Session[“MyKey1”] = “MyShoppingCartInfo1”;

My assumption was that somehow, the Cookie planted on the client’s browser was in lock step with the IIS server through Session and that even if we did not store Session data, we still had to hook up a Session Provider.  Wrong I am.

I emailed Stefan Schackow, a Microsoft employee who is an expert on all things secure around IIS and ASP.NET and he assured me of this fact.  In fact, I’m going to quote (with his permission) what he told me.

If your app doesn’t use Session anywhere then it doesn’t matter.  We don’t internally rely on session state for anything.  You could literally pull the SessionStateModule out of the configured httpModules list and it would have no effect.

This is a point of confusion for developers because the term “session” is overloaded.  For some of the EJB platforms “session” implies things like authenticated sessions.  But for ASP.NET session is just a bag of data – if your application doesn’t use it, you can completely ignore the feature.

I hope this helps you if you were misguided like I was.

Over the past several years I’ve found myself running into the same problem over and over so I thought I’d blog the solution so at least I don’t waste time figuring it out again.  So, when do you need this?  The answer for me is that I want to be able reference a web site without having to expose the underlying site structure.  For example, on the home page of my business, I want people to be able to type http://73rdstreet.com/Home and be taken to http://www.73rdstreet.com/HomeSite/Home.aspx.

The Symptom

You may see errors that say something like:

Server Error in Application … HTTP Error 404.0 – Not Found

The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.

MapRequestHandler StaticFile

And the screen may show something like this.

If this happens, read on.

Theory

The first thing to understand is that IIS by default will pass to the asp.net process only the requests that have a certain file extension.  That is, aspx,ashx,etc.  Basically, only file extensions that have a handler defined for them to be processed by.  Other URL’s that don’t meet the criteria are not passed to IIS.  This includes no file extension at all.  There is a good reason for this.  One, it makes processing of things like images (jpg’s, gif’s, etc.) faster because they do not every have to be processed through the asp.net worker process.  Secondly, it lowers the exposure of the asp.net worker process so that it is less likely to be compromised.

So, the first thing that has to be done is to tell IIS to pass all requests through using something called Wild Card Mapping.  Then, once this is done, the request comes through to the asp.net worker process regardless of what it is.  As we know, the place that we would have to process this is an HttpModule.  The reason is that since it’s not a page yet, we have no idea what to do with it.  Basically modules let you tap into the request at different stages.  To do the rewrite from ../Home to ../HomeSite/Home.aspx we want to tap into the Application_BeginRequest event.  The Context.RewritePath method is called at that point to force a new path based on what we want (hopefully not hard coded).

After the ReWritePath is set, the page is processed as if is going to the correct page.

How To Set Wild Card Mapping in IIS6

To Set Wild Care Mapping in IIS6 you need to do the following.

Run inetmgr and navigate to the Properties page of the website you want to set.

Then, from the properties page, click the Configuration button as shown below.

Then, press the insert button on the configuration screen and see the following screen and then click on the insert button.

Now, insert your asp.net isapi dll.  On my system, the file is here:  C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll.  Make sure to uncheck the box "Verify that file exists".

That’s it! Now, all requests will be processed through you asp.net pipeline so you will be able to intercept anything on the URL you want.  Be careful though, you may get more than you ask for!

How To Set Wildcard Mapping in IIS7

In IIS7 things are a little different.  First thing you need to do is unlock the config section "handlers". You do this by bring up a DOS prompt and entering the command:

C:\Windows\System32\inetsrv>appcmd.exe unlock config /section:system.webserver/handlers

Then, you can set your wildcard handler in your web.config file as follows.

Now, the default handlers will be executed in your web.config file, and of course, all the defaults for that are in the chain of files that inherits from.  For more details on that, see this FAQ: Configuration Files FAQs (web.config, machine.config…).

You may need to add the wildcard mapper handler to your web.config.  To do this, you would put the following in your web.config

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <handlers>
            <add name="WildCard" path="*" verb="*" type="sampletype" resourceType="Unspecified" />
        </handlers>
    </system.webServer>
</configuration>

Now, you should be set. See the next section for a good method for actually doing the remapping, which is why we went down this path in the first place.

Implementing a URL ReWriter for Mapping ../Home to ../HomeSite/Home.aspx

So, as discussed in the theory section above, you could write your own code to map what you want to where you want it.  You could put in your global.asax some code for the Application_BeginRequest and make a big case statement for everything you want to do.  Well, as we know, that would give your code a bad smell and we don’t want that because soon, you will find yourself using cut and paste and other problematic crutches.

So, to avoid all that, and do what Scott Guthrie suggests, use the open source package UrlRewriter.NET.  It’s light-weight and configurable through a small section in your web.config. Before putting in the what to do, here are the steps to make UrlRewriter work in a very simple way (the way I use it on my company home page.

In your <System.web> of your web.config place a definition for a new config section where you will put your rewrites

<configuration>

    <configSections>

      <section name="rewriter" requirePermission="false" 

        type="Intelligencia.UrlRewriter.Configuration.RewriterConfigurationSectionHandler, Intelligencia.UrlRewriter"/>

Then, put the module that actually does the work of the rewrite as described in the theory section above

<system.web>

   <httpModules>

     <add name="UrlRewriter" 

           type="Intelligencia.UrlRewriter.RewriterHttpModule, Intelligencia.UrlRewriter" />

     </httpModules>

       ..

Then, further down in your web.config put

<system.webServer>

  <validation validateIntegratedModeConfiguration="false"/>

  <modules>

    <add name="UrlRewriter"

         type="Intelligencia.U

<rewriter>

  <rewrite url="~/Home" to="~/pages/Home.aspx"/>

</rewriter>

That’s it!  You are done.  Hope this helps, or at least helps me the next time I’m searching for the same problem (for the 4th time at least).

References:

• http://devtalk.dk/2007/03/19/Wildcard+Mapping+And+URL+Rewriting+On+IIS7.aspx
• http://weblogs.asp.net/scottgu/archive/2007/02/26/tip-trick-url-rewriting-with-asp-net.aspx
• http://urlrewriter.net/
• http://forums.asp.net/t/1240344.aspx
• http://professionalaspnet.com/archive/2007/07/27/Configure-IIS-for-Wildcard-Extensions-in-ASP.NET.aspx
• http://professionalaspnet.com/archive/2007/07/27/Create-an-HttpModule-to-Process-Wildcard-Extension-Mapping-in-ASP.NET.aspx

The Problem

For the third year in a row, Silicon Valley’s Code Camp is happening.  The way I’ve organized the data is that each year I make a fresh new sql server 2005 database catalog.  this means that I have one for 2006, one for 2007 and a new one for 2008.  I want to do a mailing to all people who have registered to previous code camps and who have not registered yet for this code camp.  This way, I can do multiple mailings without worrying about sending to people that who have registered (which would make me look silly for not knowing they registered already).  I do not like when people say things like "Ignore this message if you have registered…".  In addition we will maintain an opt out list so that people who do not want additional emails sent can request that and not worry about us sending more emails.

The Givens

So, since this article is about how to solve the problem with LINQ, I will not go into details of how to create the generic lists of email addresses.  Let’s assume we have methods that give us these 4 lists. They are:

• 2006 Registered Attendees
• 2007 Registered Attendees
• 2008 Registered Attendees
• Opt Out Email List

The Code

Below is the C# version 3.0 (.Net 3.5 and asp.net 3.5) that performs this function described in the problem above.  The next section "The Explanation" gives more details on what i s happening.

   1:  using System.Linq;

   2:   

   3:  /// <summary>

   4:  /// shows all non registered users by going 

   5:  /// through past years and making a

   6:  /// unique query.

   7:  /// </summary>

   8:  /// <returns>List of all non-registered 

   9:  /// code campers form previous years</returns>

  10:  public static List<ListItem> LoadAllUnRegisteredCodeCampUsers()

  11:  {

  12:   

  13:      List<string> codeCampersCurrentYear = 

  14:          GetEmailsFromPreviousYear("CodeCampSV06");

  15:   

  16:      List<string> emailOptOut2008 = 

  17:          GetDoNotRemoveList("CodeCampSV06");

  18:   

  19:      List<string> codeCampers2007 = 

  20:          GetEmailsFromPreviousYear("PASTSV07");

  21:   

  22:      List<string> codeCampers2006 = 

  23:          GetEmailsFromPreviousYear("PASTSV06");

  24:   

  25:      // Make Combined List of 06 and 07 and unique it 

  26:      // (duplicates are removed in Union)

  27:      IEnumerable<string> uniqueNamesQuery =

  28:          codeCampers2006.Union(codeCampers2007).OrderBy(s => s);

  29:   

  30:      var emailListBeforeOptOut = 

  31:          uniqueNamesQuery.Except(codeCampersCurrentYear);

  32:   

  33:      var emaiListAfterOptOut = 

  34:          emailListBeforeOptOut.Except(emailOptOut2008);

  35:   

  36:      List<ListItem>  finalList = new List<ListItem>();

  37:      foreach (string s in emaiListAfterOptOut)

  38:      {

  39:          finalList.Add(new ListItem(s,s));

  40:      }

  41:      return finalList;

  42:  }

  43:   

The Explanation

The first line (1) is required because all the LINQ methods we are using are static extension methods.  This means, that without referencing the LINQ namespace, the methods OrderBy,Except and Union would not be available to us.

Lines 13 to 23 call methods that populate our generic lists of strings.  The reason this is done is because each of these lists come from different SQL Server 2005 database catalogs. This can probably be done in LINQ but I thought it was easier to do it this way.

Line 27 creates a list of unique names.  The Union method has the added benefit of eliminating duplicates.  OrderBy(s=>s) simply creates an annonymous delegate that takes in a string and returns a string so that is what gets sorted.  After giving this some thought, I’m not sure the OrderBy really helps us in anyway but this is a tutorial type article so I’m leaving it in.

Line 33 removes all the people who have asked to be opted out of the email.  It uses the static extension method Except.

Finally, line 36 to 40 creates a generic list of ListItems which is what is returned by the method.  ListItem’s are returned primarily because the calling method shows a list of checkboxes and this makes it easy.

Conclusions

LINQ is a great tool for managing collections.  In this case we demonstrated how to take 4 generic lists of strings (collections), do some simple set operations (union,except,orderby) and produce a list of emails we want to send.  Not only is it simple to code, it’s easy to maintain because the method names are so descriptive.   Hopefully, this will help with your similar programming efforts.  Best of luck.

Introduction

This article shows how to create a modal windows (not a popup) that displays a login windows (asking for username and password) in the middle of whatever asp.net page you are viewing.  It uses the Telerik Modal Radwindow control.  At the end of a successful login, the login dialog redirects the web user to some page designated by the author.  It requires no Javascript programming by the programmer.  Just simple method calls in the asp.net page.

How it Looks to the Web User

When the user press the login button in the upper right corner of the Silicon Valley Code Camp web site, below is the screen they see.

Notice that the screen behind actually fades out and is not able to be clicked by the web user.

The Method Behind Creating the Modal Window

OK, so there is a little bit of javascript you need to add to your page.  Basically, what you do is in your master page, around where you have your login control, you put the following code into your aspx page.

   1:   <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true" />

   2:      <table class="headBar" cellpadding="0" cellspacing="0">

   3:          <tr>

   4:              <td>

   5:                  <div class="headLogo">

   6:                  <asp:HyperLink ID="HomeLink" runat="server" NavigateUrl="Default.aspx">

   7:                      <asp:Image ID="HeadLogo" SkinID="ImageLogo" AlternateText="Silicon Valley codecamp_08"

   8:                          runat="server" />

   9:                  </asp:HyperLink>

  10:                  

  11:                 

  12:                  

  13:                  </div>

  14:              </td>

  15:              <td valign="middle">

  16:                  <span class="headDate">Saturday and Sunday, November 8th & 9th, 2008</span>

  17:              </td>

  18:              <td align="right">

  19:                  <div class="headLogin">

  20:                      <div>

  21:   

  22:                          <script type="text/javascript">

  23:                              //<![CDATA[

  24:                              //show the window

  25:                              function showDialog()

  26:                              {                    

  27:                                  //Force reload in order to guarantee that the onload event handler 

  28:                                  // of the dialog which configures it executes on every show.

  29:                                  var oWnd = window.radopen(null, "DialogWindow");

  30:                                  oWnd.setUrl(oWnd.get_navigateUrl());

  31:                              }

  32:                              

  33:                             

  34:                              // Called when a window is being closed.  (force refresh)

  35:                              function OnClientclose(radWindow)

  36:                              {     

  37:                                   window.location.href = "News.aspx";           

  38:                              }    

  39:                              //]]>            

  40:                          </script>

  41:   

  42:                          <asp:ImageButton ID="IDLoginButton" SkinID="ButtonLogin" 

  43:                              OnClientClick="showDialog();return false;"

  44:                              runat="server" />   

  45:                          <asp:LoginStatus ID="IDLoginStatus1" runat="server" />

  46:                          <asp:LoginName runat="server" ID="IDLoginName1" />

  47:                          <telerik:RadWindowManager ID="Singleton" runat="server">

  48:                              <Windows>

  49:                                  <telerik:RadWindow ID="DialogWindow" Behaviors="Close" 

  50:                                      ReloadOnShow="true" OnClientClose="OnClientclose"

  51:                                      BackColor="Gray" Modal="true" runat="server" Height="250" 

  52:                                      NavigateUrl="./Login.aspx">

  53:                                  </telerik:RadWindow>

  54:                              </Windows>

  55:                          </telerik:RadWindowManager>

  56:                          

  57:                          <asp:HyperLink ID="HyperLinkForgotChangePassword" runat="server" 

  58:                               NavigateUrl="~/PasswordIssues.aspx" Text="Forgot Password?" ></asp:HyperLink>

  59:                          

  60:                      </div>

  61:                      

  62:                  </div>

  63:              </td>

  64:          </tr>

Line 22 to 40 shows the javascript.  Basically, you are calling the Telerik window.radopen method which is associated with the tag on line 49.  It automatically navigates to the login.aspx page which is referenced in line 52.  When the page closes, the javascript on line 37 tells the browser to redirect to the News.aspx page.  The reason I do this is because if you don’t change pages, I’ve found the the login cookie is not set (Authorization cookie).  When this happens, even though the person is logged in, they do not see that they are until a page refresh happens.  Very confusing to the user.

Conclusions

That is really all this is to adding a windows that displays in the middle of your page.  It’s so much nicer than having to send the user to a separate page to login.  They can see where they are as they are logging in.  I hope this helps you.  I find it a very useful technique I can use in lots of web sites.

<asp:TemplateField HeaderText="TemplateUsersId" SortExpression="TemplateUsersId">      <EditItemTemplate>

       <asp:DropDownList ID="DropDownListUser" runat="server" AutoPostBack="False" DataSourceID="SqlDataSourceUser"

            DataTextField="Username" DataValueField="id" SelectedValue='<%# Bind("TemplateUsersId") %>'>

         </asp:DropDownList>

         ..

Notice that even though I’m using Bind rather than eval, the value does not stick.  Well, we always have a reason so I believe it is not working because SelectedValue only has a Get (it’s read only) and the value can not be put back.  So, the solution that works for me is to program the GridView’s Updating Row Event.  That is, get the value from the dropdownlist, and set it in the event.  Here is the code that is working for me.

 /// <summary>    /// This Code Gets the value of the DropDownList in the EditItemTemplate.

    /// </summary>

    /// <param name="sender"></param>

    /// <param name="e"></param>

    protected void GridViewIncomingUrls_RowUpdating(object sender, GridViewUpdateEventArgs e)

    {

        DropDownList dropDownListUser = GridViewIncomingUrls.Rows[e.RowIndex].FindControl("DropDownListUser") as DropDownList;

        e.NewValues["TemplateUsersId"] = dropDownListUser.SelectedValue;

    }

Yee Ha! it works. Hope you don’t have to suffer like me and just bump into this solution

This article shows how to use Expression Builders in ASP.NET 2.0 to retrieve the current logged in user. DataBinding will not work so Expression Builders is the ticket. A small source file is created, the references to web.config are shown and a simple example is built.

The Problem

I recently was looking at unanswered posts in the asp.net forum, specifically this one: http://forums.asp.net/thread/1402259.aspx. I thought I
understood how databinding and expressions worked, but just wanted to check myself. So, I made a simple example
web page just like the post shows. (see below)

<%@ Page Language=”C#” AutoEventWireup=”true” CodeFile=”Default.aspx.cs” Inherits=”_Default” %>
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
<html xmlns=”http://www.w3.org/1999/xhtml”>
<head id=”Head1? runat=”server”>
    <title>Untitled Page</title>
</head>
<body>
    <form id=”form1? runat=”server”>
        <div>
            <asp:GridView ID=”GridView1? runat=”server” AutoGenerateColumns=”False” DataSourceID=”SqlDataSource1?>
                <Columns>
                    <asp:BoundField DataField=”Username” HeaderText=”Username” SortExpression=”Username” />
                </Columns>
            </asp:GridView>
            <asp:SqlDataSource ID=”SqlDataSource1? runat=”server” ConnectionString=”&lt;%$ ConnectionStrings:CodeCampSV06 %&gt;“
                SelectCommand=”SELECT [Username], [Email] FROM [Attendees] WHERE ([Username] = @Username)”>
                <SelectParameters>
                    <asp:Parameter Name=”Username” Type=”String” DefaultValue=”&lt;% User.Identity.Name %&gt;“  />
                </SelectParameters>
            </asp:SqlDataSource>
        </div>
    </form>
</body>
</html>

Then, I ran it through Lutz Roeder’s .NET Reflector and got the following from the code.

private Parameter __BuildControl__control6()
{
    Parameter parameter1 = new Parameter();
    parameter1.Name = “Username”;
    parameter1.Type = TypeCode.String;
    parameter1.DefaultValue = “<% User.Identity.Name %>”;
    return parameter1;
}

It’s pretty obvious that unless there is a username of the literal string "<% User.Identity.Name %>" no records will be find. This simply means that the build provider asp.net uses is not generating any code for us with sqldatasource that will help with the DefaultValue of parameters in a SqlDataSource.

The Solution

Expression Builder to the rescue!

To solve the problem, we need to build a simple expression builder. Without going into all the details of what an expression builder is, all you need to do is put the following code in your app_code directory and call it something like ExpressionBuilderIdentity.cs.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.Compilation;
using System.CodeDom;

public class ExpressionBuilderIdentity : ExpressionBuilder
{
    public override System.CodeDom.CodeExpression GetCodeExpression(
        BoundPropertyEntry entry, object parsedData, ExpressionBuilderContext context)
    {
        CodeTypeReferenceExpression targetClass =
            new CodeTypeReferenceExpression(typeof(ExpressionBuilderIdentity));
        string targetMethod = “GetIdentity”;
        CodeExpression methodParameter =
            new CodePrimitiveExpression(entry.Expression.Trim());
        return new CodeMethodInvokeExpression(
            targetClass, targetMethod, methodParameter);
    }

    public static object GetIdentity(string param)
    {
        string returnString = string.Empty;

        if (param.ToLower().Equals(“name”))
        {
            returnString = HttpContext.Current.User.Identity.Name;
        }

        return returnString;
    }
}

Then, you need to add a reference to it in your web.config as follows:

<compilation debug=“true“>
      <expressionBuilders>
        <add expressionPrefix=“UserIdentity“ type=“ExpressionBuilderIdentity, __code“/>
      </expressionBuilders>
      …

Then, specify the SqlDataSource as follows:

<asp:SqlDataSource ID=”SqlDataSource1″ runat=”server” ConnectionString=”&lt;%$ ConnectionStrings:CodeCampSV06 %&gt;“ SelectCommand=”SELECT [Username], [Email] FROM [Attendees] WHERE ([Username] = @Username)”>
            <SelectParameters>
                <asp:Parameter Name=”Username” Type=”String”
                DefaultValue=”&lt;%$ UserIdentity:name %&gt;“ />
            </SelectParameters>
        </asp:SqlDataSource>

And, Presto, it works!

Summary

Anytime you are using one of the new datasourceID controls, you need to use expressions rather than databinding if you want to reference outside variables. Creating the code is fairly straight forward and lends itself to lots of cool possibilities.

Author: Peter Kellner
Date: August 27th, 2006

This how-to series is my personal exploration into figuring out not just how to make things work, but how they actually work. The theme behind this series is: "If it’s not broken, take it apart and try and figure out why". I plan on covering many issues in ASP.NET 2.0. If you are interested in a particular part of ASP.NET 2.0 that I have not covered, please contact me and time permitting, I’ll see if I can figure out how it works.

Abstract

In this article, a simple asp.net 2.0 page will be taken apart and shown how the actual page class is put together. As we know, when an http request comes into asp.net through the http pipeline that is destined to be a page (file type aspx), the objective of asp.net 2.0 is to create a complete class that encapsulates that page request. That page class is an httpHandler of course.

Example Page

The Example Page simply has three Labels and one Button. The Labels and buttons will be as follows:

• Label1 – Gets Date and Time set in Page_Load event
• Label2 – Gets Date and Time using databinding
• Label3 – Gets Date and Time when button is pressed
• Button1 – Puts Date and Time in Label3 as well as executes DataBind on control Label2

Here is the page code below. (CodeBehindSample1.aspx)

< %@ Page Language="C#" AutoEventWireup="true" CodeFile="CodeBehindSample1.aspx.cs" Inherits="CodeBehindSample1" %>

< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp :Label ID="Label1" runat="server" ></asp>
        <asp :Label ID="Label2" runat="server"
          Text='<%# DateTime.Now.ToLongTimeString() %>'></asp>
        <asp :Label ID="Label3" runat="server" Text="Label"></asp>
        <asp :Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />

    </div>
    </form>
</body>
</html>

And the codebehind file itself. ((CodeBehindSample1.aspx.cs)

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class CodeBehindSample1 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Label1.Text = DateTime.Now.ToLongTimeString();
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        Label3.Text = DateTime.Now.ToLongTimeString();
        Label2.DataBind();
    }
}

When the project is built that includes this page above, an .net assembly is created that represents the above page. The files are stored in a directory called something like C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\pagecache\6b6b75e0\f0cbf892. There are two files that are worth looking at.

App_Web_qlh7npdn.1.cs and App_Web_qlh7npdn.0.cs (I will refer to them as 1.cs and 0.cs from here on out).

0.cs has two classes of interest to talk about.

The first one, (1.cs) declared as "public partial class CodeBehindSample1 : System.Web.SessionState.IRequiresSessionState {" includes a definition for each of the controls declared on the aspx page. It gives us a reference to Profile and ApplicationInstance from the Context of the application (originally created when the request came in).

The second one, (0.cs) which is created in the namespace ASP, (in our case is called ASP.codebehindsample1_aspx which is because of what is defined in the Page tag Inherits) is the full page that represents this request. It has a method that builds each control including databinding. Notice that this class actually inherits from the first one mentioned (1.cs). The actual declaration is as follows: "public class codebehindsample1_aspx : global::CodeBehindSample1, System.Web.IHttpHandler {"

There are several things to notice about this generated code. Here is a list to pay attention to.

• In the code generated for the button (private global::System.Web.UI.WebControls.Button @__BuildControlButton1() {
  
  global::System.Web.UI.WebControls.Button @__ctrl;) notice that the text is set to "Button" and the ID is set to Button1. This is the code created from the attribute definition in the aspx file.
• Notice how the event handler Button1_Click is created in code. @__ctrl.Click += new System.EventHandler(this.Button1_Click);
• For databinding on Label2, notice that the member "public void @__DataBindingLabel2(object sender, System.EventArgs e) {". You can see how the datacontainer is created, then the dataBindingExpressionBuilderTarget.Text is set to the current data and time.
  

Conclusion

In conclusion, you can see that at the end of the day, one class is created (ASP.codebehindsample1_aspx) that fully represents the page. Attributes that are set declaratively in the page are turned into code in the 0.cs file, and databinding is performed using a artificially generated event. Below, I’ve pasted both the code for 0.cs and 1.cs which should be helpful and instructive

0.cs

//------------------------------------------------------------------------------
// <auto -generated>
//     This code was generated by a tool.
//     Runtime Version:2.0.50727.42
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto>
//------------------------------------------------------------------------------

public partial class CodeBehindSample1 : System.Web.SessionState.IRequiresSessionState {

    protected global::System.Web.UI.WebControls.Label Label1;
    protected global::System.Web.UI.WebControls.Label Label2;
    protected global::System.Web.UI.WebControls.Label Label3;
    protected global::System.Web.UI.WebControls.Button Button1;
    protected global::System.Web.UI.HtmlControls.HtmlForm form1;

    protected System.Web.Profile.DefaultProfile Profile {

        get {
            return ((System.Web.Profile.DefaultProfile)(this.Context.Profile));
        }
    }

    protected System.Web.HttpApplication ApplicationInstance {
        get {
            return ((System.Web.HttpApplication)(this.Context.ApplicationInstance));
        }
    }
}
namespace ASP {

    using System.Web.Profile;
    using System.Text.RegularExpressions;
    using System.Web.Caching;
    using System.Configuration;
    using System.Collections.Specialized;
    using System.Web.UI.HtmlControls;
    using System.Web.UI.WebControls
    using System.Web.UI;
    using System.Collections;
    using System;
    using System.Web.Security;
    using System.Web;
    using System.Web.SessionState;
    using System.Text;

    [System.Runtime.CompilerServices.CompilerGlobalScopeAttribute()]
    public class codebehindsample1_aspx : global::CodeBehindSample1,
           System.Web.IHttpHandler {

        private static bool @__initialized;

        private static object @__fileDependencies;

        public codebehindsample1_aspx() {
            string[] dependencies;

            ((System.Web.UI.Page)(this)).AppRelativeVirtualPath =
            "~/CodeBehindSample1.aspx";

            #line default
            #line hidden
            if ((global::ASP.codebehindsample1_aspx.@__initialized == false)) {
                dependencies = new string[2];
                dependencies[0] = "~/CodeBehindSample1.aspx";
                dependencies[1] = "~/CodeBehindSample1.aspx.cs";
                global::ASP.codebehindsample1_aspx.@__fileDependencies =
                this.GetWrappedFileDependencies(dependencies);
                global::ASP.codebehindsample1_aspx.@__initialized = true;
            }
            this.Server.ScriptTimeout = 30000000;
        }

        private global::System.Web.UI.HtmlControls.HtmlTitle
             @__BuildControl__control3() {
            global::System.Web.UI.HtmlControls.HtmlTitle @__ctrl;

            @__ctrl = new global::System.Web.UI.HtmlControls.HtmlTitle();

            System.Web.UI.IParserAccessor @__parser =
            ((System.Web.UI.IParserAccessor)(@__ctrl));

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("Untitled Page"));

            return @__ctrl;
        }

        private global::System.Web.UI.HtmlControls.HtmlHead @__BuildControl__control2() {
            global::System.Web.UI.HtmlControls.HtmlHead @__ctrl;

            @__ctrl = new global::System.Web.UI.HtmlControls.HtmlHead("head");

            global::System.Web.UI.HtmlControls.HtmlTitle @__ctrl1;

            @__ctrl1 = this.@__BuildControl__control3();

            System.Web.UI.IParserAccessor @__parser =
               ((System.Web.UI.IParserAccessor)(@__ctrl));

            @__parser.AddParsedSubObject(@__ctrl1);

            return @__ctrl;
        }

        private global::System.Web.UI.WebControls.Label @__BuildControlLabel1() {
            global::System.Web.UI.WebControls.Label @__ctrl;

            @__ctrl = new global::System.Web.UI.WebControls.Label();

            this.Label1 = @__ctrl;
            @__ctrl.ApplyStyleSheetSkin(this);

            @__ctrl.ID = "Label1";

            #line default
            #line hidden
            return @__ctrl;
        }

        private global::System.Web.UI.WebControls.Label @__BuildControlLabel2() {
            global::System.Web.UI.WebControls.Label @__ctrl;

            @__ctrl = new global::System.Web.UI.WebControls.Label();

            this.Label2 = @__ctrl;
            @__ctrl.ApplyStyleSheetSkin(this);

            @__ctrl.ID = "Label2";

            @__ctrl.DataBinding += new System.EventHandler(this.@__DataBindingLabel2);

            #line default
            #line hidden
            return @__ctrl;
        }

        public void @__DataBindingLabel2(object sender, System.EventArgs e) {
            System.Web.UI.WebControls.Label dataBindingExpressionBuilderTarget;
            System.Web.UI.Page Container;
            dataBindingExpressionBuilderTarget =
            ((System.Web.UI.WebControls.Label)(sender));
            Container =
            ((System.Web.UI.Page)(dataBindingExpressionBuilderTarget.BindingContainer));

            dataBindingExpressionBuilderTarget.Text =
            System.Convert.ToString( DateTime.Now.ToLongTimeString() ,
             System.Globalization.CultureInfo.CurrentCulture);

        }

        private global::System.Web.UI.WebControls.Label @__BuildControlLabel3() {
            global::System.Web.UI.WebControls.Label @__ctrl;

            @__ctrl = new global::System.Web.UI.WebControls.Label();

            this.Label3 = @__ctrl;
            @__ctrl.ApplyStyleSheetSkin(this);

            @__ctrl.ID = "Label3";

            @__ctrl.Text = "Label";

            #line default
            #line hidden
            return @__ctrl;
        }

        private global::System.Web.UI.WebControls.Button @__BuildControlButton1() {
            global::System.Web.UI.WebControls.Button @__ctrl;

            @__ctrl = new global::System.Web.UI.WebControls.Button();

            this.Button1 = @__ctrl;
            @__ctrl.ApplyStyleSheetSkin(this);

            @__ctrl.ID = "Button1";

            @__ctrl.Text = "Button";

            #line default
            #line hidden

            @__ctrl.Click += new System.EventHandler(this.Button1_Click);

            return @__ctrl;
        }

        private global::System.Web.UI.HtmlControls.HtmlForm @__BuildControlform1() {
            global::System.Web.UI.HtmlControls.HtmlForm @__ctrl;

            @__ctrl = new global::System.Web.UI.HtmlControls.HtmlForm();

            this.form1 = @__ctrl;

            @__ctrl.ID = "form1";

            System.Web.UI.IParserAccessor @__parser =
            ((System.Web.UI.IParserAccessor)(@__ctrl));

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n    <div>\r\n    "));

            global::System.Web.UI.WebControls.Label @__ctrl1;

            @__ctrl1 = this.@__BuildControlLabel1();

            @__parser.AddParsedSubObject(@__ctrl1);

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n        "));

            global::System.Web.UI.WebControls.Label @__ctrl2;

            @__ctrl2 = this.@__BuildControlLabel2();

            @__parser.AddParsedSubObject(@__ctrl2);

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n        "));

            global::System.Web.UI.WebControls.Label @__ctrl3;

            @__ctrl3 = this.@__BuildControlLabel3();

            @__parser.AddParsedSubObject(@__ctrl3);

            #line default
            #line hidden

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n        "));

            global::System.Web.UI.WebControls.Button @__ctrl4;

            @__ctrl4 = this.@__BuildControlButton1();

            #line default
            #line hidden

            @__parser.AddParsedSubObject(@__ctrl4);

            #line default
            #line hidden

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n       \r\n    </div>\r\n    "));

            #line default
            #line hidden
            return @__ctrl;
        }

        private void @__BuildControlTree(codebehindsample1_aspx @__ctrl) {

            this.InitializeCulture();

            System.Web.UI.IParserAccessor @__parser = ((System.Web.UI.IParserAccessor)(@__ctrl));

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl
            ("\r\n\r\n< !DOCTYPE html
            PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\"
             \"http://www.w3" +
                        ".org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">
                        \r\n\r\n<html xmlns=\"http://www.w3.org/1" +
                        "999/xhtml\" >\r\n"));

            global::System.Web.UI.HtmlControls.HtmlHead @__ctrl1;

            @__ctrl1 = this.@__BuildControl__control2();

            #line default
            #line hidden

            @__parser.AddParsedSubObject(@__ctrl1);

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n<body>\r\n    "));

            global::System.Web.UI.HtmlControls.HtmlForm @__ctrl2;

            @__ctrl2 = this.@__BuildControlform1();

            @__parser.AddParsedSubObject(@__ctrl2);

            @__parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n</body>\r\n</html>\r\n"));

        }

        protected override void FrameworkInitialize() {
            base.FrameworkInitialize();
            this.@__BuildControlTree(this);
            this.AddWrappedFileDependencies(global::ASP.codebehindsample1_aspx.@__fileDependencies);
            this.Request.ValidateInput();
        }

        public override int GetTypeHashCode() {
            return -956737817;
        }

        public override void ProcessRequest(System.Web.HttpContext context) {
            base.ProcessRequest(context);
        }
    }
}

1.cs

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class CodeBehindSample1 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Label1.Text = DateTime.Now.ToLongTimeString();
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        Label3.Text = DateTime.Now.ToLongTimeString();
        Label2.DataBind();
    }
}

#line default
#line hidden