。 在处理程序结尾处调用了 GameOver 方法，该方法从工作流列表中删除已完成的工作流。

    wfApp.Completed = _
    Sub(e As WorkflowApplicationCompletedEventArgs)
        If e.CompletionState = ActivityInstanceState.Faulted Then
            UpdateStatus($"Workflow Terminated. Exception: {e.TerminationException.GetType().FullName}{vbCrLf}{e.TerminationException.Message}")
        ElseIf e.CompletionState = ActivityInstanceState.Canceled Then
            UpdateStatus("Workflow Canceled.")
        Else
            Dim turns As Integer = Convert.ToInt32(e.Outputs("Turns"))
            UpdateStatus($"Congratulations, you guessed the number in {turns} turns.")
        End If
        GameOver()
    End Sub

    wfApp.Completed = delegate(WorkflowApplicationCompletedEventArgs e)
{
    if (e.CompletionState == ActivityInstanceState.Faulted)
    {
        UpdateStatus($"Workflow Terminated. Exception: {e.TerminationException.GetType().FullName}\r\n{e.TerminationException.Message}");
    }
    else if (e.CompletionState == ActivityInstanceState.Canceled)
    {
        UpdateStatus("Workflow Canceled.");
    }
    else
    {
        int turns = Convert.ToInt32(e.Outputs["Turns"]);
        UpdateStatus($"Congratulations, you guessed the number in {turns} turns.");
    }
    GameOver();
};

  5. 添加以下 Aborted 和 OnUnhandledException 处理程序。 GameOver 方法不从 Aborted 处理程序中调用，因为在工作流实例中止时，它并未终止，且以后可能恢复实例。

    wfApp.Aborted = _
    Sub(e As WorkflowApplicationAbortedEventArgs)
        UpdateStatus($"Workflow Aborted. Exception: {e.Reason.GetType().FullName}{vbCrLf}{e.Reason.Message}")
    End Sub

wfApp.OnUnhandledException = _
    Function(e As WorkflowApplicationUnhandledExceptionEventArgs)
        UpdateStatus($"Unhandled Exception: {e.UnhandledException.GetType().FullName}{vbCrLf}{e.UnhandledException.Message}")
        GameOver()
        Return UnhandledExceptionAction.Terminate
    End Function

    wfApp.Aborted = delegate(WorkflowApplicationAbortedEventArgs e)
{
    UpdateStatus($"Workflow Aborted. Exception: {e.Reason.GetType().FullName}\r\n{e.Reason.Message}");
};

wfApp.OnUnhandledException = delegate(WorkflowApplicationUnhandledExceptionEventArgs e)
{
    UpdateStatus($"Unhandled Exception: {e.UnhandledException.GetType().FullName}\r\n{e.UnhandledException.Message}");
    GameOver();
    return UnhandledExceptionAction.Terminate;
};

  6. 添加以下 PersistableIdle 处理程序。 此处理程序检索添加的 StringWriter 扩展，提取 WriteLine 活动的输出，并将它显示在状态窗口中。

    wfApp.PersistableIdle = _
    Function(e As WorkflowApplicationIdleEventArgs)
        ' Send the current WriteLine outputs to the status window.
        Dim writers = e.GetInstanceExtensions(Of StringWriter)()
        For Each writer In writers
            UpdateStatus(writer.ToString())
        Next
        Return PersistableIdleAction.Unload
    End Function

    wfApp.PersistableIdle = delegate(WorkflowApplicationIdleEventArgs e)
{
    // Send the current WriteLine outputs to the status window.
    var writers = e.GetInstanceExtensions<StringWriter>();
    foreach (var writer in writers)
    {
        UpdateStatus(writer.ToString());
    }
    return PersistableIdleAction.Unload;
};

    PersistableIdleAction 枚举有三个值：None、 Persist 和 Unload。 Persist 会导致工作流持久保存，但不会导致工作流卸载。 Unload 会导致工作流持久保存并卸载。

    以下示例是完成的 ConfigureWorkflowApplication 方法。

    Private Sub ConfigureWorkflowApplication(wfApp As WorkflowApplication)
    ' Configure the persistence store.
    wfApp.InstanceStore = store

    ' Add a StringWriter to the extensions. This captures the output
    ' from the WriteLine activities so we can display it in the form.
    Dim sw As New StringWriter()
    wfApp.Extensions.Add(sw)

    wfApp.Completed = _
        Sub(e As WorkflowApplicationCompletedEventArgs)
            If e.CompletionState = ActivityInstanceState.Faulted Then
                UpdateStatus($"Workflow Terminated. Exception: {e.TerminationException.GetType().FullName}{vbCrLf}{e.TerminationException.Message}")
            ElseIf e.CompletionState = ActivityInstanceState.Canceled Then
                UpdateStatus("Workflow Canceled.")
            Else
                Dim turns As Integer = Convert.ToInt32(e.Outputs("Turns"))
                UpdateStatus($"Congratulations, you guessed the number in {turns} turns.")
            End If
            GameOver()
        End Sub

    wfApp.Aborted = _
        Sub(e As WorkflowApplicationAbortedEventArgs)
            UpdateStatus($"Workflow Aborted. Exception: {e.Reason.GetType().FullName}{vbCrLf}{e.Reason.Message}")
        End Sub

    wfApp.OnUnhandledException = _
        Function(e As WorkflowApplicationUnhandledExceptionEventArgs)
            UpdateStatus($"Unhandled Exception: {e.UnhandledException.GetType().FullName}{vbCrLf}{e.UnhandledException.Message}")
            GameOver()
            Return UnhandledExceptionAction.Terminate
        End Function

    wfApp.PersistableIdle = _
        Function(e As WorkflowApplicationIdleEventArgs)
            ' Send the current WriteLine outputs to the status window.
            Dim writers = e.GetInstanceExtensions(Of StringWriter)()
            For Each writer In writers
                UpdateStatus(writer.ToString())
            Next
            Return PersistableIdleAction.Unload
        End Function
End Sub

    private void ConfigureWorkflowApplication(WorkflowApplication wfApp)
{
    // Configure the persistence store.
    wfApp.InstanceStore = store;

    // Add a StringWriter to the extensions. This captures the output
    // from the WriteLine activities so we can display it in the form.
    var sw = new StringWriter();
    wfApp.Extensions.Add(sw);

    wfApp.Completed = delegate(WorkflowApplicationCompletedEventArgs e)
    {
        if (e.CompletionState == ActivityInstanceState.Faulted)
        {
            UpdateStatus($"Workflow Terminated. Exception: {e.TerminationException.GetType().FullName}\r\n{e.TerminationException.Message}");
        }
        else if (e.CompletionState == ActivityInstanceState.Canceled)
        {
            UpdateStatus("Workflow Canceled.");
        }
        else
        {
            int turns = Convert.ToInt32(e.Outputs["Turns"]);
            UpdateStatus($"Congratulations, you guessed the number in {turns} turns.");
        }
        GameOver();
    };

    wfApp.Aborted = delegate(WorkflowApplicationAbortedEventArgs e)
    {
        UpdateStatus($"Workflow Aborted. Exception: {e.Reason.GetType().FullName}\r\n{e.Reason.Message}");
    };

    wfApp.OnUnhandledException = delegate(WorkflowApplicationUnhandledExceptionEventArgs e)
    {
        UpdateStatus($"Unhandled Exception: {e.UnhandledException.GetType().FullName}\r\n{e.UnhandledException.Message}");
        GameOver();
        return UnhandledExceptionAction.Terminate;
    };

    wfApp.PersistableIdle = delegate(WorkflowApplicationIdleEventArgs e)
    {
        // Send the current WriteLine outputs to the status window.
        var writers = e.GetInstanceExtensions<StringWriter>();
        foreach (var writer in writers)
        {
            UpdateStatus(writer.ToString());
        }
        return PersistableIdleAction.Unload;
    };
}

支持启动和恢复多个工作流类型

要恢复工作流实例，主机必须提供工作流定义。 在此教程中有三个工作流类型，且后续教程步骤会介绍这些类型的多个版本。 主机应用程序可通过 WorkflowIdentity 将标识信息与持久化工作流实例相关联。 本节中的步骤演示了如何创建一个实用工具类，以帮助将工作流标识从持久化工作流实例映射到对应的工作流定义。 有关 WorkflowIdentity 和版本控制的详细信息，请参阅使用 WorkflowIdentity 和版本控制。

  1. 在解决方案资源管理器中右键单击“NumberGuessWorkflowHost”，然后选择“添加”和“类”。 在“名称”框中键入 WorkflowVersionMap，然后单击“确定”。

  2. 在包含其他 using 或 Imports 语句的文件的顶部添加以下 using 或 Imports 语句。

    Imports System.Activities
Imports NumberGuessWorkflowActivities

    using System.Activities;
using NumberGuessWorkflowActivities;

  3. 使用以下声明替换 WorkflowVersionMap 类声明。

    Public Module WorkflowVersionMap
    Dim map As Dictionary(Of WorkflowIdentity, Activity)

    ' Current version identities.
    Public StateMachineNumberGuessIdentity As WorkflowIdentity
    Public FlowchartNumberGuessIdentity As WorkflowIdentity
    Public SequentialNumberGuessIdentity As WorkflowIdentity

    Sub New()
        map = New Dictionary(Of WorkflowIdentity, Activity)

        ' Add the current workflow version identities.
        StateMachineNumberGuessIdentity = New WorkflowIdentity With
        {
            .Name = "StateMachineNumberGuessWorkflow",
            .Version = New Version(1, 0, 0, 0)
        }

        FlowchartNumberGuessIdentity = New WorkflowIdentity With
        {
            .Name = "FlowchartNumberGuessWorkflow",
            .Version = New Version(1, 0, 0, 0)
        }

        SequentialNumberGuessIdentity = New WorkflowIdentity With
        {
            .Name = "SequentialNumberGuessWorkflow",
            .Version = New Version(1, 0, 0, 0)
        }

        map.Add(StateMachineNumberGuessIdentity, New StateMachineNumberGuessWorkflow())
        map.Add(FlowchartNumberGuessIdentity, New FlowchartNumberGuessWorkflow())
        map.Add(SequentialNumberGuessIdentity, New SequentialNumberGuessWorkflow())
    End Sub

    Public Function GetWorkflowDefinition(identity As WorkflowIdentity) As Activity
        Return map(identity)
    End Function

    Public Function GetIdentityDescription(identity As WorkflowIdentity) As String
        Return identity.ToString()
    End Function
End Module

    public static class WorkflowVersionMap
{
    static Dictionary<WorkflowIdentity, Activity> map;

    // Current version identities.
    static public WorkflowIdentity StateMachineNumberGuessIdentity;
    static public WorkflowIdentity FlowchartNumberGuessIdentity;
    static public WorkflowIdentity SequentialNumberGuessIdentity;

    static WorkflowVersionMap()
    {
        map = new Dictionary<WorkflowIdentity, Activity>();

        // Add the current workflow version identities.
        StateMachineNumberGuessIdentity = new WorkflowIdentity
        {
            Name = "StateMachineNumberGuessWorkflow",
            Version = new Version(1, 0, 0, 0)
        };

        FlowchartNumberGuessIdentity = new WorkflowIdentity
        {
            Name = "FlowchartNumberGuessWorkflow",
            Version = new Version(1, 0, 0, 0)
        };

        SequentialNumberGuessIdentity = new WorkflowIdentity
        {
            Name = "SequentialNumberGuessWorkflow",
            Version = new Version(1, 0, 0, 0)
        };

        map.Add(StateMachineNumberGuessIdentity, new StateMachineNumberGuessWorkflow());
        map.Add(FlowchartNumberGuessIdentity, new FlowchartNumberGuessWorkflow());
        map.Add(SequentialNumberGuessIdentity, new SequentialNumberGuessWorkflow());
    }

    public static Activity GetWorkflowDefinition(WorkflowIdentity identity)
    {
        return map[identity];
    }

    public static string GetIdentityDescription(WorkflowIdentity identity)
    {
        return identity.ToString();
   }
}

    WorkflowVersionMap 包含与此教程中的三个工作流定义对应的三个工作流标识，并在以下各节中工作流启动和恢复时使用。

启动新工作流

  1. 为 Click 添加 NewGame 处理程序。 要添加该处理程序，请切换到窗体的“设计视图”，然后双击 NewGame。 此时将添加 NewGame_Click 处理程序，视图将切换为窗体的代码视图。 每当用户单击此按钮时，就会启动新工作流。

    Private Sub NewGame_Click(sender As Object, e As EventArgs) Handles NewGame.Click

End Sub

    private void NewGame_Click(object sender, EventArgs e)
{

}

  2. 将以下代码添加到 click 处理程序。 此代码创建工作流输入自变量的字典，以变量名称作为键。 此字典有一个条目，其中包含从范围组合框检索到的随机生成的数字范围。

    Dim inputs As New Dictionary(Of String, Object)()
inputs.Add("MaxNumber", Convert.ToInt32(NumberRange.SelectedItem))

    var inputs = new Dictionary<string, object>();
inputs.Add("MaxNumber", Convert.ToInt32(NumberRange.SelectedItem));

  3. 接下来，添加以下用于启动工作流的代码。 对应于所选工作流类型的 WorkflowIdentity 和工作流定义通过 WorkflowVersionMap 帮助器类进行检索。 接下来，将使用工作流定义、WorkflowApplication 和输入变量字典创建新的 WorkflowIdentity 实例。

    Dim identity As WorkflowIdentity = Nothing
Select Case WorkflowType.SelectedItem.ToString()
    Case "SequentialNumberGuessWorkflow"
        identity = WorkflowVersionMap.SequentialNumberGuessIdentity

    Case "StateMachineNumberGuessWorkflow"
        identity = WorkflowVersionMap.StateMachineNumberGuessIdentity

    Case "FlowchartNumberGuessWorkflow"
        identity = WorkflowVersionMap.FlowchartNumberGuessIdentity
End Select

Dim wf As Activity = WorkflowVersionMap.GetWorkflowDefinition(identity)

Dim wfApp = New WorkflowApplication(wf, inputs, identity)

    WorkflowIdentity identity = null;
switch (WorkflowType.SelectedItem.ToString())
{
    case "SequentialNumberGuessWorkflow":
        identity = WorkflowVersionMap.SequentialNumberGuessIdentity;
        break;

    case "StateMachineNumberGuessWorkflow":
        identity = WorkflowVersionMap.StateMachineNumberGuessIdentity;
        break;

    case "FlowchartNumberGuessWorkflow":
        identity = WorkflowVersionMap.FlowchartNumberGuessIdentity;
        break;
};

Activity wf = WorkflowVersionMap.GetWorkflowDefinition(identity);

WorkflowApplication wfApp = new WorkflowApplication(wf, inputs, identity);

  4. 接下来，添加以下代码，此代码将工作流添加到工作流列表中，并在窗体上显示工作流的版本信息。

    ' Add the workflow to the list and display the version information.
workflowStarting = True
InstanceId.SelectedIndex = InstanceId.Items.Add(wfApp.Id)
WorkflowVersion.Text = identity.ToString()
workflowStarting = False

    // Add the workflow to the list and display the version information.
workflowStarting = true;
InstanceId.SelectedIndex = InstanceId.Items.Add(wfApp.Id);
WorkflowVersion.Text = identity.ToString();
workflowStarting = false;

  5. 调用 ConfigureWorkflowApplication 为此 WorkflowApplication 实例配置实例存储、扩展以及工作流生命周期处理程序。

    ' Configure the instance store, extensions, and
' workflow lifecycle handlers.
ConfigureWorkflowApplication(wfApp)

    // Configure the instance store, extensions, and
// workflow lifecycle handlers.
ConfigureWorkflowApplication(wfApp);

  6. 最后，调用 Run。

    ' Start the workflow.
wfApp.Run()

    // Start the workflow.
wfApp.Run();

    以下示例是完成的 NewGame_Click 处理程序。

    Private Sub NewGame_Click(sender As Object, e As EventArgs) Handles NewGame.Click
    ' Start a new workflow.
    Dim inputs As New Dictionary(Of String, Object)()
    inputs.Add("MaxNumber", Convert.ToInt32(NumberRange.SelectedItem))

    Dim identity As WorkflowIdentity = Nothing
    Select Case WorkflowType.SelectedItem.ToString()
        Case "SequentialNumberGuessWorkflow"
            identity = WorkflowVersionMap.SequentialNumberGuessIdentity

        Case "StateMachineNumberGuessWorkflow"
            identity = WorkflowVersionMap.StateMachineNumberGuessIdentity

        Case "FlowchartNumberGuessWorkflow"
            identity = WorkflowVersionMap.FlowchartNumberGuessIdentity
    End Select

    Dim wf As Activity = WorkflowVersionMap.GetWorkflowDefinition(identity)

    Dim wfApp = New WorkflowApplication(wf, inputs, identity)

    ' Add the workflow to the list and display the version information.
    workflowStarting = True
    InstanceId.SelectedIndex = InstanceId.Items.Add(wfApp.Id)
    WorkflowVersion.Text = identity.ToString()
    workflowStarting = False

    ' Configure the instance store, extensions, and
    ' workflow lifecycle handlers.
    ConfigureWorkflowApplication(wfApp)

    ' Start the workflow.
    wfApp.Run()
End Sub

    private void NewGame_Click(object sender, EventArgs e)
{
    var inputs = new Dictionary<string, object>();
    inputs.Add("MaxNumber", Convert.ToInt32(NumberRange.SelectedItem));

    WorkflowIdentity identity = null;
    switch (WorkflowType.SelectedItem.ToString())
    {
        case "SequentialNumberGuessWorkflow":
            identity = WorkflowVersionMap.SequentialNumberGuessIdentity;
            break;

        case "StateMachineNumberGuessWorkflow":
            identity = WorkflowVersionMap.StateMachineNumberGuessIdentity;
            break;

        case "FlowchartNumberGuessWorkflow":
            identity = WorkflowVersionMap.FlowchartNumberGuessIdentity;
            break;
    };

    Activity wf = WorkflowVersionMap.GetWorkflowDefinition(identity);

    var wfApp = new WorkflowApplication(wf, inputs, identity);

    // Add the workflow to the list and display the version information.
    workflowStarting = true;
    InstanceId.SelectedIndex = InstanceId.Items.Add(wfApp.Id);
    WorkflowVersion.Text = identity.ToString();
    workflowStarting = false;

    // Configure the instance store, extensions, and
    // workflow lifecycle handlers.
    ConfigureWorkflowApplication(wfApp);

    // Start the workflow.
    wfApp.Run();
}

恢复工作流

  1. 为 Click 添加 EnterGuess 处理程序。 要添加该处理程序，请切换到窗体的“设计视图”，然后双击 EnterGuess。 每当用户单击此按钮时，就会恢复工作流。

    Private Sub EnterGuess_Click(sender As Object, e As EventArgs) Handles EnterGuess.Click

End Sub

    private void EnterGuess_Click(object sender, EventArgs e)
{

}

  2. 添加以下代码，以确保在工作流列表中选择了一个工作流，且用户的猜测有效。

    If WorkflowInstanceId = Guid.Empty Then
    MessageBox.Show("Please select a workflow.")
    Return
End If

Dim userGuess As Integer
If Not Int32.TryParse(Guess.Text, userGuess) Then
    MessageBox.Show("Please enter an integer.")
    Guess.SelectAll()
    Guess.Focus()
    Return
End If

    if (WorkflowInstanceId == Guid.Empty)
{
    MessageBox.Show("Please select a workflow.");
    return;
}

int guess;
if (!Int32.TryParse(Guess.Text, out guess))
{
    MessageBox.Show("Please enter an integer.");
    Guess.SelectAll();
    Guess.Focus();
    return;
}

  3. 接下来，检索持久化工作流实例的 WorkflowApplicationInstance。 WorkflowApplicationInstance 表示尚未与工作流定义关联的持久化工作流实例。 DefinitionIdentity 的 WorkflowApplicationInstance 包含持久化工作流实例的 WorkflowIdentity。 本教程中使用 WorkflowVersionMap 实用工具类，将 WorkflowIdentity 映射到正确的工作流定义。 检索工作流定义后，即使用正确的工作流定义创建 WorkflowApplication。

    Dim instance As WorkflowApplicationInstance = _
    WorkflowApplication.GetInstance(WorkflowInstanceId, store)

' Use the persisted WorkflowIdentity to retrieve the correct workflow
' definition from the dictionary.
Dim wf As Activity = _
    WorkflowVersionMap.GetWorkflowDefinition(instance.DefinitionIdentity)

' Associate the WorkflowApplication with the correct definition
Dim wfApp As New WorkflowApplication(wf, instance.DefinitionIdentity)

    WorkflowApplicationInstance instance =
    WorkflowApplication.GetInstance(WorkflowInstanceId, store);

// Use the persisted WorkflowIdentity to retrieve the correct workflow
// definition from the dictionary.
Activity wf =
    WorkflowVersionMap.GetWorkflowDefinition(instance.DefinitionIdentity);

// Associate the WorkflowApplication with the correct definition
var wfApp = new WorkflowApplication(wf, instance.DefinitionIdentity);

  4. 创建 WorkflowApplication 后，请调用 ConfigureWorkflowApplication 以配置实例存储、工作流生命周期处理程序以及扩展。 每次创建新 WorkflowApplication 时都必须执行这些步骤，并且必须在将工作流实例加载到 WorkflowApplication 中之前完成。 在加载工作流后，此工作流通过用户的猜测恢复执行。

    ' Configure the extensions and lifecycle handlers.
' Do this before the instance is loaded. Once the instance is
' loaded it is too late to add extensions.
ConfigureWorkflowApplication(wfApp)

' Load the workflow.
wfApp.Load(instance)

' Resume the workflow.
wfApp.ResumeBookmark("EnterGuess", userGuess)

    // Configure the extensions and lifecycle handlers.
// Do this before the instance is loaded. Once the instance is
// loaded it is too late to add extensions.
ConfigureWorkflowApplication(wfApp);

// Load the workflow.
wfApp.Load(instance);

// Resume the workflow.
wfApp.ResumeBookmark("EnterGuess", guess);

  5. 最后，清除猜测文本框，并使窗体准备接受其他猜测。

    ' Clear the Guess textbox.
Guess.Clear()
Guess.Focus()

    // Clear the Guess textbox.
Guess.Clear();
Guess.Focus();

    以下示例是完成的 EnterGuess_Click 处理程序。

    Private Sub EnterGuess_Click(sender As Object, e As EventArgs) Handles EnterGuess.Click
    If WorkflowInstanceId = Guid.Empty Then
        MessageBox.Show("Please select a workflow.")
        Return
    End If

    Dim userGuess As Integer
    If Not Int32.TryParse(Guess.Text, userGuess) Then
        MessageBox.Show("Please enter an integer.")
        Guess.SelectAll()
        Guess.Focus()
        Return
    End If

    Dim instance As WorkflowApplicationInstance = _
        WorkflowApplication.GetInstance(WorkflowInstanceId, store)

    ' Use the persisted WorkflowIdentity to retrieve the correct workflow
    ' definition from the dictionary.
    Dim wf As Activity = _
        WorkflowVersionMap.GetWorkflowDefinition(instance.DefinitionIdentity)

    ' Associate the WorkflowApplication with the correct definition
    Dim wfApp As New WorkflowApplication(wf, instance.DefinitionIdentity)

    ' Configure the extensions and lifecycle handlers.
    ' Do this before the instance is loaded. Once the instance is
    ' loaded it is too late to add extensions.
    ConfigureWorkflowApplication(wfApp)

    ' Load the workflow.
    wfApp.Load(instance)

    ' Resume the workflow.
    wfApp.ResumeBookmark("EnterGuess", userGuess)

    ' Clear the Guess textbox.
    Guess.Clear()
    Guess.Focus()
End Sub

    private void EnterGuess_Click(object sender, EventArgs e)
{
    if (WorkflowInstanceId == Guid.Empty)
    {
        MessageBox.Show("Please select a workflow.");
        return;
    }

    int guess;
    if (!Int32.TryParse(Guess.Text, out guess))
    {
        MessageBox.Show("Please enter an integer.");
        Guess.SelectAll();
        Guess.Focus();
        return;
    }

    WorkflowApplicationInstance instance =
        WorkflowApplication.GetInstance(WorkflowInstanceId, store);

    // Use the persisted WorkflowIdentity to retrieve the correct workflow
    // definition from the dictionary.
    Activity wf =
        WorkflowVersionMap.GetWorkflowDefinition(instance.DefinitionIdentity);

    // Associate the WorkflowApplication with the correct definition
    var wfApp = new WorkflowApplication(wf, instance.DefinitionIdentity);

    // Configure the extensions and lifecycle handlers.
    // Do this before the instance is loaded. Once the instance is
    // loaded it is too late to add extensions.
    ConfigureWorkflowApplication(wfApp);

    // Load the workflow.
    wfApp.Load(instance);

    // Resume the workflow.
    wfApp.ResumeBookmark("EnterGuess", guess);

    // Clear the Guess textbox.
    Guess.Clear();
    Guess.Focus();
}

终止工作流

  1. 为 Click 添加 QuitGame 处理程序。 要添加该处理程序，请切换到窗体的“设计视图”，然后双击 QuitGame。 每当用户单击此按钮，即终止当前选择的工作流。

    Private Sub QuitGame_Click(sender As Object, e As EventArgs) Handles QuitGame.Click

End Sub

    private void QuitGame_Click(object sender, EventArgs e)
{

}

  2. 将以下代码添加到 QuitGame_Click 处理程序。 此代码首先进行检查，以确保在工作流列表中选择了一个工作流。 然后，它将该持久化实例加载到 WorkflowApplicationInstance 中，使用 DefinitionIdentity 确定正确的工作流定义，然后初始化 WorkflowApplication。 接下来，通过调用 ConfigureWorkflowApplication 来配置扩展和工作流生命周期处理程序。 WorkflowApplication 配置好后，将加载它，然后调用 Terminate。

    If WorkflowInstanceId = Guid.Empty Then
    MessageBox.Show("Please select a workflow.")
    Return
End If

Dim instance As WorkflowApplicationInstance = _
    WorkflowApplication.GetInstance(WorkflowInstanceId, store)

' Use the persisted WorkflowIdentity to retrieve the correct workflow
' definition from the dictionary.
Dim wf As Activity = WorkflowVersionMap.GetWorkflowDefinition(instance.DefinitionIdentity)

' Associate the WorkflowApplication with the correct definition.
Dim wfApp As New WorkflowApplication(wf, instance.DefinitionIdentity)

' Configure the extensions and lifecycle handlers.
ConfigureWorkflowApplication(wfApp)

' Load the workflow.
wfApp.Load(instance)

' Terminate the workflow.
wfApp.Terminate("User resigns.")

    if (WorkflowInstanceId == Guid.Empty)
{
    MessageBox.Show("Please select a workflow.");
    return;
}

WorkflowApplicationInstance instance =
    WorkflowApplication.GetInstance(WorkflowInstanceId, store);

// Use the persisted WorkflowIdentity to retrieve the correct workflow
// definition from the dictionary.
Activity wf = WorkflowVersionMap.GetWorkflowDefinition(instance.DefinitionIdentity);

// Associate the WorkflowApplication with the correct definition
var wfApp = new WorkflowApplication(wf, instance.DefinitionIdentity);

// Configure the extensions and lifecycle handlers
ConfigureWorkflowApplication(wfApp);

// Load the workflow.
wfApp.Load(instance);

// Terminate the workflow.
wfApp.Terminate("User resigns.");

生成并运行应用程序

  1. 在“解决方案资源管理器”中双击“Program.cs”或“Module1.vb”，以显示其代码。

  2. 在包含其他 using（或 Imports）语句的文件的顶部添加以下 using（或 Imports）语句。

    Imports System.Windows.Forms

    using System.Windows.Forms;

  3. 删除或注释掉如何：运行工作流中现有的工作流承载代码，并替换为以下代码。

    Sub Main()
    Application.EnableVisualStyles()
    Application.Run(New WorkflowHostForm())
End Sub

    static void Main(string[] args)
{
    Application.EnableVisualStyles();
    Application.Run(new WorkflowHostForm());
}

  4. 在解决方案资源管理器中右键单击“NumberGuessWorkflowHost”，然后选择“属性”。 在“应用程序”选项卡中，为“输出类型”指定“Windows 应用程序”。 此步骤是可选的，但如果不执行此步骤，则除了窗体之外还会显示控制台窗口。

  5. 按 Ctrl+Shift+B 生成应用程序。

  6. 确保将“NumberGuessWorkflowHost”设置为启动应用程序，并按 Ctrl+F5 启动应用程序。

  7. 为猜数游戏选择一个范围，并选择要启动的工作流类型，然后单击“新游戏”。 在“推测”框中输入猜测值，然后单击“继续”提交该值。 请注意，WriteLine 活动的输出将显示在窗体上。

  8. 使用不同的工作流类型和数字范围启动多个工作流，输入一些猜测值，然后从“工作流实例 ID”列表中进行选择以便在工作流之间进行切换。

    请注意，当切换到新工作流时，状态窗口中不会显示以前的猜测值和工作流进度。 状态不可用的原因是未将它捕获并保存在任何位置。 在教程的下一步，即如何：创建自定义跟踪参与者中，将创建保存此信息的自定义跟踪参与者。