The Module Road Map

Assignment 1 Road Map

We will look at…Internet / World Wide Web

Aspects of their operationThe role of clients and servers

ASPX Page (Web Form)How it is passed between browser and serverThe structure of the pageHow it provides functionality to the browser

The Internet and TCP/IP

Network of networks Defence research in the 60sTCP/IP (Transmission Control Protocol /

Internet Protocol)Allows programs on computers to talk to

each other

The IP AddressUniquely identifies each machine32 bit number made up of four 8 bit numbers Visit http://209.85.227.105/

Assigned in blocks

www.dmu.ac.uk 146.227.160.79www.cse.dmu.ac.uk 146.227.57.2G677 (my server) 146.227.53.94

Name Servershttp://209.85.227.105/ not obviously www.google.com

PortsTCP/IP allows programs on machines to

communicateIP address identifies machineport number identifies programThere is no law that states a specific port must be

used for a service however there are certain ports that traditionally provide services.

80 HTTP (web pages)21 FTP (File transfers)119 NNTP (Network News Transfer Protocol)443 HTTPS (secure web pages)

The World Wide WebUp until about 1989 the Internet existed

quite happily without the World Wide Web

File Transfer Protocol (FTP) TelnetUsenet

World Wide Web - Internet

The Client Server Model

Server v Client Side CodeCode may be added at either end of the process

Client side code runs at browserAction Script (Flash)JavaScript VBScript

Server Side CodeASP.NET (C #)PHPJSP

Telnet

New Process to Consider

XHTML Forms GET and POSTSimple web form (linked from the module web site)

XHTML Form Code

Change POST to GET

http://g519-md.ad.cse.dmu.ac.uk/Request/?txtFirstName=Matthew&txtLastName=Dean&Submit1=submit

Active Server Pages (ASPX)Events User or System Generated

User triggered events 

Click Triggered when a user presses a button 

Selected Index Changed Activated when the user selects an item off a drop down list

  System generated 

Load Runs when the ASPX page is loaded by the serverTypically used to initialise the web form

Unload Runs when the ASPX page is unloaded from the serverTypically used to save data

Handled by event procedures

Anatomy of an ASPX Page

Code may be Embedded in the Web Form

Active Server Controls

Note the tag <asp

Visual Designer

Post Back = FalsePost back is false on the first HTTP request

The browser sends the request to the serverThe server begins processing the pageThe server executes any code associated with

the page load eventThe server runs any code in the page unload

eventAll asp controls are processed by the server and

changed into suitable XHTML controlsThis produces XHTML built from the ASPX pageThe XHTML is sent to the requesting browser

What the Browser Gets…Not the ASPX page but XHTML

Post Back = True

The browser sends the request to the serverThe server begins processing the ASPX pageThe server executes any code associated with the

page load eventThe server executes any code associated with any

events triggered (in this case the click event of the Go button)

The server runs any code in the page unload eventAll asp controls are processed by the server and

changed into suitable XHTML controls (They will be updated with any data from the XHTML version of the form)

This produces XHTML built from the ASPX pageThe XHTML is sent back to the requesting browser

Visual Studio Development ServerVisual Studio starts the development server

VS then launches the browser with the URL

http://localhost:49527/delme1/Default.aspx

Visual Studio makes your computer “talk to itself”

The Future?AJAXAppleWindows 8HTML 5 – Java ScriptFlash