ASP.NET
ASP AND .NET
.Net is a collection of libraries, templates and
services designed to make programming
applications of all kinds, easier, more flexible
(multi platform), and more scalable
ASP.Net is a subset of .Net that contains tools
for developing web based applications
CLIENT/SERVER OVERVIEW
A server is a program that makes services
available to another program (a client)
For instance, A web server such as IIS (Internet
Information Server) or Apache makes web
pages available to a client application such as
a browser
A database server makes data available to
client that makes a valid request
CLIENT/SERVER OVERVIEW CONT.
ASP.Net pages are served from IIS when a
browser requests an .apsx page.
IIS passes the request to .Net which processes
the C# or VB code and ASP controls, makes any
database requests and renders them into xhtml
IIS then sends the rendered page to the
browser that made the request
ASP.NET SERVER/CLIENT
ELEMENTS OF AN ASP PAGE
The Page
Web Form
Html and ASP.Net Controls
Code behind
CSS
THE PAGE
The page is the container for everything else
An ASP application can contain several pages
Usually the starting page is called “Default.aspx”
Every page begins with a directive
This directive tells IIS that the page is an ASP.Net
application
THE WEB FORM
An ASP. Page can have only 1 form.
A key attribute of the form is runat=“server”
which tells IIS to send it to .Net for compiling
and rendering. (Plain html elements are just
passed through to the client without any .net
processing)
All asp controls must be contained within the
form
HTML AND ASP CONTROLS
An ASP.Net page can use
plain xhtml
Xhtml controls (xhtml with the runat=“server”
attribute added)
ASP.Net controls, controls provided by .Net Library
Client side JavaScript
DESIGN AND SOURCE VIEWS
ASP.net pages have two views Design and Source
Design view shows controls approximately as they
will appear on the rendered page (some info
shown here won’t be displayed)
Source view shows the html and the asp.net
controls.
ASP controls are represented as XML fragments
Controls can be added in Design or source views
XML FRAGMENT OF AN ASP CONTROL
CODE BEHIND
ASP.Net allows you to write the code in a
separate file.
This makes code easier to read and maintain
The page directive tells .Net where to find the
code page.
Code can still be placed directly in the web
page if you wish either between tags
or between brackets
CSS
ASP.Net supports CSS and has a good CSS
editor
CSS classes and styles can be added to a ASP
control by using the CssClass attribute
ASP PAGES AND STATE
ASP.Net, like all web pages are stateless.
Every time you click and button or use control that
causes postback the page is re-rendered from the
server
Information is not retained between postbacks
without some additional programming. (Windows
forms have state. They keep their variable values
and contents in RAM)
This has several implications for web application
development that we will have to examine later