Tuesday, 29 December 2015

Quick Start :To ASP.NET

Quick Start :To ASP.NET

After this short excursion with some background information on the .NET Framework, we will now focus on ASP.NET.

File name extensions

Web applications written with ASP.NET will consist of many files with different file name extensions. The most common are listed here. Native ASP.NET files by default have the extension .aspx (which is, of course, an extension to .asp) or .ascx. Web Services normally have the extension .asmx.
Your file names containing the business logic will depend on the language you use. So, for example, a C# file would have the extension .aspx.cs. You already learned about the configuration file Web.Config.
Another one worth mentioning is the ASP.NET application file Global.asax - in the ASP world formerly known as Global.asa. But now there is also a code behind file Global.asax.vb, for example, if the file contains Visual Basic.NET code. Global.asax is an optional file that resides in the root directory of your application, and it contains global logic for your application.

All of these are text files

All of these files are text files, and therefore human readable and writeable.

The easiest way to start

The easiest way to start with ASP.NET is to take a simple ASP page and change the file name extension to .aspx.

Page Syntax

Here is quick introduction of syntax used in ASP.NET


You can use directives to specify optional settings used by the page compiler when processing ASP.NET files. For each directive you can set different attributes. One example is the language directive at the beginning of a page defining the default programming language.

Code Declaration Blocks

Code declaration blocks are lines of code enclosed in <script> tags. They contain the runat=server attribute, which tells ASP.NET that these controls can be accessed on the server and on the client. Optionally you can specify the language for the block. The code block itself consists of the definition of member variables and methods.

Code Render Blocks

Render blocks contain inline code or inline expressions enclosed by the character sequences shown here. The language used inside those blocks could be specified through a directive like the one shown before.

HTML Control Syntax

You can declare several standard HTML elements as HTML server controls. Use the element as you are familiar with in HTML and add the attribute runat=server. This causes the HTML element to be treated as a server control. It is now programmatically accessible by using a unique ID. HTML server controls must reside within a <form> section that also has the attribute runat=server.

Custom Control Syntax

There are two different kinds of custom controls. On the one hand there are the controls that ship with .NET, and on the other hand you can create your own custom controls. Using custom server controls is the best way to encapsulate common programmatic functionality.
Just specify elements as you did with HTML elements, but add a tag prefix, which is an alias for the fully qualified namespace of the control. Again you must include the runat=server attribute. If you want to get programmatic access to the control, just add an Id attribute.
You can include properties for each server control to characterize its behavior. For example, you can set the maximum length of a TextBox. Those properties might have sub properties; you know this principle from HTML. Now you have the ability to specify, for example, the size and type of the font you use (font-size and font-type).
The last attribute is dedicated to event binding. This can be used to bind the control to a specific event. If you implement your own method MyClick, this method will be executed when the corresponding button is clicked if you use the server control event binding shown in the slide.

Data Binding Expression

You can create bindings between server controls and data sources. The data binding expression is enclosed by the character sequences <%# and %>. The data-binding model provided by ASP.NET is hierarchical. That means you can create bindings between server control properties and superior data sources.

Server-side Object Tags

If you need to create an instance of an object on the server, use server-side object tags. When the page is compiled, an instance of the specified object is created. To specify the object use the identifier attribute. You can declare (and instantiate) .NET objects using class as the identifier, and COM objects using either progid or classid.

Server-side Include Directives

With server-side include directives you can include raw contents of a file anywhere in your ASP.NET file. Specify the type of the path to filename with the pathtype attribute. Use either File, when specifying a relative path, or Virtual, when using a full virtual path.

Server-side Comments

To prevent server code from executing, use these character sequences to comment it out. You can comment out full blocks - not just single lines.
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