Ajax timer not polling when another request is being served_问答_开发者

Ajax timer not polling when another request is being served

开发者 https://www.devze.com 2023-03-24 00:35 出处：网络

In my form there there is a \"Submit Button\" and another Timer... Submit button submits a request that may take few minutes to serve..Mean while the timer would poll at short intervals (say 5 secs )

In my form there there is a "Submit Button" and another Timer... Submit button submits a request that may take few minutes to serve..Mean while the timer would poll at short intervals (say 5 secs ) and keep the user updated.. But the issue is that timer stops polling as soon as the Submit button is clicked.. I am attaching the working sample code of the application..Does anyone know why this is happening..Thanks in advance.

<body>
    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <div>
        <asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional">
            <ContentTemplate>
                <div>
                    <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Submit_Click" />
                </div>
            </ContentTemplate>
        </asp:UpdatePanel>
    </div>
    <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="false">
        <ContentTemplate>
            <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger  ControlID="Timer1" EventName="Tick" />
        </Triggers>
    </asp:UpdatePanel>
    <asp:Timer ID="Timer1" Interval="700" runat="server" OnTick="UpdateTimer_Tick">
    </asp:Timer>
    </form>
</body>

开发者_开发百科

Code Behind

  protected void UpdateTimer_Tick(object sender, EventArgs e)
        {
            Debug.Write("Timer");
            Label1.Text = DateTime.Now.ToString();
        }

        protected void Submit_Click(object sender, EventArgs e)
        {
            Debug.Write("Submit Start ");
            for (int i = 0; i < 1000; i++)
            {
                Thread.Sleep(100);
            }
            Debug.Write("Submit  End   ");
        }

I think the timer is stopped on postback (button-click) and will only start again when that postback returns. One solution to this is to use PageMethods instead of the timer, but you can only make static functions a PageMethod. For the example it would work like this:

[WebMethod()] public static string GetTime(){
    Return DateTime.Now.ToString();
}

html and javascript (jquery):

<body>
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true">
</asp:ScriptManager>
<div>
    <asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional">
        <ContentTemplate>
            <div>
                <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Submit_Click" />
            </div>
        </ContentTemplate>
    </asp:UpdatePanel>
</div>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

<script type="text/javascript">
    function OnSuccess(result, ctrl) { $('#<%=Label1.ClientID %>').html(result); }
    function OnError() { alert("error!"); }
    $(document).ready(function() {
        setInterval(function() { PageMethods.GetTime(OnSuccess, OnError); }, 700)
    });
</script>

</form>
</body>

Don't forget to set EnablePageMethods="true" when using webmethods!

While testing this I noticed the response was slower than the SetTimeout triggering a new ajax call, so the page rapidly builds up running connections, this might be because my development server is a bit slow. To fix this you should not update so frequently, once every 5 seconds will have to do.

I guess the asp.net timer already prevents this behavior: it stops when another ajax call is done. This behavior causes the problem you're experiencing, the button postback blocks the timer updates.