c# data matrix render VIEWSTATE AND SCRIPTING in C#.NET

Generator Data Matrix ECC200 in C#.NET VIEWSTATE AND SCRIPTING

CHAPTER 4 VIEWSTATE AND SCRIPTING
Paint Data Matrix In Visual C#
Using Barcode creation for .NET framework Control to generate, create Data Matrix ECC200 image in Visual Studio .NET applications.
www.OnBarcode.com
Recognize Data Matrix 2d Barcode In Visual C#.NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
The Role of ViewState in ASP.NET
Code 3/9 Drawer In Visual C#.NET
Using Barcode creator for .NET Control to generate, create ANSI/AIM Code 39 image in VS .NET applications.
www.OnBarcode.com
EAN / UCC - 14 Maker In C#.NET
Using Barcode maker for .NET Control to generate, create UCC - 12 image in .NET applications.
www.OnBarcode.com
Creating rich functionality using ASP .NET requires much less code than it does using ASP and other web development environments. You realize a large portion of this savings through the state maintenance the Framework provides. This accounts for, among other things, a drop-down list s capability to maintain the entries in the list across postbacks, all HTML input controls being able to maintain their values across postbacks, and, in more advanced cases, the capability of the DataGrid to maintain its entire HTML table when one of its events causes a postback. The magic of ViewState is accomplished with the aid of a hidden input named __VIEWSTATE. <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUJNzgzNDMwNTMzZGTp0BWhvZM7mmZGfhpcnI4aNOFFbw==" /> All controls on a page can put whatever values they want into this hidden input. The Framework manages these values, basically as a collection of named value pairs. The Framework also manages delimiting values put into ViewState through different controls on the page. It also manages encrypting and decrypting the values before they go to the client and when they re posted back to the server. This means that the Framework provides a complete layer of abstraction between the consumer of ViewState and the details of its actual implementation. This makes using ViewState very easy from custom controls or from the code for a Web Form. Let s start by examining how one of the built-in Web Controls uses ViewState. We ll take a look at the DropDownList control. It maintains the entries in its list across postbacks using ViewState. For each list item that s in the collection of list item objects, the display name, its underlying value, and whether or not it s visible is added to ViewState. ViewState is nothing more than a simple state bag, or collection of tuples. So the DropDownList has an entry in ViewState for its ListItemCollection value, and that value is a collection of tuples, one for each ListItem in the collection. Each of those values, in turn, is a triplet, containing the name, value, and whether or not the field is visible. This organization scheme results in a hierarchical tree of tuple collections, where each control gets its own node of the tree to squirrel away its own values. When the state of the control tree is being saved, each control in the page s control tree has its SaveViewState method called. This is a virtual method of the Control class, and so any control developer can write an override for it. Understand that the Microsoft engineer who wrote the code for the DropDownList did so exactly the same way someone creating a custom Web Control for her own application would, by interacting with the property bag interface. You can see the impact the DropDownList has on the resulting HTML in a couple of different ways. First, there s the trace output report that shows you a control-by-control report of the size each control adds to ViewState (see Figure 4-1).
PDF 417 Creation In Visual C#.NET
Using Barcode creation for .NET Control to generate, create PDF-417 2d barcode image in VS .NET applications.
www.OnBarcode.com
Painting QR Code In Visual C#
Using Barcode encoder for VS .NET Control to generate, create QR Code JIS X 0510 image in .NET applications.
www.OnBarcode.com
CHAPTER 4 VIEWSTATE AND SCRIPTING
Print USS Code 128 In C#
Using Barcode creator for Visual Studio .NET Control to generate, create Code 128 Code Set B image in .NET framework applications.
www.OnBarcode.com
Leitcode Generator In C#.NET
Using Barcode drawer for .NET framework Control to generate, create Leitcode image in VS .NET applications.
www.OnBarcode.com
Figure 4-1. ViewState on the trace output report This provides a good breakdown of the relative sizes, but unfortunately there s no total for the ViewState value. The easiest way to measure this is to use the built-in functionality of your web browser. While viewing any ASP .NET page from the browser, choose View Source. From the instance of Notepad displaying the markup, choose File Save As and write the file out anywhere on your file system (i.e., c:\tmp.htm). Now add EnableViewState=false to the page directive: <%@ Page language="c#" CodeFile="ViewStateIE.aspx.cs" Inherits="APressWebWork.ViewStateIE" EnableViewState=false %> Go back to the browser, refresh the page, view the source again, and write the markup out to another file. The difference in the sizes of these files lets you know the total size of ViewState for the page. Let s look a little more closely at exactly what s stored in ViewState. You ll start by adding a textbox control to a Web Form, and setting its EnableViewState property to false. You ll also add some simple code to the Load event trap, to show whether the request is a postback or a first request. <%@ Page Language="C#" CompileWith="ViewStateIE.aspx.cs" ClassName="ViewStateIE_aspx" Trace="true" %> <html> <head runat="server"> <title>ViewStateIE</title> </head> <body> <form id="form1" runat="server">
Data Matrix 2d Barcode Printer In Objective-C
Using Barcode maker for iPhone Control to generate, create ECC200 image in iPhone applications.
www.OnBarcode.com
Decoding Data Matrix ECC200 In C#.NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Making UCC - 12 In None
Using Barcode drawer for Font Control to generate, create UPC-A image in Font applications.
www.OnBarcode.com
Code39 Maker In Visual Basic .NET
Using Barcode encoder for .NET framework Control to generate, create Code 39 Full ASCII image in Visual Studio .NET applications.
www.OnBarcode.com
PDF-417 2d Barcode Encoder In Java
Using Barcode drawer for BIRT reports Control to generate, create PDF 417 image in Eclipse BIRT applications.
www.OnBarcode.com
Generate EAN 13 In Java
Using Barcode generation for BIRT Control to generate, create European Article Number 13 image in Eclipse BIRT applications.
www.OnBarcode.com
DataMatrix Generator In Java
Using Barcode printer for Java Control to generate, create Data Matrix image in Java applications.
www.OnBarcode.com
Barcode Generation In Java
Using Barcode creation for Eclipse BIRT Control to generate, create Barcode image in BIRT applications.
www.OnBarcode.com
ECC200 Decoder In Visual C#.NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Printing UPC-A In Java
Using Barcode maker for BIRT reports Control to generate, create UPCA image in Eclipse BIRT applications.
www.OnBarcode.com
QR Code JIS X 0510 Decoder In VB.NET
Using Barcode scanner for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Print DataMatrix In Java
Using Barcode creator for Android Control to generate, create ECC200 image in Android applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.