Question

i created web page with dropdownlist and two gridview and on selectedindex changed event i fill the both of these gridview but in the running the both of gridview take long time to be filled.

Note:one of this gridview i created its datasource by code.
here my code snippet:

    protected void _ddlPLCs_SelectedIndexChanged(object sender, EventArgs e)
{
    DataTable dtStatus = new DataTable();

    dtStatus = DBLayer.getMachineNameIPStatusPlCByName(_ddlPLCs.SelectedValue);
    dtStatus.Columns.Add("Status", typeof(String));
    foreach (DataRow row in dtStatus.Rows)
    {
        if (LogicLayer.checkmachineStatus(row["machineIP"].ToString()))
            row["Status"] = "Online";
        else
            row["Status"] = "offline";

    }

    GVStatus.DataSource = dtStatus;
    GVStatus.DataBind();
    if (_ddlPLCs.SelectedValue.Contains('-'))
    {
        _dsPLCs.SelectParameters.Clear();
        _dsPLCs.SelectParameters.Add("PLCID","0");
        _dsPLCs.DataBind();
    }
    else
    {
        _dsPLCs.SelectParameters.Clear();
        _dsPLCs.SelectParameters.Add("PLCID", DBLayer.getPlCIDByName(_ddlPLCs.SelectedValue).ToString());
        _dsPLCs.DataBind();
    }            


}

pleas help me

Answer 1

Looking at the code, I think the problem is in this method:

LogicLayer.checkmachineStatus()

I have a hunch that this actually makes a network request to remote machines/devices to determine their status. This is going to be slow, especially if you have machines that might not be online and you have to wait for them to timeout.

If this is the culprit, what you want to do instead is build a service that runs on your server. The service should continually make these checks in the background and update a database table with the results. You probably want to include a timestamp for the last check in the table. It might even be worth inserting rather than updating, so that you have history of when status’s were at different values. Your ASP.Net code should then just show the database table.