Getting Started with ASP.NET

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Getting Started with ASP.NET
Beginning ASP.NET 4.0 in C# 2010
Chapters 5 and 6
1
Objectives
You will be able to
 Create a very simple web application in
Visual Studio 2010.
 Dynamically alter contents of a page.
 Get and process text input from the user.
 Understand the relationship between
what you write in Visual Studio and what
the browser receives from the server.
2
ASP.NET


ASP.NET permits us to dynamically create
content for a web page using code that runs on
the server.
Start with a file of text similar to HTML.




Can include real HTML.
We can modify any properties of page elements at
run time.
Server translates this pseudo-HTML into real
HTML which it sends to the browser.
We can provide code to respond to events such
as button clicks.
3
Hello, World!



Let’s start with a “Hello, World” ASP.NET
application.
Get past the startup hurdles before trying
to write real web application code.
We will use Visual Studio’s built in web
server to test and demonstrate our web
application code.
4
Creating a New Web App

In Visual Studio 2010

File > New Web Site
(NOT New project)
5
Empty Web Site
Check this setting
Web Site Name
6
View Solution Explorer
7
The Solution Explorer
8
A New “Empty” Web Site


Visual Studio is ambiguous about “project”
There is no project file
such as you might have seen for Visual Studio
Windows programs.
9
A New “Empty” Web Site

There is a pair of “solution” files in the
Projects directory.
10
The Solution Files

Hello.sln holds Visual Studio settings
associated with this web site (project).

You can look at it with WordPad.

Hello.suo is a binary file

These files are used only by Visual Studio.




Not part of the web app.
Not deployed to a web server.
Both of these files can be reproduced at
any time if they are deleted.
Can generally be ignored.
11
The Web Site Directory
C:\Documents and Settings\Rollins\My Documents\
Visual Studio 2010\WebSites\Hello



These files are the web app.
Will be deployed to the web server.
Will be in a virtual directory on the
Internet.
12
The web.config File
Double click to open
in VS editor
13
The web.config File

Every ASP.NET web app has an XML
configuration file called web.config.


Holds information used by the server and
(possibly) by application code.


See page 163 and following.
Can be edited with any plain text editor.


ASCII text
Even on the server
We will learn more about config files
throughout the course.

Can ignore for now.
14
Initial web.config
15
Adding a Web Page
16
Add File Default.aspx
Note file name.
This is the usual starting page for an ASP.NET web site.
17
Default.aspx
18
Default.aspx.cs
Visual Studio has also created the “code behind” file, Default.aspx.cs
19
Default.aspx.cs
The initial file doesn’t do anything.
20
The Design View
A WYSIWYG editor for web pages.
View > Toolbox
21
The Design Surface
Click here to see Source view.
22
Source View
Click here to return to Design view.
23
Design View
Click inside Div box.
Then double click on Label in Toolbox.
24
Add a Label
Right click on Label.
Select Properties.
Set Text property to “Hello, World!”
25
Label Properties
Click here to view in browser.
26
Debugging Not Enabled
Click OK.
27
Page in Chrome
28
What We Wrote
29
What the Browser Received
30
What’s happening here?

When a browser requests an aspx page
from an IIS (Microsoft) web server, IIS
retrieves the file from the virtual
directory and passes it to ASPX for
processing.
31
What’s happening here?

ASPX translated what we wrote into what
the browser saw.


Using the visual designer, we wrote the
HTML-like code shown on a previous slide.
Visual Studio’s built-in IIS web server
translated that code into the real HTML code
that the browser received.


Note that there is a single HTML form.
The browser rendered the HTML as the page
that we saw.
32
Translating ASPX to HTML

All <% ... %> tags are instructions to
the server.

Removed and processed by the server.
<%@ Page Language="C#" AutoEventWireup="true"
CodeFile="Default.aspx.cs" Inherits="_Default" %>
33
Translating ASPX to HTML

All <asp:xxx




> tags are ASPX controls.
Replaced by HTML as the aspx file is
processed by ASPX on the server.
ASPX compiles an object corresponding to
each control.
The object emits HTML text as the page is
rendered on the server.
All HTML text is passed to the browser
unchanged.
34
Translating ASPX to HTML
ASPX
HTML
<span id="Label1">Hello, World!</span>
35
Add Some Style




In Design view, right click on the label and select
Properties.
Properties window will appear.
Expand Font and set Font properties
 Bold: True
 Name: Arial
 Size: XX-Large
Set ForeColor property to Red
36
Set Properties
37
Give the Page a Title
Select
DOCUMENT
Click the Play button to display the page in the browser.
38
Our Page in Chrome
Title
39
What We Wrote
40
What the Browser Received
41
The Code-Behind File



View Solution Explorer
Expand Default.aspx
Double click on Default.aspx.cs to open
the source code file in an editor window.
42
Class _Default
Page_Load will be executed before
the page is rendered on the server.
43
Dynamically Alter the Page
44
The New Version in Chrome
45
What We Wrote
Default.aspx has not changed.
46
What the Browser Received
The text inside the <span> is different.
47
What’s happening here?

The server read file Default.aspx

The server instantiated the label as an object.



The server read and compiled Default.aspx.cs, and
then invoked our Page_Load method.
Our code modified properties of the label object.



Lable1.Text
Label1.ForeColor
The server invoked a method of the label object.


With the properties that we had set.
Output yourself as HTML.
The browser saw the resulting HTML.
48
Getting User Input


Let’s modify the page to get the user’s name
and customize the greeting for the user.
Back in the Designer




View the toolbox
Position the cursor in front of Hello, World!
Press Enter several times to add some space
above Hello, World.
Position the cursor at the top of the div box.
49
Getting User Input



In the Toolbox, double click Label to add a
Label to the page.
Press Enter
In the Toolbox, double click TextBox.


You may need to scroll down in the Toolbox.
Resize the Textbox as shown on the next
slide.
50
Getting User Input
51
Modify the Page in the Designer

Give the original label a name.



lblGreeting in its (ID) Property
Set text for new label to “Please enter
your name then click OK.”
Set ID property of the TextBox to
tbName.
52
In the Designer
53
Add a Button





Position the cursor between the textbox
and Hello, World!
Double click Button in ToolBox.
Set its Text property to OK.
Set its ID to btnOK.
Resize the button, making it a bit larger.
54
Add a Button
55
Add a Button


Double click on the button to generate an
event handler.
Add code to the event handler as shown
in the next slide.
56
The Button-click Event Handler
57
The Page in Chrome
Enter your name and then click OK.
58
After Clicking OK
59
What We Wrote
What the Browser Saw Initially
Scroll down.
61
What the Browser Saw Initially
62
What the Browser Saw After the Click
Scroll down.
63
What the Browser Saw After the Click
64
Files

Let’s see what files we have created.
The WebSites Directory
65
Directory Hello

These files are plain text files.


Can open in NotePad
These files are the web app.

Can be copied to an IIS web server and
accessed on the Internet
66
Projects Directory
67
Solution Files
These files are used by Visual Studio to manage the project.
Remember settings, etc.
Don’t need to look at them. Must not modify them.
Can be deleted. Visual Studio will recreate them the next
time we open the web site.
68
Assignment



Review the slides for this presentation.
Do the examples from this lecture for
yourself if you didn’t do them in class.
Read (Skim) Chapters 1 - 5 of
Beginning ASP.NET 4.0 in C# 2010
69
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