Chapter 3 - computer n network architectures

computers

• computes

• electronic device that stores, retrieves, process data

• no longer have to look like traditional pc/laptop

  • more mobile

• recognize binary digits (bit): 0 n 1

supercomputer

• for extremely complex calculations

• process huge amts of info quickly

mainframe enterprise level supercomputer

• handle huge amt of data n transactions while supporting many users at same time

server

• robust in terms of speed n memory

• provide data, applications, or other services over a network

microcomputer

• personal

• systems based on single-chip microprocessors

minicomputer

• multi-user computers

• in mid range of computing spectrum

transistors

• tiny electronic switches inside computer chip

• more = computer more powerful

• doubled every 2 yrs

moore’s law

• everything from speed to size to cost per unit of power doubles every 18 months

computer bits

• 0 n 1

• used to represent all kinds of info

  • text, image, etc

• 8 bits = 1 byte (256 # combos)

texts

• represented by 8-bit alphanumerical combos(ASCII table)

• unicode is used for more characters

images

• represented by pixels

• 1 black/white pixel =1 bit

• use more storage than texts so need more network capacity

1000 bytes

• 1 kilobyte (1k)

1000 kilobyte

• 1 megabyte (1 meg)

1000 megabyte

• 1 gigabyte (1 gig)

1000 gigabyte

• 1 terabyte

1000 terabyte

• 1 petabyte

1000 petabyte

• 1 exabyte

1000 exabyte

• 1 zettabyte

1000 zettabyte

• 1 yottabyte

  • 1024⁸ bytes

software program

• do tasks for user (EHR or spreadsheet)

computer hardware

• physical components

  • stuff that makes up system

central processing unit (CPU)

• carries out instructions n processes info (brain)

  • related to data processing speed

• where chip is

processing speed

• hertz (clock speed) = 1 cpu clock (internal) cycle / sec

  • clock speed alone don’t tell us which computer is faster

• today’s range = megahertz (MHz - million) → gigahertz (GHz - billion)

floating point instructions per sec (FLOP)

• measures how much math work computer do per sec

• FP= calculations involving #s that may contain decimal points

• Gflops= 1B of FLOPS/sec

random access memory (RAM)

• working mem (short-term) lost when computer turned off

auxiliary storage

• data stored permanently (long term)

• archival storage

  • tape

  • hard disks

  • optical drives

  • cloud

input devices

• send info to computer

  • keyboard

  • mouse

output devices

• provide info back to ppl

  • monitor

  • printer

computer software

• instructs hardware what to do

operating systems

• manage software programs to perform tasks

  • runs the comp

• layer between computer hardware n applications we use

application programming interfaces (APIs)

• for applications to communicate n exchange data over networks

basic programming lang

• common in early days of PCs

MUMPS programming lang

• used in early medical applications

• renamed to M w/ modern enhancements

C , C++ , C# (c sharp)

• used in modern applications

python

• scripting lang

• larger scale use like in machine learning applications

java

• attempt to create standard lang for web applications

javascript

• scripting lang for web browsers

R

• lang for stats n data analytics

if-then-else logic

• if condition true, then perform action

  • if not, else move on

  • ex

    • if 85% doesn’t fall between 100-90, then move on to check if it falls between 89-80

open-source software

• organizations have more access to underlying codes

• free (doesn’t mean no cost) and shareable (depends on copy-right)

database

• organized collection of data (physical data)

  • found, retrieved, used efficiently

• can be various elements (diff types n sizes)

  • patient name, DOB, etc

• allows end user to extract data

• used by diff applications n departments

• store images, vids, sounds, texts

database management system (DBMS)

• application housing database

  • software

• allow for extraction n manipulation of data

patient database/table - column

• represents one specific type of info for every record

patient database/table - row

• represents 1 complete record

database advantage

• store large amt of data

• security enforced

• no redundancy

• relationships defined

• build user interface or application based on data

• controls user entry as validations for each element

  • data validation

excel

• for organizing n analyzing info

internet path

• user request → home network sends request to internet service provider (ISP) →ISP allow access → DNS connects IP address → target server

Internet service provider (ISP)

• gives user access to internet by sending request to DNS

TCP/IP

• help move data between device n destination (with rules)

• main standard

• 4 layers

  • application

  • transport

  • internet

  • network

domain name service (DNS)

• connects website name to IP address

Hypertext protocol (HTTP)

• provide rules for requests n responses on web

  • exchange of data

uniform resource locator (URL)

• web address that identifies where particular resource is

• in address bar of browser

web server

• sends info or services to other computers

hypertext markup lang (HTML)

• lang used to structure/format the content of web page

  • wrote web pages

dynamic host configuration protocol (DHCP)

• automatically provide device w/ network setting

internet

• largest most important scale of international network

• goal

  • independent platform to share info

global network-of-networks

• smaller networks connected tg

• use telecommunication protocol / internet protocol stack (TCP/IP) as communication standard

advanced research projects agency network (ARPANET)

• late 1960

• before WWW

• tie tg universities n research organizations

world wide web (WWW)

• 1989

• introduced web browser

• use internet to access websites n web-based info

interoperability

• ability to communicate with other devices

• achievement depends on global use of standards

Hub

• hardware

• older tech that sends info to all connected devices

  • connect device w/ local network

• connects multiple devices

• shares bandwidth

switches

• hardware

• directs info to specific device that needs it (traffic cops)

  • connects device w/ local network

• connects multiple devices

• full bandwidth

node

• device with address on a network that can communicate with other devices

internet service provider (ISP)

• connects computers to internet

• verizon , AT&T

components needed for internet connection

• IP address

• subnet mask

IP address

• unique , assigned to network

• allows network to identify diff devices n make sure info get to right one

subnet mask

• works with IP address

• division of network

• determines which part of IP address represents network

2 versions of IP address

• IP version 4 (IPv4) - 32-bit address length

  • limited # of available addresses

• IP version 6 (IPv6) - 128-bit

  • created bc more devices connected to network

before internet

• separate (disparate) businesses can’t easily exchange data

• data stayed on local pc/server

web services

• task specific applications that let diff systems exchange info over a network

• runs on a server

web service types

• RESTful (representational state transfer)

  • one program sends request n receives response over network

• SOA (service oriented architecture

  • organize software into separate services that diff applications can use

web service advanatges

• platform n program independent

  • diff sys. don’t have to use same software/program to exchange info

• client-server model

• integrated

RESTful

• clients n servers communicate w/o continuous connection

  • asynchronous manner

    • text/call not at same time

Open System Interconnection Model (OSI)

• conceptual model for understand network architectures

• divides computer-computer communication into 7 layers (OSI Stack)

• TCP/IP based on/subset of it

7 OSI layers

• top

  • application

  • presentation

  • session

  • transport

  • network

  • data link

  • physical

application layer

• user/software accesses network services

  • http

  • email

  • HL7

• opens what was sent or creates whats sent

  • info exchange

presentation layer

• formats/translates data

• encrypts / decrypts

session layer

• starts, maintains, ends communication between 2 sys.

transport layer

• delivers data between sys.

  • correctly n in order

network layer

• IP address n routing takes place

data link layer

• communication between devices on local network

  • use MAC addresses to transfer data frames

physical layer

• physically transmits data

  • cables

  • hubs

ways to access the internet

• dial-up modem

• wireless fidelity (wifi)

  • wireless connection

• digital subscription line (DSL)

  • shared among small businesses thru existing tel. lines

• mobile telecommunication (3g/4g/5g)

• cable modem (digital or fiber optic) - cable providers

• T1

  • digital lines linking buildings (within company)

• satellite

data transfer rate

• bps = bits per sec

• kbps (thousands) < mbps (millions) < gbps (billions)

theoretical max speed

• fastest speed tech can go under ideal conditions

typical speed range

• actual/normal speed

  • lower

downlink

• speed of receiving data

  • opening image

uplink

• sending info

• speed of data leaving device

data transfer affected by

• bandwidth

• packet loss

• end-to-end delay

• jitter

bandwidth

• size of pipe to transmit packets (traveling info is broken to smaller pieces)

• how much data can travel at once (capacity)

packet loss

• data fails to reach destination (rare)

  • IP transmission Control Protocol (TCP) checks that packet arrived or re-send

  • User Datagram Protocol (UDP) doesn’t guarantee arrival

end-to-end delay

• amt of time needed for data roundtrip

  • takes long

    • high latency/delay

jitter

• random variation in packet delay (inconsistent)

networks

• group of computers linked tg to share info

• provide internet access to multiple users

• range from small (connect several devices) to large (connect entire organization)

networks named based on

• connection method

• size

• configuration

network topology

• layout of network

to be connected to network, computer must have

• IP - mark computer location (address)

• subnet mask - if connected to subnetwork (my network)

• dynamic host configuration protocol (DHCP) - assigns IP address

• domain name server (DNS) - domain name into IP address

• default gateway - send info outside local network

wide area network (WAN)

• telecommunication network that covers large geographical area

  • hospitals across nyc

• for computer networking

telecommunications

• connects computer or smaller networks

• sends info over distance electronically

local area network (LAN)

• computers connected within small proximity (home, office, hospital, unit)

• wired or wireless