IMS5401 Web-based Systems Development
Semester 1, 2005
Tutorial 2: Using the Internet and the Web
Purpose
This tutorial aims to help you to understand the two network elements of the web – the Internet and hypertext document linking, and think about their implications for web usability for different purposes:
· The lab section of the tute aims to make sure you understand the basic technology of the Internet - which provides the means by which computers are connected, and the web - which provides the means by which documents stored on the Internet are linked.
· The discussion section aims to encourage you to start to identify the strengths and weaknesses of the network aspects of the web, and think about how they affect its usability for different purposes/applications. This will be a key theme of your first assignment.
A. Discussion
The web has two network elements, the Internet and hypertext document linking. The Internet enables computers to connect and transmit information to one another. The hypertext web enables links to be established between documents stored on computers on the Internet.
This week’s lecture examines a number of features of the Internet as a network of computers and the web as a network of documents. These features are important factors in determining the strengths and weaknesses of web, and therefore in determining what sorts of things the web can be used for.
In last week’s class you identified some of the applications for which you find the web is useful and some where it is not. The main point of this week’s discussion is to analyse the extent to which the use of the web for these purposes is made easy (or difficult) by the network features of the web. It is important that you be able to do this, because in your first assignment you will be asked to assess the importance of network connectivity for a particular web application, and discuss its strengths and weaknesses.
With this in mind, your tutor will ask you to choose a web application, and consider and discuss some or all of the following:
1. To what extent is the usefulness/usability of this application affected by:
· the network capabilities of the Internet?
· the document linking capabilities of the web?
Identify the main network/linking features which enhance or limit the usability of the application.
2. What sort of enhancements are needed to the networking characteristics of the web to make this application more useful/usable? eg speed, accessibility, access devices, etc.
3. Does the web have network features and/or document linking features which enable abuses/mis-uses which make this application less usable/useful?
4. It is interesting to make the comparison between the web and other traditional methods for doing this application. To what extent does the networking/document linking capabilities of the web offer significant advantages or disadvantages to these traditional methods?
5. What might the future hold? Try to think ahead 5-10 years; how might the web’s network capabilities change (for better or worse) to affect this application?
6. Read Geoff Huston's article, 'The Trashing of the Commons' which I have placed in the resources section of the web site. It raises the question as to whether the strengths of the Internet which have helped the Web grow will prove to be its downfall, because they are so open to abuse. Do you think that will apply for this application? What will have to happen to prevent these problems?
B. Lab-based (self-paced)
1. General structure of the Internet and the web
A web site which I will use for several tute exercises is called www.howstuffworks.com. It is a sort of on-line encyclopedia, but with very detailed descriptions written for intelligent beginners. It has some good entries explaining the basics of how the Internet and the Web work. Go to the Internet section which is under the Computer section, and try the articles on How Internet Infrastructure Works, and How Web Servers Work. There is also a short one on What is a Packet, which you might find useful.
2. The Domain Names System (DNS)
(i) While you are at How Stuff Works, try its section on How DNS Works. For other descriptions of the DNS, try http://www.dns.net/dnsrd/docs/whatis.html. It gives several links to articles which explain how the DNS works. In particular the article on domains by Mark Horton gives a simple detailed explanation of naming systems.
(ii) Test out the DNS system for yourself by typing in some invalid web site references, and note how the DNS system tells you when it can’t find the server you have asked for (like a “this address not known; return to sender” letter).
3. Getting a web address
(i) Go to www.icann.org. This is the American (effectively international) body responsible for domain names world-wide. The site tells you a bit about domain names and how they are managed around the world; you can find out who has been delegated to look after domain names in different countries. Similar information is available from www.internic.net, which is a general public information resource for domain names and registration.
(ii) Go to http://www.melbourneIT.com.au This is one of the Australian companies which has the rights to register domain names. At this site you can buy and register a domain name with a .com.au, .net.au or .org.au address. You can also check to see whether a given domain name of that type has already been bought by someone else.
(iii) Go to http://www.anu.edu.au/people/Roger.Clarke/II/OzI04.html. This is an article which tracks the evolution of the Internet and domain names in Australia. It is very interesting reading if you are really interested in Australian Internet history, and it gives a good idea of how messy the story of controlling the net has been in this country (and probably most other countries could tell similar stories!).
4. Using the Internet/Web
(i) The Internet Society runs a very useful web site which has lots of general information and statistics about the internet and the Web plus links to other useful sites. For example, it has a connection to the Internet Traffic Report, which is an on-line guide to the state of the traffic on the Internet - like a traffic report on the state of congestion on the road system. Go to www.internettrafficreport.com/main.htm It maintains a constant watch over traffic throughout the world and shows what state the network is in.
(ii) It also has a link to a regular review of the number of Internet domain names held in the DNS. Go to www.isc.org/ds/ There you can look at the results of their regular surveys of web domain names and see the trends in web domain growth.
5. More advanced stuff
The technology behind the internet is very complex, and technical people spend a lot of time arguing over how TCP/IP and http should really work. TCP/IP is a very complex protocol and http is very simple. For some simple technical insights into the Internet technologies, try http://www.anu.edu.au/people/Roger.Clarke/II/IPrimer.html. It is a bit old, but not bad. I will put some more complex stuff in the resources page for anyone who is interested.