INTRODUCTION OF ASP.NET

ASP.Net is a web development platform, which provides a programming model, a comprehensive software infrastructure and various services required to build up robust web application for PC, as well as mobile devices.

ASP.Net works on top of the HTTP protocol and uses the HTTP commands and policies to set a browser-to-server two-way communication and cooperation.

ASP.Net is a part of Microsoft .Net platform. ASP.Net applications are complied codes, written using the extensible and reusable components or objects present in .Net framework. These codes can use the entire hierarchy of classes in .Net framework.

The ASP.Net application codes could be written in either of the following languages:

• Visual Basic .Net (VB.Net)
• C#
• J#
• Jscript

ASP.Net is used to produce interactive, data-driven web applications over the internet. It consists of a large number of controls like text boxes, buttons and labels for assembling, configuring and manipulating code to create HTML pages.

ASP.Net Web Forms Model

ASP.Net web forms extend the event-driven model of interaction to the web applications. The browser submits a web form to the web server and the server returns a full markup page or HTML page in response.

All client side user activities are forwarded to the server for stateful processing. The server processes the output of the client actions and triggers the reactions.

Now, HTTP is a stateless protocol. ASP.Net framework helps in storing the information regarding the state of the application, which consists of: 

• Page state

The page state is the state of the client, i.e., the content of various input fields in the web form.

• Session state

            The session state is the collective obtained from various pages the user visited and worked with, i.e., the overall session state.

To clear the concept, let us take up an example of a shopping cart as follows.

User adds items to a shopping cart. Items are selected from a page, say the items page, and the total collected items and price are shown in a different page, say the cart page. Only HTTP cannot keep track of all the information coming from various pages. ASP.Net session state and server side infrastructure keeps track of the information collected globally over a session.

The ASP.Net runtime carries the page state to and from the server across page requests while generating the ASP.Net runtime codes and incorporates the state of the server side components in hidden fields.

This way the server becomes aware of the overall application state and operates in a two-tiered connected way.

ASP.Net Component Model

The ASP.Net component model provides various building blocks of ASP.Net pages. Basically it is an object model, which describes:

• Server side counterparts of almost all HTML elements or tags, like <form> and <input>.
• Server controls, which help in developing complex user-interface for example the Calendar control or the Gridview control.

ASP.Net is a technology, which works on the .Net framework that contains all web-related functionalities. The .Net framework is made of an object-oriented hierarchy. An ASP.Net web application is made of pages. When a user requests an ASP.Net page, the IIS delegates the processing of the page to the ASP.Net runtime system.

The ASP.Net runtime transforms the .aspx page into an instance of a class, which inherits from the base class Page of the .Net framework. Therefore, each ASP.Net page is an object and all its components i.e., the server-side controls are also objects.