Web Development From the Ground Up, a Series for Novice Computer Users Lecturer: Philip Matuskiewicz Thursday: October 15, 2009 Email: [email_address] or [email_address] Lecture Website (created during 1 st lecture): http://famousphil.com/09web
Browsers speak HTTP (HyperText Transfer Protocol) which is the language that web servers speak
A web server will return a file with text in it (among other types of files; eg. Image files)
The main file returned is plain text and is written in HTML(HyperText Markup Language) which is the standard that all browsers should be able to understand
All files have extensions…
common extensions for HTML are .html, and .htm.
If the server is modifying the html of a page prior to sending it to the browser, the extension may be .php for PHP, .cgi for CGI, and .asp for ASP (these will be discussed in later lectures)
How does the browser communicate with the server?
The internet is a huge computer network that stretches world wide
When your browser requests a page, it uses the internet to find then connect to the server responsible for that page
This is basically done through a combination of DNS (Domain Name Service) lookups and routers that connect every computer together some way.
These can be compared to how the post office routes your mail through its system, they generally look at the to address and route your mail towards the large sorting facility which knows more about your location. Once it figures out what the sorting destination is (DNS), it will route the message there via planes and trucks (routers).
All too often, when developing websites, all browsers will show your webpage differently. This is because they follow the same specifications but interpret them differently, or they may not follow the specifications at all.
Internet Explorers 6/7 are a huge problem because they didn’t really follow the specifications. IE 8 has gotten a lot better! This is why on the IEEE website, I have separate code for CSS in IE vs Firefox and other browsers.
Chrome follows the standards almost exactly as does Internet Explorer 8 (Thank you Microsoft!). This is why sites may look fine in Firefox (which sometimes will loosely follow the standards and fill in the gaps) where IE8 / Chrome will make your page look ugly.
Before standards were widely followed, browsers were really good at detecting errors and figuring out what they meant. This is why poorly coded WebPages still would look fine to all browsers that they were tested in.