1. ASP.NET WEB Applications

2. ASP.NET  Web application framework developed by Microsoft  Build dynamic data driven web applications and web services  Subset of.NET framework  A set of classes  Successor of ASP (Active Server Pages)  Several new properties

3. Web Application  An application accessed by users through a web browser  Google.com  isbank.com.tr  Alternative technologies for building web applications  PHP, Java, Ruby on Rails, Perl…  We will stick with ASP.NET and C#

4. Advantages of Web Aplications  Installed just on server  Desktop applications need to be installed on every client computer  Easy to maintain, support, update  Think you find a bug on your application  Only a browser is required on client machines  With Internet connection  Cross platform support  Linux, Mac, Windows

5. Web Aplication Arcitecture  Client / Server architecture  Client needs a browser that can understand HTML  On server side web application runs under Internet Information Services (IIS)  IIS process the requests and return the page to the client through html Internet HTTP Protocol Web Application (IIS) Server

6. Create a web application  Select new project  Web application  Default.aspx  Design (visual)  Source (html)  Code behind site (default.aspx.cs)  Designer file (auto generated)

7. ViewState  Web applications run on HTTP protocol  Http protocol is a stateless protocol  It does not retain state between user requests  Web forms have a short life time 1. A web form is created when a request came 2. Events processed 3. Html generated and sent to the client 4. Web form is destroyed  Lets see an example

8. ViewState  To make web form remember information between requests, ViewState varibles are used  The ViewState date travels with every request and response between the client and server  ViewState can store any object  You can give any name to the object  Stored under the hidden field  Under base64 encode format  Although the information in a hidden field is not displayed, users can see the contents of the control by viewing the page's source.  Do not store sensitive information in a HiddenField control, such as user IDs, passwords, or credit card information.HiddenField  All ASP.NET controls use the ViewState internally  Big advantage over old ASP