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ClientServer Architecture

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Client/Server Architecture. Client/Server is advanced form of Distributed ... Dell, Gateway, HP, Sony, Toshiba, IBM. BestBuy, CompUSA, CircuitCity ... – PowerPoint PPT presentation

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Title: ClientServer Architecture


1
Client/Server Architecture
  • Client/Server is advanced form of Distributed
  • It is a way of looking at infrastructure
  • let the best processor do the job
  • PCs excel at ...
  • Host systems excel at …
  • So take an activity and let them share it
  • Database Server
  • PC makes query, server retrieves data
  • Mail Server
  • PC creates mail, mail server routs it
  • Web Server
  • Server has web page, PC displays it

2
2-Tier vs. 3 Tier Architecture
  • Client-Server is 2 tier
  • Applications are split up
  • part of software on client
  • part of software on server
  • Database is on server
  • Problems
  • when client s/w is updated
  • as volume grows
  • 3 Tier Architecture
  • Separate platforms for three different functions
  • input, process and storage

3
Three-Tier (or n-tier) architecture
  • Front-End (Input - what users see)
  • PCs or Thin Clients w/ GUI
  • Windows or Web-based Interface
  • Give access to middle tier, display what middle
    tier says
  • Middle Tier (Processing)
  • Application/transaction server(s)
  • Does authentication processing
  • Back-End (Storage)
  • Database server(s) SANs
  • Other possible layers
  • Legacy System(s) - old centralized apps
  • Load balancers

4
E-Commerce Models (pure plays)
  • Pure-play vs. Clicks-and-Mortar
  • Virtual Storefront pseudo store
  • Online Marketplace or Electronic Broker
  • Where buyers and sellers meet, auctions
  • Information Broker
  • Provides/sells info on firms, revenue from firms
  • Transaction Broker
  • Process online sales for other firms (fee based)
  • Content Provider (syndicator)
  • Packages news, music… over the web
  • Online Service Provider
  • Access to internet portal to other services
  • May sell member info
  • Virtual Community
  • Hosts chats, bulletin boards, etc.

5
IT Fundamentals
  • 1. Total Cost of Ownership
  • 2. How Computers Work
  • 3. Organizational Computing
  • 4. Storage
  • 5. Input/Output
  • 6. Buying a Desktop Tutorial

6
Total Cost of Ownership
  • Hardware Acquisition - purchase price
  • Software Acquisition - license or s/w
  • Installation
  • Training
  • Support
  • Maintenance - cost to upgrade, repair
  • Infrastructure - link to nets, storage
  • Downtime - lost productivity
  • Space and Energy - utilities, facilities

7
TCO Takehome Project
  • Research a Basic Unit and some upgrades (see next
    slide)
  • Online from 2 sources
  • Dell, Gateway, HP, Sony, Toshiba, IBM
  • BestBuy, CompUSA, CircuitCity
  • Find 2 systems that meet the specs (next slide)
  • From different manufacturers
  • Determine the cost of basic unit
  • Determine cost if upgraded RAM, Hard Drive
    Monitor
  • Identify the warranty and extensions
  • Identify the service options and cost
  • Determine total cost of ownership per PC
  • (see other slide)
  • Give me a memo describing systems and your
    recommendation - which computer and why

8
Basic Unit and Upgrades
  • Basic Unit (Desktop)
  • CPU - 2 gigahertz
  • Hard Drive - 40 gigabytes
  • RAM - 256 megabytes
  • Portable storage - CD-R/RW DVD player
  • Monitor - 17 inch CRT
  • Upgrades
  • CPU - 3 gigahertz
  • RAM - 512 megabytes
  • CD-R/RW DVD-R/RW
  • Monitor - 17 inch flat screen (not flat panel)

9
Other TCO issues
  • We will want 30 units 2 backups
  • 5 units need on-site service, the others will be
    shipped for repair
  • Should either come with XP pro or we will want to
    add it (use their price)
  • We have MS Office licenses (65/PC)
  • We have other licenses (150/PC)
  • A part-time support person will be hired
    (10,000/yr, no benefits)

10
Data Representation Vol/Speed
  • Computer devices are built using switches
  • Switches have two possible states - ON or OFF
  • Inside the computer
  • circuit open 0 or OFF, circuit closed 1 or ON
  • direction of current - one way is OFF, other is
    ON
  • Each switch is a BIT - value of a bit is 1 or 0
  • When you press a key on the keyboard…
  • a set of 0s and 1s are sent to CPU (ASCII code)
  • ex 10011001 Y
  • each character on keyboard 1 byte (8 bit code)
  • 1Gbyte more than a billion characters
  • Speed of Computer
  • Hertz how fast things move (ex MegaHrtz)
  • IPS (instructions per second, MIPS) how much
    can do
  • FLOPS (floating pt ops) calcs w/ decimal pts.

11
What a CPU Does
Memory
12
What a CPU Does
Data Bus
Memory
External Bus or I/O Bus or Local/Expansion Bus
Internal Bus
13
Typical Steps
  • What happens when you double-click on WP?
  • What happens as you type your report?
  • What happens when you save your report?
  • What happens when you turn off PC?
  • What happens when you open the file again?

14
What a CPU Does
Memory
disk cache
CPU
external cache
internal cache
DMA hard drive
disk controller
Sound card Video card
15
Computer Platforms
  • High End
  • Supercomputers (cutting edge)
  • Parallel computing or super-cooled
  • Used in labs or high-end networking
  • Mainframe (business workhorse)
  • Massive memory/processing
  • Mid-range
  • Super-minis
  • Midrange server (dept wrkhorse)
  • Network Server (souped up PC for Lan)
  • Low-end
  • Workstation
  • Desktop
  • Handhelds

16
Parallel Processing
  • Slave Processors
  • add-on processors are not really parallel, CPU
    still in control
  • Fault Tolerant Processors
  • where multiple processors mirror each other
  • same transaction processed multiple times
  • True Parallel Processors
  • multiple CPUs
  • either share memory
  • or are virtual machines

17
Primary Storage (fast to slow)
  • Internal Cache Memory (L1 - inside CPU chip)
  • very fast volatile memory
  • stockpile data/instructions CPU uses next
  • External Cache Memory (L2 - outside CPU)
  • fast volatile memory
  • stockpile data/instructions for intl cache
  • RAM - Random Access Memory
  • volatile memory
  • holds what might be needed by CPU
  • generally expandable
  • Triple cache (L1/L2 in CPU, L3 outside)

18
Secondary Storage Concepts
  • Memory vs Secondary Storage
  • Memory primary or working storage
  • Writing vs. reading (output vs. input)
  • Removable vs. non-removable
  • whether medium is portable
  • Media (disk) vs. Drive
  • Media is the thing that is read
  • Drive does locating(access)/reading/writing
  • it also includes the drive controller (processor)
  • Backup
  • making a copy in case of disaster
  • Archiving
  • Older records stored on slower media

19
Secondary Storage Features
  • No matter what technology used, there are
    features that never change
  • Format - sequential/direct
  • Capacity (volume of storage)
  • Size (of device/media)
  • Access time - how fast can locate
  • Read time - how quickly read
  • Ability to write/rewrite ( speed)
  • Portability of device/media
  • Fragility
  • Longevity
  • Cost of device/media

20
Magnetic Storage Devices
  • Floppy Disks (thin plastic iron oxide)
  • slow speed, low capacity
  • Zip Disk/EZFlyer
  • cassette larger than floppy, 250mb
  • Hard Disk (thick platter rust)
  • vacuum sealed, high volume, non-removable
  • one platter or multiple platters stacked
  • Removable hard disks
  • Jaz/Orb (portable media)
  • semi-portable (swappable but fragile)
  • Tape Drives Tape media
  • large reels, smaller cartridges

21
Optical Storage
  • Laser beams read/write to plastic disk
  • create pits to represent 1 or on
  • higher capacity than magnetic
  • Compact Disc Standard
  • CD-ROM - read only
  • CD-R - Write Once, Read Many
  • CD-RW - erasable
  • phase change - heat plastic, removes pits
  • DVD - film industry standard
  • DVD-ROM, DVD-RAM
  • High capacity, two-sided

22
Memory Tech as Sec Storage
  • EEPROM
  • Electronically Erasable Programmable Memory
  • Originally developed to control machines in
    factories
  • Today use for secondary storage
  • Flash drives
  • Memory Sticks
  • Memory cards
  • Inside IPODs, MP3 players

23
Storage in Organizations
  • Mass Storage Subsystems
  • Racks of
  • Large capacity tape cassettes
  • Large capacity diskettes in sealed cases
  • Robotic Arm that finds them
  • CD Jukeboxes or Magazines
  • RAID - Redundant Arrays of Inexpensive Discs

24
Enterprise Storage Architectures
  • Local Storage
  • Each server is connected to its own RAID
  • Network Attached Storage
  • RAID is attached to network so all servers can
    use it
  • typically NAS work at the file level
  • easy way to deal with growing storage needs
  • good when a lot of devices need common files
  • Storage Area Network
  • Create a separate network of RAID devices that
    can communicate with your server network
    (subnetwork)
  • good way to ease the load on your primary network
  • typically SAN work at the sub-file level
  • better for e-commerce (transaction data)
  • Web Storage you use web to store stuff on
    vendor multiuser machine (server)

25
Storage Issues
  • Everyday storage
  • Pick storage that fits
  • Security policies
  • Backup issues
  • What technology
  • Backup policies
  • When - how often
  • What - which data?
  • Where - how many media, reuse
  • Archiving issues
  • Infrastructure issues
  • Centralized, decentral, distrib

26
Features of Input/Output
  • Input human understandable data turned into
    machine readable form (digitize)
  • Output machine readable data turned into human
    readable form
  • Importance of dots in I/O
  • We often use dots (pixels) to store characters or
    images
  • Resolution -- as the number of dots increases,
    the better the image
  • Importance of sampling in I/O
  • Continuous reality (video,sound)
  • Sample snapshot

27
Input devices
  • Purpose to translate incoming data into machine
    readable form (digitize)
  • Keyboard - translate keystroke to byte
  • Pointing devices - translate movement or pressure
    to bits
  • Graphic input - scanners
  • Audio Input - sounds to bits
  • microphones -- record only
  • voice-input devices -- interpret
  • Video Input - images to bits
  • Scanner - creates a map of dark/light dots
  • Digital Cameras - digitizes snapshot of reality

28
Output Devices
  • Video - translate bits to images for display
  • Monitors (Screen)
  • CRT, CRT Flat screen, LCD Flat panel
  • Electron gun, gas plasma, crystals
  • Hard copy - translate bits to characters or
    pictures on paper
  • Printers
  • ink-jet vs. laser
  • Audio - translate bits to sound
  • Speakers
  • Headsets

29
Input in Organizations
  • Different from home because
  • Biggest problem - human beings…

30
Input Devices in Organizations
  • Input to aid humans
  • graphics tablet used with stylus
  • head/eye position trackers
  • touch screens
  • voice-input
  • Input to replace humans
  • OCR (optical character recognition)
  • Optical Codes -- ex bar code
  • MICR (magnetic ink character recognition)
  • Magnetic stripe technology (ex credit card)
  • Smart Cards
  • Intelligent Scanners
  • Handwriting Recognition Devices

31
Output in Organizations
  • Display
  • larger monitors for desktop
  • wall displays, flat panel screens
  • projectors
  • Printers
  • Fast/High Volume laser Printers
  • Color Laser
  • Impact printers
  • Dot-Matrix
  • Line printers
  • Thermal Printers
  • Plotters

32
Output in Organizations (contd)
  • Audio
  • voice synthesizers
  • prerecorded voice
  • Video
  • CD-ROM burners
  • microfilm/microfiche
  • archival storage

33
Hardware Features and Issues
  • CPU
  • Memory
  • Secondary Storage
  • Policies
  • Technology
  • Input devices and organizations
  • Output
  • Printers
  • Monitors
  • Audio/Video

34
Help When Buying a PC
35
Chip comparisons
  • Intel (Celeron, PentiumIII, Pentium 4)
  • Pentium 4
  • clock (1.4 - 2.8Ghz), 512 L2 (half speed)
  • 5.33 or 4 Ghz bus to memory
  • Pentium III
  • clock (850Mhz - 1.8), 512 L2, 1 or 1.33 Ghz bus
  • Celeron (value chipset)
  • Pentium chip 128 L2 (full sped)
  • comparable bus
  • AMD (Duron Athlon Athlon XP)
  • double L1, same or double L2 (full speed)
  • similar clock speed

36
Todays Memory
  • SIMM, DIMM
  • bank of memory chips on a circuit board
  • Dynamic RAM (constant refreshing)
  • DRAM -- pipelined
  • S-DRAM - synchronized DRAM
  • DDR S-DRAM - dual channel (tick/tock)
  • R-DRAM (rambus) - memory processor
  • Static RAM (less refreshing needed)
  • costs more, use in cache

37
Add-On Recommendations
  • Video Card or Graphics Accelerator
  • get AGP bus, AGP slot and AGP card
  • AGP Advanced graphics port standard
  • memory (8 mb of DRAM or VRAM)
  • MPEG (motion picture std)
  • 3D engine
  • Sound Card
  • sampling rate -- higher the better
  • Wavetable vs. FM synthesis
  • is sound of instrument recorded or synthesized?
  • MIDI (music standard)

38
Bus Standards May Need
  • Universal Serial Bus (USB) and Firewire
  • Still one character at a time but has a smarter
    processor
  • Port can handle multiple devices
  • Daisy Chain
  • USB Hub
  • Use with USB devices (ex flash drive)
  • Other specialized buses
  • AGP (graphics),
  • Hard disk (SCSI, IDE),
  • Music (MIDI),
  • Network (T-connector or IRDA for infrared
    wireless)

39
Secondary Storage Issues
  • Disk Controllers
  • Some controllers let you attach more drives than
    others
  • IDE(ATAPI) -- 2 drives max, slow (5400 or 7200
    RPM)
  • bus speed up to 100mhtz
  • SCSI -- 7 drives, faster (10k RPM)
  • SCSI Ultra -- 14 drives, fastest
  • For home use IDE is fine
  • Photographic CD stds
  • Kodak Photo CD series
  • Flash PIX

40
Screen Issues
  • Size of Screen
  • VIS -- viewable area (15)
  • Quality of Picture
  • Dot Pitch -- space between dots
  • .25 or smaller
  • Non-interlaced less flicker
  • Refresh Rate -- 75 hz or better
  • Standard SVGA

41
Guidelines
  • CPU -- older one ok
  • especially if has cache (synch, full-speed?)
  • Monitor --
  • spend less now, upgrade later OR
  • Buy high, use w/ new PCs later
  • Hard Drive --
  • get a moderately large one because
  • can add more later (hard drive)
  • ask about number of IDE and SCSI controllers

42
Guidelines (contd)
  • Memory --
  • leave room to expand
  • considerations
  • degree to which use multimedia
  • volume of software, files you will have
  • degree you use the internet
  • windows environment (XP 128mb minimum)
  • Expansion
  • bays (how many unused doors on box?)
  • expansion slots (how many unused?)
  • power supply (200 watt or better)
  • may need more power from wall socket
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