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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

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Client server architecture
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 tier vs 3 tier architecture
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


Three tier or n tier architecture
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


E commerce models pure plays
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.


It fundamentals

IT Fundamentals

1. Total Cost of Ownership

2. How Computers Work

3. Organizational Computing

4. Storage

5. Input/Output

6. Buying a Desktop Tutorial


Total cost of ownership
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


Tco takehome project
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


Basic unit and upgrades
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)


Other tco issues
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)


Data representation vol speed
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 0’s and 1’s 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.


What a cpu does

Input

Devices

CPU

Output

Devices

Storage

Devices

What a CPU Does

Memory


What a cpu does1

Input

Devices

CPU

Storage

Devices

Output

Devices

What a CPU Does

Data Bus

Memory

External Bus

or I/O Bus

or Local/Expansion Bus

Internal Bus


Typical steps
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?


What a cpu does2

Input

Devices

Output

Devices

Storage

Devices

What a CPU Does

Memory

disk

cache

CPU +

external

cache

internal

cache

DMA hard drive

disk

controller

Sound card &

Video card


Computer platforms
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


Parallel processing
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


Primary storage fast to slow
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)


Secondary storage concepts
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


Secondary storage features
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


Magnetic storage devices
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


Optical storage
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


Memory tech as sec storage
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


Storage in organizations
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


Enterprise storage architectures
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)


Storage issues
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


Features of input output

. . .

.

. . .

.

. . .

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


Input devices
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


Output devices
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


Input in organizations
Input in Organizations

  • Different from home because:

  • Biggest problem - human beings…


Input devices in organizations
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


Output in organizations
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


Output in organizations cont d
Output in Organizations (cont’d)

  • Audio

    • voice synthesizers

    • prerecorded voice

  • Video

    • CD-ROM burners

    • microfilm/microfiche

      • archival storage


Hardware features and issues
Hardware Features and Issues

  • CPU

  • Memory

  • Secondary Storage

    • Policies

    • Technology

  • Input devices and organizations

  • Output

    • Printers

    • Monitors

    • Audio/Video



Chip comparisons
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


  • Today s memory
    Today’s 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


    Add on recommendations
    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)


    Bus standards may need
    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)


    Secondary storage issues
    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


    Screen issues
    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


    Guidelines
    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


    Guidelines cont d
    Guidelines (cont’d)

    • 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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