I’m pretty sure we did the tutorials for this lesson yesterday, but had this lecture in the forth week. I swear, they’re all out of whack.

The Internet

Huzages ago, in November 1969 the Internet backbone that we use today was started. At the time it only had four nodes (constrast that with today, we have hundreds of thousands). It was solely used by and for American intelligence, and called ARPAnet, Adanced Research Projects Agency.

As a millitary thing it was a genious idea. Because there were four nodes, it meant that one could come under “attack” (be blown up, or suffer natural disasters) and the other three nodes were still available. This was amazing because back then the only real type of networks were circuit ones (one goes down, they all do).

In 1973 the first node outside of the US was created. Until 1992 the Internet was “owned” by the US government. At that point ISOC was created; a non-profit organisation which intended to look after the Internet by creating standards and making sure it’s available to as many people as possible.

Domains

I disagree with most things that’s said on this slide.

Internet sites need two pieces of information

• domain name from domain name service (DNS) registered by Internet Corporation for Assigned Names and Numbers InterNIC
• IP address, such as 123.123.123.123

–John Cowell

You do not need both of those things. A domain name would be helpful, but you definitely don’t need one unless you’re sharing an IP address. For instance, you can use 64.71.168.124/blog/ to get to one of my other blogs. You can also use the DNS allocated name: www.debiantips.com/blog/

You do need an IP address though – that’s how the internet finds out where you’re looking.

Domains are hierarchical

–John Cowell

That’s incorrect too. My URLs can be formatted however the hell I want. www.dmu.ac.uk is actually on an entirely different server to www.cse.dmu.ac.uk, there’s no hierarchy there. shamess.info and www.shamess.info both get you to the same place, even though that theory would say they aren’t.

He got it wrong about TLDs too; .tv isn’t supposed to be used by TV channels, it’s supposed to be used by people from Tuvalu.

World Wide Web

The World Wide Web is a part of the Internet. It’s not the entire thing. WWW is generally just the area that you get web pages from and such. It’s just a big bunch of files all linked together. Pages being “linked” together is the most important part of the web. Files were much more linear before; just one huge file telling  you all you need to know. Now though there are links within files so you can get to the bit you need quickly.

It’s ‘governed’ by the WWW Consortium. But to be honest, on governed in a way that you’re governed by your grandparents. You know that you should do what they say, but ultimately they can’t make you. They set out guildlines on how best you should present your information on the web; they were the people that formalised HTML and told people what each tag should do. No one appointed them, but they’re still highly respected as an authority.

As I said, the guidelines for XHTML are totally option if you want to follow them or not.  Recent browsers try their best to these days, so you’ll find that Firefox 3.x, Opera 9, and Safari 3 will all look pretty much the same, but Internet Exploder, even the lastest betas still like to go off and do their own thing. That makes it hard for web designers to make their website look the same on all browsers.

Figure 1: A really basic representation of what happens when you click a link

As well as the HTML, your browser receives your browser also receives HTTP headers, which tell it the status of the document you just tried to get (was the download successful? were you forbidden access? does the page exist?), and some other information.

HTML

The server you’re requesting form will send you a tonne of HTML, which your browser renders (processes) and then outputs onto your screen in a much prettier format.

These days if people mention “HTML” they’re probably talking about XHTML, the newer standard which is much more extensible. It’s almost exactly the same as HTML, so if you were taught it in high school or something, upgrading your knowledge shouldn’t be too hard.

I’m not going to be doing a tutorial of HTML here, but I probably will eventually. Until then use Google.

The next set of slides are simply talking about best practises when having a websites, and making sure you’re doing it right. They’re pretty self explanatory.

Other Internet features

This section quickly touches on search engines. The way they work is by having a “spider” which goes to a webpage and then, using pretty complex algorithms, works out what the page is about. It’ll store that data on a huge database. Then it’ll take every link from that first page and follow them, doing the same process to every link it can find.

Of course on the Internet you can get services like e-mail which use different protocols from WWW. SMTP for sending mail, and POP3 and IMAP for receiving.

There’s also FTP, which is a way of talking to a server and managing what files are on there.

It mentions other things and talks about them in more detail.