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IT – som værktøj

IT – som værktøj. Bent Thomsen Institut for Datalogi Aalborg Universitet. Opgaver og øvelser fra sidst. Web search Instant messaging Unix – X-win32 version 5.2.2 LaTeX – brug Unix maskinen dolomit. Introduction to Networks and the Internet. Bent Thomsen Institut for Datalogi

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IT – som værktøj

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  1. IT – som værktøj Bent Thomsen Institut for Datalogi Aalborg Universitet

  2. Opgaver og øvelser fra sidst • Web search • Instant messaging • Unix – X-win32 version 5.2.2 • LaTeX – brug Unix maskinen dolomit Bent Thomsen - FIT 1-1

  3. Introduction to Networksand the Internet Bent Thomsen Institut for Datalogi Aalborg Universitet

  4. What is a network • Carrier of data between connected computers • What does a network consist of? • End hosts connected to the network • Physical links that carry data • Ethernet, FDDI, ATM, … • Routers/switches • Protocols • TCP/IP, HTTP, FTP, SMTP, … • Applications that communicate with each other • Printing, email, file transfer, web browsers, .. Bent Thomsen - FIT 1-1

  5. Small Local Networks Bent Thomsen - FIT 1-1

  6. Local Area Networks Bent Thomsen - FIT 1-1

  7. Large Local Area Networks Bent Thomsen - FIT 1-1

  8. Client/Server networking • Access large data sets and huge computing resources from desktop machines • Separate data processing from presentation • Facilitate several views on raw data • Split workload between machines across a network • Do some processing locally and some on a server • Middleware and distributed objects Bent Thomsen - FIT 1-1

  9. Direct connection Bent Thomsen - FIT 1-1

  10. Client/Server connection Bent Thomsen - FIT 1-1

  11. Web based client/server Bent Thomsen - FIT 1-1

  12. The Internet • A set of connected networks • All use the same network protocol (IP) • Most common protocol used is TCP/IP • Connection oriented • Reliable, in-order byte-stream • Application protocols on top of TCP/IP • SMTP • HTTP • FTP • UDP is another protocol • Used for streaming video and audio • Some peer-to-peer applications Protocols define format, order of messages and actions taken on messages Bent Thomsen - FIT 1-1

  13. The Internet is a collection of interconnected networks Bent Thomsen - FIT 1-1

  14. Connecting to the Internet • Through ISP • Modem dialup • Always-on: ADSL, Cable, FWA • Direct/Dedicated network • Companies • Universities • (WLAN operators) Bent Thomsen - FIT 1-1

  15. How to connect to the Internet Bent Thomsen - FIT 1-1

  16. An Internet Backbone Bent Thomsen - FIT 1-1

  17. A bigger Internet backbone UUNet/WorldCom Bent Thomsen - FIT 1-1

  18. Some Internet basics • Each computer on the internet has a unique address – the IP address • 123.225.409.109 • Most end-user computers are allocated an IP address when they connect – DHCP • IP addresses can be given a name • E.g www.but.auc.dk • Looked up via DNS (130.225.56.21) Bent Thomsen - FIT 1-1

  19. Package switched Bent Thomsen - FIT 1-1

  20. Routing on the Internet Bent Thomsen - FIT 1-1

  21. Things that may be in your way • Operating system settings • Gateways • Firewalls • Proxy servers • Caches • Virus filters • Spam filters • Adult filters Bent Thomsen - FIT 1-1

  22. Internet Applications • Electronic mail (email) • Mailing lists • Newsgroups • File Transfer • Chat • Instant Messaging • World Wide Web Bent Thomsen - FIT 1-1

  23. The World Wide Web • 1991 The web (HTML/HTTP) - 1 web server • 1993 The Mosaic Browser - 186 web servers • 1994 Netscape – over 42000 web servers • 1995 Internet Explorer - over 200000 web servers • 1995 Java • 1996 Browser wars – over 1 million web servers • 1997 IE4 • 1998 XML and WAP – over 5 million web servers • 1999 IE5 Bent Thomsen - FIT 1-1

  24. Cyberspace “a consensual hallucination experienced daily by billions of operators in every nation …” Gibson Bent Thomsen - FIT 1-1

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