Networking and the Internet 1

1
Networking and the Internet (1)

• Where the module fits in
• Mandatory module for IT and e-Commerce Pathways
• Useful for any business that depends on
  technology
• Goals of the Module
• Build understanding of Computer Networks
• Prepare you to make decisions with IT
  implications
• e-Commerce, internal networking
• Judgement is improved by understanding the issues
• Enable understanding of Computer press
• So that you can stay current in fast-moving area
• Build practical skills with HTML and the Web

2
Telling significant trends from hype

• Its not easy
• People once thought satellite was the way of the
  future
• ...and that the Network Computer would challenge
  Microsoft
• Best approach is to learn the principles
• Basic understanding of how computer works
• Knowledge of Operating System fundamentals
• Key elements of networking technology
• If you look at the underlying problem, its
  easier to understand the solutions arrived at

3
What is your current experience?

• Know about
• Creating web sites
• ADSL
• Indirect telephone services
• Internals of computer
• Local Area Networks (LAN)
• Instant Messaging
• Streaming audio and video
• Voice over the Internet
• B2C e-commerce
• Internet banking
• Data Encryption
• Wireless technologies
• Cellular technologies

• Have already done/got/used
• Web site creation
• ADSL
• VarTec, OneTel etc.
• Computer upgrade
• LAN Set up
• MSN Messaging or equivalent
• Internet radio or video
• Conversation over Internet
• Bought things on-line
• Internet banking
• Set up 128-bit encryption
• WiFi or other wireless LAN
• Data/photo over mobile phone

What else do we need to cover?
4
Business Implications

• Investment is it safe to invest in networking
  companies?
• If you get it wrong, youll lose your shirt or
  miss out on major growth opportunity
• In your own enterprise, should you stick to
  vendors so big they are likely to survive?
• Or prefer the more innovative and fleet of foot?
• In any case, does big mean safe? Think of Enron,
  Maxwell
• Best approach is to
• Apply normal business principles
• Use understanding of the underlying technology to
  decide who to trust

5
Electronic Commerce

• Already key part of industrial supply-chain
• Orders, bids, payment transferred between partner
  firms
• Typically heavily coded information
• Use of XML will enable growth of open B2B
• Retail uses are limited by interfaces
• OK for commodities, where buying determined by
  price
• Lack of look and feel limits range of goods
• Attempts to provide more attractive images can
  lead to intolerable response times on dial-up
• Key issue is mapping customers paradigms to
  web-site
• Must merge business data with web content to have
  any chance of meeting user expectations

6
Growth Implications

• B2C
• Huge population now able to purchase on-line
• Actual purchases low relative to customers total
  spending
• Think of the concurrent users youd get if they
  all piled on!
• B2B
• Open B2B development is very patchy
• Transaction rate is not constrained by human
  think time
• Only constraints are speed of partner computer
  and Internet connections
• Server reliability scalability is going to be a
  key factor
• Tilting balance from Windows to Solaris and z/OS

7
Other e-Business considerations

• Not just a matter of electronic sales and
  purchases
• How do you milk the data you get?
• Enterprise Resource Planning Integration of
  production and inputs with sales
• Customer relationship management (see BS3917)
• Marketing information and exploiting it
• Effect on economic balance of power
• Large companies will need huge database
  processing
• Can then get strong control on suppliers,
  andunderstanding of existing customer base
• Smaller enterprises can still join relatively
  cheaply to exploit new markets missed by big
  boys
• But cost of entry to e-commerce has been growing
  why?

8
What is a Computer?

• Full of electronics?
• But thats true of a radio or television or video
  recorder
• Does complex things?
• Like a C17 musical clock or an automaton
• Does calculations?
• But a pocket calculator does that
• And the WW2 code-cracking machines did whole
  streams of calculations using electronics
• All those devices do exactly what they were built
  to do
• Their capabilities are wired in, so if you want
  to do something different, you need to tell them
  to (calculator)
• or rebuild the device to do a different sequence
  of things (Bletchley Park code machines)

9
Modern Computers

• Contain microprocessors chips containing
  circuits for calculations and for handling data
• Now several million transistors etched on the
  chip
• Some of them function as a clock to organize
  operations
• Contain electronic memory to hold programs and
  data
• These chips are much more repetitive than
  microprocessors
• Have some mechanism for saving data from memory
  and getting it back (such as disk drives, SIM
  cards)
• Interact with the world with input and output
  devices (or peripherals)
• Also contain interrupt hardware to handle
  asynchronous events from outside (or inside)

10
Computer Architecture
Processor
Memory
1234567890- QWERTYUIOP ASDFGHJKL ZXCVBNM,./
Output (Information)
Input (Data)
Bus
Other long-term Storage
Disk Storage

• Processor executes instructions from memory,
• and works on data in memory
• Other data flows through the bus

11
Storage Hierarchy

• Cache on processor chip
• Very fast indeed, very expensive, rarely over
  32KB
• Allows actions to take place entirely on the chip
• 2nd-level cache
• Very fast, less expensive, typically 256KB -
  512KB
• Main memory
• Fast quoted speed lt30nsec
• Price down from 25/MB in 1996 to 7p now
• Magnetic Disk non-volatile (unlike main memory)
• Slower 10msec access, longer if heads must move
• Large and cheap e.g. 160GB disk now just over 50

sec msec µsec nsec
12
Operating Systems

• Though the processor is simple and serial, we
  want to do more complex things, often several at
  once
• An operating system is a program that provides
  the building blocks of complex systems
• Some simply encapsulate function to save every
  application from having to include a copy
• Others handle specific hardware, presenting a
  generic interface that hides behaviour unique to
  that hardware
• Sometimes the interface is so generic that it has
  little to do with the hardware file structures
  are the best example
• Modern operating systems make it look as if the
  computer is doing several things at the same time
• Our operating system is Windows XP

13
Concurrent Operations

• To give the appearance of doing several things at
  once
• OS must stay ready to accept work
• keystrokes, mouse clicks, signals from modem,
  printer ready to receive another buffer of data
• These can interrupt a computation already being
  run
• It then does a bit of the required work,
• then goes back to an interrupted task, and so on.
• We say the machine is doing things concurrently
  theyre not simultaneous, but they look it!
• The key is switching the CPU between logical
  processes
• In theory, you could go round polling high
  overhead
• In practice, concurrency depends on hardware
  interrupts

14
Files in Windows

• Windows uses the file type to give short cuts to
  processing the file
• In Windows 3.x, done by an association in
  WIN.INI
• In Windows 9x, NT, 2000 XP, by Registry entries
• For any file type, you can define methods
  (operations)
• Most have an Open method (default for
  double-click)
• Other methods accessible by right-clicking the
  file ID
• Files can also have long names longer than
  83
• Stored in a separate place in the directory
• 83 name generated to go in the old file ID
  position
• You may sometimes see the 83 name on a diskette

15
Computer Processor Machine code
Clock
Arithmetic and Logic Unit
Central Processor Unit
1 Load 2 Store 3 Add 4 Subtract 5
Multiply
Memory 310 1 1 600 314 1 2 602 318 5 1 2 31A 2 1
604
...
16
Networking and Communications

• An area made confusing by range of different
  activities that fit under this heading
• Electrical (or equivalent) signals actually
  transmitted(down twisted-pair, coaxial cable, or
  by radio)
• How the transmission medium is managed(modem,
  network card, hub)
• How we address data to make sure it gets to
  destination
• How we code the information so receiver
  understands it
• How we package information to send it to other
  application(email, screen-shots, file transfer)
• Can resolve confusion by the concept of layers
• Convention is to show electrical signals at bottom