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我的工作流书签选取触发器有什么问题?

workflow-activity workflow-foundation-4 .net-4.0 workflow c#

Jeff LaFay · 技术社区 · 14 年前

我有一个 NativeActivity 我编写的派生活动,它使用书签作为pick分支的触发器。我用在MSDN上找到的东西写了这个来触发分支。分支包含消防服务通过发送活动回调到远程客户端的活动。如果我为触发器设置了延迟,回调就会成功地触发到客户机。如果我使用代码活动,pick分支活动不会启动。

public sealed class UpdateListener : NativeActivity<ClientUpdate>
{
    [RequiredArgument]
    public InArgument<string>     BookmarkName { get; set; }

    protected override void Execute(NativeActivityContext context)
    {
        context.CreateBookmark(BookmarkName.Get(context),
                    new BookmarkCallback(this.OnResumeBookmark));
    }


    protected override bool CanInduceIdle
    {
        get { return true; }
    }


    public void OnResumeBookmark(NativeActivityContext context, Bookmark bookmark, object obj )
    {
        Result.Set(context, (ClientUpdate)obj);
    }
}

ClientUpdate 客户端更新

出于某种原因,这似乎是正确的,但感觉是错误的。我不确定是否应该以不同的方式编写活动,以满足WF服务的需要。

2 回复 | 直到 14 年前

user1228 user1228 14 年前

我认为如果您创建了一个扩展(实现IWorkflowInstanceExtension)来执行您的操作,您的意图会更清楚一些。

例如:

public sealed class AsyncWorkExtension 
    : IWorkflowInstanceExtension
{
    // only one extension per workflow
    private WorkflowInstanceProxy _proxy;
    private Bookmark _lastBookmark;

    /// <summary>
    /// Request the extension does some work for an activity
    /// during which the activity will idle the workflow
    /// </summary>
    /// <param name="toResumeMe"></param>
    public void DoWork(Bookmark toResumeMe)
    {
        _lastBookmark = toResumeMe;
        // imagine I kick off some async op here
        // when complete system calls WorkCompleted below
        // NOTE:  you CANNOT block here or you block the WF!
    }

    /// <summary>
    /// Called by the system when long-running work is complete
    /// </summary>
    /// <param name="result"></param>
    internal void WorkCompleted(object result)
    {
        //NOT good practice!  example only
        //this leaks resources search APM for details
        _proxy.BeginResumeBookmark(_lastBookmark, result, null, null);
    }

    /// <summary>
    /// When implemented, returns any additional extensions 
    /// the implementing class requires.
    /// </summary>
    /// <returns>
    /// A collection of additional workflow extensions.
    /// </returns>
    IEnumerable<object> IWorkflowInstanceExtension
        .GetAdditionalExtensions()
    {
        return new object[0];
    }

    /// <summary>
    /// Sets the specified target 
    /// <see cref="WorkflowInstanceProxy"/>.
    /// </summary>
    /// <param name="instance">The target workflow instance to set.</param>
    void IWorkflowInstanceExtension
        .SetInstance(WorkflowInstanceProxy instance)
    {
        _proxy = instance;
    }
}

 var ext = context.GetExtension<AsyncWorkExtension>();
 var bookmark = context.CreateBookmark(BookmarkCallback);
 ext.DoWork(bookmark);
 return;

这种方式更加明确(而不是使用书签名来向“外部”世界传达含义),并且如果您需要发送比书签名更多的信息,那么这种方式更容易扩展。

Maurice 14 年前