Professional in C# and Visual Basic Part 25. Building on the revolutionary release, adds several key new developer features including AJAX, LINQ, and a new CSS designer in Visual Web Developer 2008. The dramatic reduction in code that developers realized from the more than 50 new server controls in now allows developers the time to make their applications more interactive with AJAX, to work with data in their preferred language with LINQ, and to build visually attractive and consistent standards-based sites with CSS. . | Chapter 4 Validation Server Controls As you work through this chapter you see the different types of validation rules that you can apply to your form elements. Remember that you have no way to validate the truthfulness of the information you collect instead you apply rules that respond to such questions as Is something entered in the text box Is the data entered in the text box in the form of an e-mail address Notice from these questions that you can apply more than a single validation rule to an HTML form element you ll see examples of this later in this chapter . In fact you can apply as many rules to a single element as you want. Applying more rules to elements increases the strictness of the validation applied to the data. Just remember that data collection on the Internet is one of the Internet s most important features so you must make sure that the data you collect has value and meaning. You ensure this by eliminating any chance that the information collected does not abide by the rules you outline. Client-Side versus Server-Side Validation If you are new to Web application development you might not be aware of the difference between client-side and server-side validation. Suppose that the end user clicks the Submit button on a form after filling out some information. What happens in is that this form is packaged in a request and sent to the server where the application resides. At this point in the request response cycle you can run validation checks on the information submitted. If you do this it is called server-side validation because it occurs on the server. On the other hand it is also possible to supply a script usually in the form of JavaScript in the page that is posted to the end user s browser to perform validations on the data entered in the form before the form is posted back to the originating server. If this is the case client-side validation has occurred. Both types of validation have their pros and cons. Active Server Pages .
