1. MWD1001 – Website Production Web Browsers Week 11

2. MWD1001 – Website Production Who cares about browsers?  Most people use Internet Explorer  Tech savvy use Firefox  A few people use Opera  It doesn’t really matter any more!

3. MWD1001 – Website Production Straw poll  IE6:  IE7:  Firefox:  Opera:  Other:

4. MWD1001 – Website Production Main Browser Families

5. MWD1001 – Website Production Microsoft Internet Explorer (IE)  Multiple versions in regular use –Currently transitioning from 6 to 7  Tight integration with Windows operating system  Dominant browser for corporate and home users  Trident rendering engine used by Outlook Express, winamp, AOL browser

6. MWD1001 – Website Production Gecko  The rendering technology behind Firefox, Flock, Camino, Seamonkey, …  Open source technology  Cross-platform, runs on Windows, Mac, Linux/Unix

7. MWD1001 – Website Production Opera  Innovative web browser  Low market share compared to big two on the desktop  Very well represented in smartphones and mobile apps  Presto rendering engine

8. MWD1001 – Website Production Safari/Konqueror  Safari is the browser Apple ship on all Macs, now on Windows and iPhone  Konqueror runs on Linux as part of the KDE environment  Both derived from Webkit engine  Said to be very standards compliant

9. MWD1001 – Website Production Brand New – Chrome  Google launched their own browser last month  Based on Webkit engine  Optimised for JavaScript and web apps  PC only right now

10. MWD1001 – Website Production Market Share Source: w3schools.com Oct 2008

11. MWD1001 – Website Production Why does it matter

12. MWD1001 – Website Production W3C Standards  World Wide Web Consortium sets standards for HTML, CSS  Can browsers pass the ACID Test?ACID Test  Internet Explorer used to be the de facto standard when it had > 90% market share  No current browser fully conforms to all current standards  Cannot rely on features to be present –Always aim to degrade gracefully

13. MWD1001 – Website Production ActiveX  IE supports ActiveX controls on Windows –Can be used to implement Client-side code –Not cross-platform –Associated with security risks  Most browser support Flash as an alternative  Advanced JavaScript (AJAX) code can be implemented client-side

14. MWD1001 – Website Production Authentication  Browsers and web servers support different authentication schemes  Apache offers Basic and Digest Authentication  IIS offers Basic, Cookie and NTLM  NTLM only available in IE on Windows /adamisherwood /authentication

15. MWD1001 – Website Production What is NTLM  NTLM passes the user’s Windows login credentials to the server  Using IE, users are not challenged for login at all if their acct is authorised  Useful in a corporate environment where browsers and user accounts are controlled

16. MWD1001 – Website Production JavaScript and DOM  Since its introduction JavaScript has had compatibility issues  Often through competition by features  Events are not supported by all browsers –E.g IE allows onClick on Image tags, Netscape didn’t  CSS Properties such as position: float; not in IE6

17. MWD1001 – Website Production JavaScript and AJAX  Writing code is harder than it needs to be  Have to anticipate compatibility issues  Need to write more than one version of code

18. MWD1001 – Website Production How can you tell?

19. MWD1001 – Website Production Server-side  User-agent string passed to server as HTTP environment variable  User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4  May be spoofed –Useful if you maintain different versions –Important to check for authentication

20. MWD1001 – Website Production Client Side  Much more important for client-side programming  If you rely on a feature which turns out to be missing your app fails  JavaScript methods exist to check for IE or NS versions –May be spoofed  Better to use the black art of browser sniffing

21. MWD1001 – Website Production Browser Sniffing  Don’t actually care which browser!  Need to know whether function supported  IE has a document.all array containing all page elements  if (document.all) { //some IE specific code }  More advanced code relies on getElementById() function /adamisherwood /sniffing

22. MWD1001 – Website Production Summary  Browser market fragmented  Functionality and capability varies  Cannot rely on standards  Fail Gracefully