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Protecting Against Failure. Backups – multiple generations Surge Protector – power surges UPS – uninterrupted power supply Mirroring data / RAID. People are Risky. don’t see themselves as a risk. work around security. Reliability.
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Protecting Against Failure • Backups – multiple generations • Surge Protector – power surges • UPS – uninterrupted power supply • Mirroring data / RAID
People are Risky • don’t see themselves as a risk. • work around security.
Reliability • when we rely on computers, and something goes wrong, the impact can be significant : • Therac 25 • Y2K – $100 billion • cannot find all of the bugs • they harder bugs are to find, the worse they are may be. • increased complexity compounds the problem.
Security vs. Privacy • balancing. • examples : • e-mail at work • cell phone with GPS • active badge
Internet & Web • the World Wide Web and the Internet are not the same thing. • WWW – an application of the Internet. • Popularity : • easy to use. • easy to add • easy to search.
Internet Applications • email & mailing lists • FTP & file sharing • Usenet & boards & forums • World Wide Web • Instant Messaging & Chat • Remote Login & Telnet • VOIP
Web • distributed information system. • hypertext & hypermedia. • browser : software for accessing www. • Plug-in : extend the capabilities of your web browser.
Hypertext & Hypermedia • documents linked in non-linear ways • web is only one example (help files, DVDs, multimedia applications)
Hypertext & Hypermedia • may not have the links you want • dead links – maintenance • not like hardcopy – notes and highlighting • hard to read long passages of text on the computer screen • disorienting
Web • url : uniform resource locator • http : hypertext transfer protocol • html : hypertext markup language • web authoring tools • Domain name registry
<html> <head> <title>Web Example</title> </head> <body> <h1>CSCI 1200</h1> <p> CSCI 1200 is a computer science class offered for non-majors. </p> </body> </html>
Tags • anchor tag <a href="url">Text to be displayed</a> • image tag <img src = “happy.gif“>