使用WCF回调更新asp.net网格视图数据

Question

我有一个wsdualhttpbinding在asp.net Web应用程序中实现的WCF回调，我想用它来更新页面的gridview中的行。 我将gridview放在更新面板中，并且回调在客户端上启动，但是网格中的数据从未更新过。 我试图在调用databind无效后调用更新面板的Update（）方法。 有什么我想念的东西还是我需要做的才能使它起作用？

这是我正在使用的一些代码：

在页面加载中，我将附加到WCF回调，继承该回调的接口，并在该接口的实现中，使用从回调收到的数据绑定到网格：

[CallbackBehavior(ConcurrencyMode = ConcurrencyMode.Reentrant)]
public partial class activeJobs : System.Web.UI.UserControl, IAgentMessagingCallback
{
    AgentMessagingClient _messagingClient;

    protected void Page_Load(object sender, EventArgs e)
    {
        InstanceContext context = new InstanceContext(this);
        _messagingClient = new AgentMessagingClient(context, "AgentMessaging_IAgentMessaging");

        if (_messagingClient.Subscribe())
        {
            Page.Title = string.Format("Timeout will occur at {0}", DateTime.Now.AddMinutes(10));
        }
    }

    #region IAgentMessagingCallback Members

    public void ActiveJobs(SubmittedJob[] activeJobs1)
    {
        activeJobsGrid.DataSource = activeJobs1.ToList();
        //checked in the debugger, the data is actually recieved...
        activeJobsGrid.DataBind();

        //the update method for the updatepanel...tried this both ways, no go
        //activeJobsGridUP.Update(); 
    }

    #endregion
}

回调的定义如下：

[ServiceContract(CallbackContract = typeof(IAgentMessagingCallback))]
public interface IAgentMessaging
{
    [OperationContract(IsOneWay = true)]
    void SendActiveJobs(List<SubmittedJob> activeJobs);

    [OperationContract(IsOneWay = false)]
    bool Subscribe();

    [OperationContract(IsOneWay = false)]
    bool Unsubscribe();
}

public interface IAgentMessagingCallback
{
    [OperationContract(IsOneWay = true)]
    void ActiveJobs(List<SubmittedJob> activeJobs);
}

public class AgentMessaging : IAgentMessaging
{
    private static readonly List<IAgentMessagingCallback> _subscribers = new List<IAgentMessagingCallback>();

    #region IAgentMessaging Members

    public void SendActiveJobs(List<SubmittedJob> activeJobs)
    {
        _subscribers.ForEach(delegate(IAgentMessagingCallback callback)
        {
            if (((ICommunicationObject)callback).State == CommunicationState.Opened)
            {
                try
                {
                    callback.ActiveJobs(activeJobs);
                }
                catch (Exception ex)
                {
                    Messaging.ErrorMessage(ex, this.ToString());
                }
            }
            else
            {
                _subscribers.Remove(callback);
            }
        });
    }

    public bool Subscribe()
    {
        try
        {
            IAgentMessagingCallback callback = OperationContext.Current.GetCallbackChannel<IAgentMessagingCallback>();
            if (!_subscribers.Contains(callback))
            {
                _subscribers.Add(callback);
                return true;
            }
            else
            {
                return false;
            }
        }
        catch (Exception ex)
        {
            Messaging.ErrorMessage(ex, this.ToString());
            return false;
        }
    }

    public bool Unsubscribe()
    {
        try
        {
            IAgentMessagingCallback callback = OperationContext.Current.GetCallbackChannel<IAgentMessagingCallback>();
            if (_subscribers.Contains(callback))
            {
                _subscribers.Remove(callback);
                return true;
            }
            else
            {
                return false;
            }
        }
        catch (Exception ex)
        {
            Messaging.ErrorMessage(ex, this.ToString());
            return false;
        }
    }

    #endregion
}

Answer 1

回调是在您从Subscribe操作返回之前还是在Page_Load之后发生的？ 如果它发生在Page_Load之后，则我担心回调发生时页面是否仍然存在。

您是否意识到在每个请求上都会创建一个新的页面实例？ 而且，一旦HTML发送到客户端，实例就被丢弃了吗？ 将HTML发送到客户端后，服务器将无法对其进行更改。