ASP.Net

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5 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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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


<%
@
Page
Language
="C#"
AutoEventWireup
="true"
CodeFile
="
Default.aspx.cs
"
Inherits
="_Default" %>



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

<
asp
:
Label
ID
="Label1"
runat
="server"
Text
="Enter the Miles"></
asp
:
Label
>

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 <script> 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
:
TextBox
ID
="txtMiles"
runat
="server"
CssClass
="entry"></
asp
:
TextBox
>

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