Transcript Lecture 3
IS1811 Multimedia Development
for Internet Applications
Lecture 3: Introduction to basic Web and
Internet Technologies
Rob Gleasure
[email protected]
http://girtab.ucc.ie/rgleasure/index.html
IS1811
Today’s class
TCP/IP and OSI models
Http and file transfer protocols
Common browsers
Internet demographics
Introduction to HTML
TCP/IP
Transmission Control Protocol / Internet Protocol (TCP/IP) is the
communication protocol for the Internet.
Your browser uses TCP/IP to access Internet servers, and
servers use TCP/IP to send HTML back to your browser.
An Internet address or IP address "193.120.116.180" is a part of the
standard TCP/IP protocol, as is the domain name www.website.com
The IP part encompasses the connectionless packet-switching
discussed in lecture 2
OSI Model
Open Systems Interconnection (OSI) Basic Reference Model
Developed by International Organisation for Standardization (ISO) in
1984 to provide a reference model for the complex aspects related
to network communication
OSI and TCP/IP Models
OSI and TCP/IP Models
Both models divide the different functions and services provided by
network hardware and software into discrete and separate layers.
The benefits of this?
Modular engineering (may be built in chunks)
More simple to teach and learn network technologies
Easier to isolate problems
Allows vendors to focus on just the layer(s) in which their
hardware or software is implemented and be able to create
products that are compatible, standardized and interoperable.
Universal Resource Locators (URL)
URLs
Used to identify resources on the Internet
Are also called “Uniform Resource Locators”
Have the following general format:
network-protocol:resource-location/file
Networking protocols can be
http, ftp, gopher, telnet, file, mailto, news
Resource location
//domain_name/directory/file
E.g. http://www.site.ie/en/index.html
HTTP
Hypertext Transfer Protocol (HTTP)
Designed within the application layer of the TCP/IP architecture
to distribute hypertext documents
Works on the client-server principle and is the foundation of
data communication on the Web
Files are sent with accompanying meta-data headers
describing details such as the content type, last modified date,
etc
Composed of standards supported by W3C
Currently, version 1.1 is most commonly used
HTTP (continued)
Hypertext Transfer Protocol (HTTP)
HTTP has 2 important features:
As well as basic web files such as html documents, a
server can also return other miscellaneous data from
applications running on a server to a client, e.g. database
records
It can also pass data sent from a client to various serverside CGI programs for additional processing via the HTTP
URL
FTP
File Transfer Protocol (FTP)
Used to copy a file from one machine to another
Also works within the application layer of the TCP/IP
architecture and also client-server based
Unlike HTTP, FTP transfers include no meta-data
Uses two connections: one to establish
communication/exchange commands and one to stream data
Less secure
Tends to be blocked by firewalls
Other Protocols
Telnet
Allows you to use the resources of a distant computer
somewhere else in the world
often used to share the power of a large single machine
amongst many remote users using less advanced terminals
Mailto
Allows emails to be send directly from an email interface within
the browser, e.g. mailto:[email protected]
Common File Types
Types of webpage
.html
.xhtml
.mhtml
.xml
Often academic sites or sites where large volumes of
information is managed and shared.
.asp/aspx
Created using Microsoft Visual Studio
Often used for elaborate or high-processing sites, or those
where large amounts of user input is received.
.php
Similar suitability as .aspx
Common File Types
Types of image
.gif
Graphics Interchange Format
Traditionally the “Darling of the web”
Largely used for icons or simple images.
Lessening of importance as bandwidth increases in Internet
users. Still very common though.
Common File Types
Types of image
.jpeg
Joint Photographic Experts Group
Still the most common format used for photographs
Same format as digital cameras use
Issues with “lossy” compression
Common File Types
Types of image
.png
Portable Network Graphic
Put forward by w3c as an alternative format
Lossless compression
Variable quality/file-size
Gaining popularity all the time
What browsers are out there?
The Web consortium generally consider Internet Explorer (IE),
Firefox, Chrome, Opera and Safari to the main families of
browsers
IE
Firefox
Chrome
Safari
Opera
July
2014
8.5 %
24.9 %
59.8 %
3.5 %
1.7 %
July
2012
16.3 %
33.7 %
42.9 %
3.9 %
2.1 %
July
2010
30.4 %
46.4 %
16.7 %
3.4 %
2.3 %
July
2008
52.8 %
41.0 %
-
2.5 %
1.9 %
Statistics from http://www.w3schools.com/browsers/browsers_stats.asp
What Are Mobile Applications?
Mobile applications are applications and/or services that are used
on a mobile device
Mobile applications can be developed to be
Mobile Web (viewed on browsers within mobile devices)
Native (Installed as programs on mobile devices)
Growth of Mobile Applications
Mobile Applications Internationally
Internet Usage
Taken from http://www.internetworldstats.com/stats.htm
Internet Usage
Taken from http://www.internetworldstats.com/stats.htm
Internet Usage
Taken from http://www.internetworldstats.com/stats.htm
Hypertext Markup Language (HTML)
What is HTML?
HTML stands for Hyper Text Markup Language
An HTML file is a text file containing simple markup tags
These tags tell the Web browser how to display the page
An HTML file must have an .htm or .html file extension
An HTML file can be created using a simple text editor
We’ll be using Notepad or Notepad++
HTML (continued)
How does HTML work?
The basic principle is to “wrap” everything in tags.
These tags are organised in a concentric manner.
A simple web page
Open up either Internet Explorer or Firefox (double-click on either
OR
on your desktop)
Open up Notepad
go to start menu all programs accessories notepad
Save the file to the desktop with the name “hello.html”
Make sure you save it as “All Files”.
A simple web page
Type or copy-and-paste in the following
<html>
<head>
<title>Hello</title>
</head>
<body> This is my first homepage.
<b>Hello World!</b>
</body>
</html>
Click on ‘save’ in the file menu
A simple web page
In Firefox
file open file and navigate to desktop select your page
Or else in Internet Explorer
file open file browse and navigate to desktop select
your page
A simple web page
You should see something like this
IS1811
Next week
Working with HTML
Want to read more?
Links and references
http://www.w3schools.com/
http://www.internetworldstats.com/stats.htm
http://www.isoc.org/internet/stats/
http://www.internettrafficreport.com/
http://www.w3schools.com/tcpip/default.asp
http://www.yale.edu/pclt/COMM/TCPIP.HTM
http://cybernetnews.com/