Transcript BS2911w1

Networking and the Internet (1)
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Where the module fits in:
» Mandatory module for IT and e-Commerce Pathways
» Useful for any business that depends on technology
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Goals of the Module
» Build understanding of Computers and 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
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Hot Issues to be considered
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The Internet and Intranets
» Thin client computing
» e-Commerce
» “Web2”
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Corporate networking
» Inside and between enterprises
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Operating system directions
» Can Linux reduce dependency on Windows?
» Does the mainframe still have a role?
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Future of telephony
» Convergence of voice and data; and cellular with WiFi
» Voice over Internet Protocol (VoIP), Skype, etc.
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Telling significant trends from hype
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It’s not easy:
» People once thought satellite was the way of the future…
» ...and that the Network Computer would challenge Microsoft
(it didn’t, but the idea is being revived as Cloud computing)
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Best approach is to learn the principles
» Basic understanding of how computer works
» Knowledge of Operating System fundamentals
» Key elements of networking technology
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If you look at the underlying problem,
it’s easier to understand the solutions arrived at
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Week 1 Agenda
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What do you know already?
Why does Networking matter?
Some thoughts about e-Business
» Electronic Commerce
» “dot.com” boom and bust in 2000 – and partial recovery
(now it’s just another channel to market for most firms)
» The rest of e-Business
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Hardware foundation – Computer architecture
Software
» Operating Systems
» File storage
» Introduction to Networking
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What is your current experience?
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Know about
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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
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Have already done/got/used
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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?
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Why does Networking matter?
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Because business is about interactions between people:
» Stand-alone computers are only a small part of our world
» Networking is prevalent within companies
» Increasingly used in interactions between companies
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Growth of high-capacity, long-distance networking
» Distance ceasing to be important
(http://www.telecom-tariffs.co.uk )
» Driving globalization of trade
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Networking is an enormous business it its own right
» Multi-billion mergers: Time-Warner/AOL, Skype/eBay
» No sign that growth in traffic will decline…
» …though the profits have largely evaporated
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Business Implications
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Investment: is it safe to invest in networking companies?
» If you get it wrong, you’ll lose your shirt
or miss out on major growth opportunity
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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, HBOS
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Best approach is to:
» Apply normal business principles
» Use understanding of the underlying technology to decide
who to trust
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e-Business
IBM’s term for a business making full use of IT
 Not just e-Commerce – includes any of:
» Electronic support for business processes, for example
– Integrated manufacturing
– Enterprise Resource Planning
– Customer Relationship Management
– Computer-aided telephony
» Communications for:
– Internal activities such as e-mail and information sharing
– Publicity and support
– Supply-chain management
– e-Commerce – B2B and B2C
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Electronic Commerce
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Already a key part of industrial supply-chain
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Orders, bids, payment transferred between partner firms
Allows “Just in Time” logistics
Typically heavily coded information
Use of XML will enable growth of “open” B2B
Retail uses widespread; slightly limited by interfaces:
» Great 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, a killer 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
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Forms of e-Commerce
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B2C – Business to Consumer
» Business operates computer, Customer is human user
» Significant use for business customers – it’s still B2C
» After 10 years growth, user population now extends to many
people in developed world
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B2B – Business to Business
» Heavy use in well-developed niches, usually proprietary
– EDI between companies with permanent relationship,
Previously on private networks, now mainly over Internet
– BACS and other banking systems, including EFT
» Open B2B, without need for proprietary network or software
– Relatively small coverage so far – most so-called B2B
actually has a human user at the customer end
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Growth Implications
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B2C
» Most G7 households now able to purchase on-line
» Actual purchases low relative to customers’ total spending
» Think of the concurrent users you’d get if they all piled on!
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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
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Server reliability & scalability is going to be a key factor
» Tilting balance from Windows to Solaris and z/OS
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“Legacy” Applications
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Most of world’s money transactions go via CICS/390
» 30B transactions/day from 30M users – $300B/week
» 5000 packages from 2000 vendors, plus bespoke
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applications developed over 30 years
figures
» 950K programmers earn living from CICS
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Most CICS applications are 3270 terminal based –
how do they play on the Internet?
z/OS and CICS contain Web-server functionality
» Easy to web-enable old and new applications
» Underlying code remains unchanged (often COBOL)
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z-Series scales from desk-side processor to parallel
sysplex able to handle >250,000 concurrent users
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Other e-Business considerations
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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
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Effect on economic balance of power
» Large companies will need huge database processing
» Can then get strong control on suppliers, and
understanding 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?
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Any Computers Here?
DVD recorder
makes and
plays DVDs,
with a fixed
user interface
When this hard-disk
recorder downloads
new software, its
user interface can
change
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DVD player with
fixed user interface
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What is a Computer?
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Full of electronics?
» But that’s true of a radio or television or video recorder
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Does complex things?
» Like a C17 musical clock or an automaton
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Does calculations?
» But a pocket calculator does that
» And the WW2 code-cracking machines at Bletchley Park did
whole streams of calculations using electronics
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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)
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Key features of a Computer
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Computers are programmable
» They contain memory into which you can load instructions
which they execute one after another
» Change the contents of memory, you change what they do
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Program can interact with the world, and take different
actions depending on what happens
» For example, cell-phone measures strength of signal, and
hunts for a new cell when it gets weak
» Windows reacts to mouse-clicks and keyboard actions
» We call its interactions “inputs” and “outputs”
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Computer invented in 1935; nobody built one until 1948
» That’s when the first memory technology arrived
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Modern Computers
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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
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Contain electronic memory to hold programs and data
» These chips are much more repetitive than microprocessors
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Have some mechanism for saving data from memory
and getting it back (such as disk drives, SIM cards)
Interact with the world through input and output devices
(sometimes called peripherals)
Also contain interrupt hardware to handle asynchronous
events from outside (or inside)
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Foundation for Networking
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You have an understanding of basic computer
architecture and networking from last year
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We need to build on this in several ways:
» pursue the idea of “encapsulation” of function into operating
systems
» Plus how to do things concurrently
» understand the factors that determine performance
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First let’s revise basic hardware design
» Some of this should be familiar from 14 months ago
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Computer Architecture
Memory
Processor
1234567890-=
QWERTYUIOP[]#
ASDFGHJKL;’
ZXCVBNM,./
Input
(Data)
Output
(Information)
Bus
Disk Storage
Other
long-term
Storage
Processor executes instructions from memory,
 and works on data in memory
 Other data flows through the bus
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Storage Hierarchy
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Cache on processor chip
» Very fast indeed, very expensive, rarely over 2MB
» Allows actions to take place entirely on the chip
» http://www.extremetech.com/article2/0,1697,1155325,00.asp
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2nd-level cache
» Very fast, less expensive, typically 2MB
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Main memory
» Fast: quoted speed <30nsec
» Price down from £25/MB in 1996 to under 2p now
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Magnetic Disk: non-volatile (unlike main memory)
» Slower: 10msec access, longer if heads must move
» Large and cheap; e.g. 750GB disk now under £50
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sec msec µsec nsec
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Operating Systems
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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
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Modern operating systems make it look as if the
computer is doing several things at the same time
» Our operating system is Windows XP –
how many of you are now on Vista (bad luck) or W7?
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Concurrent Operations
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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.
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We say the machine is doing things “concurrently” –
they’re 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
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Typical File Storage
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PC disks are organized into “allocation units”
» Identical blocks, addressed by number
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Some of these are used to hold the actual data
The others contain pointers to the data, and names so
you can refer to it – these are directories to the files
A “folder” is a piece of data consisting of a directory,
so you can build a hierarchy in the file system
Most modern computer systems work in this way,
including: DOS, Windows XP, NT, OS/2, Unix, VMS, VM
DOS file identifier are made up of two pieces:
» a name of up to 8 characters, such as fred0516
» a type (or extension) of up to 3 characters, such as doc
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Files in Windows
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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 & later, by Registry entries
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For any file type, you can define “methods” (operations)
» Most have an Open method (usual default for double-click,
though not for Word templates)
» Other methods accessible by right-clicking the file ID
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Files can now have “long names” – longer than 8+3
» Stored in a separate place in the directory
» 8+3 name generated to go in the “old” file ID position
» You may sometimes see the 8+3 name on a diskette
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Directory structure on Windows
Root Directory
C:\
My letters
c:\mylets\
This year
c:\mylets\2010\
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My programs
c:\myprogs\
Archives
c:\mylets\oldies\
Windows
c:\windows\
System files
c:\windows\system\
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