Mega Code Archive
Executing Asynchronous Database Commands
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File: App_Code\AsyncDataLayer.cs
using System;
using System.Data;
using System.Data.SqlClient;
using System.Web.Configuration;
using System.Collections.Generic;
public class AsyncDataLayer
{
private static readonly string _connectionString;
private SqlCommand _cmdProducts;
public IAsyncResult BeginGetProducts(AsyncCallback callback, Object state)
{
SqlConnection con = new SqlConnection(_connectionString);
_cmdProducts = new SqlCommand("WAITFOR DELAY '0:0:01';SELECT Title,Director FROM Products", con);
con.Open();
return _cmdProducts.BeginExecuteReader(callback, state, CommandBehavior.CloseConnection);
}
public List<AsyncDataLayer.Product> EndGetProducts(IAsyncResult result)
{
List<AsyncDataLayer.Product> results = new List<AsyncDataLayer.Product>();
SqlDataReader reader = _cmdProducts.EndExecuteReader(result);
while (reader.Read())
{
AsyncDataLayer.Product newProduct = new AsyncDataLayer.Product();
newProduct.Title = (string)reader["Title"];
newProduct.Director = (string)reader["Director"];
results.Add(newProduct);
}
return results;
}
static AsyncDataLayer()
{
_connectionString = WebConfigurationManager.ConnectionStrings["Products"].ConnectionString
+ ";Asynchronous Processing=true";
}
public class Product
{
private string _title;
private string _director;
public string Title
{
get { return _title; }
set { _title = value; }
}
public string Director
{
get { return _director; }
set { _director = value; }
}
}
}
File: Web.config
<configuration>
<connectionStrings>
<add name="Products"
connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|MyDatabase.mdf;Integrated Security=True;User Instance=True" />
</connectionStrings>
</configuration>
File: Default.aspx
<%@ Page Language="C#" Async="true" AsyncTimeout="1" Trace="true" %>
<%@ Import Namespace="System.Threading" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
private AsyncDataLayer dataLayer = new AsyncDataLayer();
void Page_Load()
{
PageAsyncTask task = new PageAsyncTask(BeginGetData, EndGetData, TimeoutData, null, true);
Page.RegisterAsyncTask(task);
Page.ExecuteRegisteredAsyncTasks();
}
IAsyncResult BeginGetData(object sender, EventArgs e, AsyncCallback callback, object state)
{
Trace.Warn("BeginGetData: " + Thread.CurrentThread.GetHashCode());
return dataLayer.BeginGetProducts(callback, state);
}
void EndGetData(IAsyncResult ar)
{
Trace.Warn("EndGetDate: " + Thread.CurrentThread.GetHashCode());
grdProducts.DataSource = dataLayer.EndGetProducts(ar);
grdProducts.DataBind();
}
void TimeoutData(IAsyncResult ar)
{
lblError.Text = "Could not retrieve data!";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Show Page AsyncTask</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Label
id="lblError"
Runat="server" />
<asp:GridView
id="grdProducts"
Runat="server" />
</div>
</form>
</body>
</html>
]]>