افزايش كارآئی برنامه های وب در ASP.NET 2.0

ذخيره داده بازيابی شده از بانك اطلاعاتی در cache
و استفاده از آن بر اساس خواسته كاربر قبل از اتمام تاريخ اعتبار آن

<%@ Page Language="VB" Culture="fa-IR" UICulture="fa-IR" %>
<%@ import Namespace="system.Data" %>
<%@ import Namespace="system.Data.SqlClient" %>
<%@ Import Namespace="System.Web.Configuration" %>

<script runat="server">

Sub cmdApply_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdApply.Click
   Dim ds As DataSet = GetDataSet()
   ds = ds.Copy()

For Each item As ListItem In chkColumns.Items
    If item.Selected Then
       ds.Tables(0).Columns.Remove(item.Text)
   End If
Next
gridPubs.DataSource = ds.Tables(0)
gridPubs.DataBind()
End Sub

'=======================================================================
Function GetDataSet() As DataSet
   Dim dsPubs As DataSet
    If Cache("Titles") Is Nothing Then
      dsPubs = RetrieveData()
      Cache.Insert("Titles", dsPubs, Nothing, DateTime.MaxValue, TimeSpan.FromMinutes(2))
      lblCacheStatus.Text = "ايجاد اطلاعات و ذخيره آنها در cache"
   Else
     dsPubs = CType(Cache("Titles"), DataSet)
      lblCacheStatus.Text = "بازيابی اطلاعات از cache"
End If
Return dsPubs
End Function

'=======================================================================
Function RetrieveData() As DataSet
Dim connectionString As String = _
        WebConfigurationManager.ConnectionStrings("NORTHWNDConnectionString").ConnectionString
Dim SQLSelect As String = "SELECT * FROM Customers"
Dim con As New SqlConnection(connectionString)
Dim cmd As New SqlCommand(SQLSelect, con)
Dim adapter As New SqlDataAdapter(cmd)
Dim ds As New DataSet()
Try
    con.Open()
   adapter.Fill(ds, "Customers")
Finally
    con.Close()
End Try

Return ds
End Function

'======================================================================
Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not Me.IsPostBack Then
Cache.Remove("Titles")
Dim dsPubs As DataSet = GetDataSet()
chkColumns.DataSource = dsPubs.Tables(0).Columns
chkColumns.DataMember = "Item"
chkColumns.DataBind()
End If
End Sub
</script>

'==============================================================
<html xmlns="http://www.w3.org/1999/xhtml" dir="rtl" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body style="font-family: Tahoma">
   <form id="form1" runat="server">
    <div id="DIV1">
      <asp:label id="Label1" runat="server">ستون هائی را كه قصد نمايش آنها در خروجی را نداريد ، انتخاب نمائيد :
      </asp:label>
      <asp:checkboxlist id="chkColumns" runat="server" RepeatColumns="2"></asp:checkboxlist><br />
      <asp:button id="cmdApply" runat="server" Width="144px" Text="فيلتر و نمايش اطلاعات"
              Font-Names="Tahoma" ></asp:button><br />
      <asp:Label ID="lblCacheStatus" runat="server">Hide Columns:</asp:Label>
      <hr />
      <asp:gridview id="gridPubs" runat="server" Width="384px" Height="120px"
             BorderColor="#CC9966" BorderStyle="None"
             BorderWidth="1px" BackColor="White" CellPadding="4"
            Font-Size="X-Small" Font-Names="Verdana" EnableViewState="False">
     <RowStyle ForeColor="#330099" BackColor="White" HorizontalAlign="Left"></RowStyle>
     <HeaderStyle Font-Bold="True" ForeColor="#FFFFCC" BackColor="#990000"></HeaderStyle>
    </asp:gridview>
   </div>
</form>
</body>
</html>