This document discusses computer and network architectures. It describes basic computer components like the CPU, memory, and input/output devices. It also discusses different types of networks like personal area networks (PANs) and local area networks (LANs). PANs connect nearby devices using technologies like Bluetooth, while LANs link computers in an office using wired or wireless connections. The document explains internet protocols like TCP/IP that allow global communication across networks.

1. Chapter 3: Computer and Network Architectures
Robert Hoyt MD
William Hersh MD
After viewing the presentation, viewers should be able to:
Describe the basic components of computing
Discuss the Internet and World Wide Web
Understand the importance of networks in the field of medicine
Compare and contrast wired and wireless local area networks
(LANs)
Describe the newest wireless broadband networks and their
significance
Learning Objectives

2. Types:
Microcomputer
Minicomputer
Personal computer (PC) (Desktop)
Supercomputer: mainframe enterprise level
Laptop
Server: robust in terms of speed and memory
Mobile
smartphone
tablet
Computers
Computers recognize the binary digit (bit): 0 and 1
Bits represent everything in a computer: text, images, etc.
8 bits is a byte which can have 256 combinations
Text is represented by 7 bit alphanumeric combinations
(ASCII). For more text characters Unicode is used. For
example, 16 bit UTF means 16 bit
Images are represented by pixels. Each black/white pixel is 1
bit. Images are “memory hogs”, compared to text
Computers and Data

3. 1000 bytes = 1 kilobyte (or 1K)
1000 kilobytes = 1 megabyte (or 1 meg)
1000 megabytes = 1 gigabyte (or 1 gig)
1000 gigabytes = 1 terabyte
1000 terabytes = 1 petabyte
1000 petabytes = 1 exabyte
1000 exabytes = 1 zettabyte
1000 zettabytes = 1 yottabyte = 1024 bytes
Kilobyte to Zettabyte
Central processing unit (CPU): where the computer chip resides
and is related to data processing speed
Memory: random access memory (RAM) is the working memory
that is lost when the computer is turned off.
Auxiliary storage: active storage is where data is stored that is
needed continuously. Archival storage can refer to tape, hard

4. disks, optical drives or cloud
Input and Output devices: keyboards, mouse, monitors, etc.
Computer Hardware
Software programs instructs the hardware what to do
Application Programming Interfaces (APIs) are a common way
now for computers to react with other programs or apps
Operating systems provide a standardized way for software
programs to perform tasks
Computer Software
C, C++, C# – used in many modern applications
MUMPS – used in many early medical applications, now
renamed to M and with many modern enhancements
BASIC – common in early days of PCs
Python – originated as “scripting” languages for Unix and Web,
but achieving larger-scale use, e.g., in machine learning
applications

5. Java – attempt to create standard language for Web applications
JavaScript – scripting language for Web browsers
R – emerging important language for statistics and data
analytics
Programming Languages for Computing
Source code is free and shareable. Examples are Linux, Apache,
Mozilla, OpenOffice, etc.
Resources for open source software in healthcare:
https://sourceforge.net/directory/business-
enterprise/enterprise/medhealth
https://en.wikipedia.org/wiki/List_of_open-
source_health_software
Online Registry of Biomedical Informatics Tools (ORBIT) –
https://orbit.nlm.nih.gov/
Open Source Software

6. Spreadsheets are considered flat files or one dimensional;
unlike relational databases which link tables together for more
robust storage and queries
A database management system (DBMS) is a program that
manages the database
Most common language to query the database is structured
query language (SQL)
There is a trend towards non-relational database systems, like
NoSQL for large “big data”
Database Systems
Note the primary key (Employee ID = 1) in the first table is
linked to the second table (Salary)
SQL Database Schema

7. The Internet is the largest and arguably most important large
scale international network
The Internet is a global “network-of-networks” using the
Telecommunications Protocol/Internet Protocol stack (TCP/IP)
as the communications standard. The TCP/IP stack allows for
layering of different standards and technologies based on the
participants in an exchange and the payload being exchanged
The Internet began in the late 1960 as a network known as
Advanced Research Projects Agency Network (ARPANET)
capable of tying together universities and research organizations
securely
The Internet and World Wide Web
The World Wide Web (WWW) operates on top of the Internet
and was created by Tim Berners-Lee in 1989
The WWW introduced the web browser, a software program
that allows for connection to web servers over the Internet using
Hypertext Transfer Protocol (HTTP)
Web pages are written using Hypertext Markup Language
(HTML), an implementation of a markup language, or method
for defining formatting of text in a document, which has become
synonymous with the Web
The Internet and World Wide Web

8. Achieving interoperability on the Internet depends on global use
of standards
Standards exist for the exchange of data, such as HTTP; the
format of data, such as HTML, and the transport of data, such as
TCP/IP
In a TCP/IP network, each device (host) must have an Internet
Protocol (IP) address. IP addresses can be distributed amongst
different tiers of lower layer networks, or “sub-networks”
The Internet and World Wide Web
In order for addressing to function properly in the presence of a
sub-network, the machine must both have an IP address and a
routing prefix or “subnet mask” (example: IP address of
192.168.10.1 and subnet mask of 255.254.254.0) in order for it
to be considered properly addressable by other network nodes
Two versions of IP addressing exists today, IP version 4 (IPv4)
which has been around for more than 40 years
IP version 6 (IPv6) is being used to phase out IPv4 before the
complete depletion of assignable addresses brings the growth of

9. the Internet to a complete halt
The Internet and World Wide Web
It is useful to think of the Internet as comprised of two main
components, protocols and hardware
Each machine addressable on a network is known as a node
Computers connect to the internet through an Internet Service
Provider (ISP) such as Bell South or AT&T
The Internet and World Wide Web
An electronic request for an IP address is sent via the network
link provided by the one’s ISP to a DNS server
The DNS server then matches the requested domain name and
responds with an IP address
The browser is now capable of sending an HTTP GET request
(again routed through one’s ISP provided link) to the IP address

10. returned from the DNS request
The browser can now render and display the document defined
by the HTML response on the user’s screen
The Internet and World Wide Web
A message must be sent using small packets of information that
can arrive via different routes, useful when there is web
congestion, and are reassembled back at one’s computer
All traffic sent using TCP/IP (such as phone calls over the
internet (VoIP) and email) are sent using packets
A router is a node which directs the packets on the Internet.
The role of ordering these packets and making sure that they
make it to their intended recipient in the proper structure is one
of the jobs of TCP/IP
The Internet and World Wide Web
The Uniform Resource Locator (URL) is a specified address to a
specific resource (e.g. http://www.google.com); the first part of

11. the URL is the protocol identifier and the rest is the resource
name
The protocol identifier and the resource name are separated by a
colon and two forward slashes. As an example,
http://uwf.edu/uwfmain/about describes HTTP as the
protocol,“uwf.edu” as the server to which the HTTP request will
be made, and “/uwfmain/about” as the path to the resource
being requested. The most common domains end in .com, .edu,
.org, .net, .mil, .gov and .int
The Internet and World Wide Web
How the Internet Works
Prior to the advent of the Internet, disparate businesses and
health care entities were not able to easily exchange data;
instead data resided on a local PC or server
Now, much of what we do is “is in the cloud”

12. Web services are task specific applications which are deployed
in a platform independent manner via a series of transactions to
and from other web-aware applications/services over a network
(such as the Internet)
Web services can be broken down into two categories: RESTful
services and SOA services
Web Services
Representational State Transfer (or RESTful) services are
lightweight services which use existing Internet infrastructure
and World Wide Web (WWW) concepts as their backbone
REST is an architecture, not a standard with endless
possibilities as to how REST can be applied to act as a service
bus
Communication with a RESTful service is a relatively quick
process and can utilize any existing content standard for
packaging its messaging. Most commonly, a RESTful service
will use XML or JavaScript Object Notation (JSON) for this
content delivery
RESTful Services

13. Operation Types (GET, DELETE, POST, PUT). These HTTP
methods can provide four different points of access to a
RESTful service. If a URI or URL identifies an object, the
HTTP operation type defines an accessor method to that object
(e.g. GET a list, POST an update, PUT a new record, DELETE
a purged record)
MIME Type (Multipurpose Internet Mail Extensions) is a means
of communicating the content type used within a message
transferred over the Internet. Typically, in a RESTful service,
this would be XML or JSON, but it could be any other type
RESTful Services
RESTful Operations

14. SOA is based on SOAP, a protocol standard for interacting with
web services
These services require a set of standards for content and a
service oriented architecture (SOA) stack, a collection of
services
The most common standards used in web services transactions
are HTTP, as the internet protocol, with XML as the delivery
language
Service Oriented Architecture (SOA) Web Services
SOAP (Simple Object Access Protocol): a communication
protocol between applications. It is a XML-based platform
neutral format for the invocation and response of web services
functions over a network
WSDL (Web Services Description Language): a XML document
used to describe and locate web services. A WSDL can inform
a calling application as to the functionality available from a
given service, as well as the structure and types of function
arguments and responses
UDDI (Universal Description, Discovery and Integration): a
directory for storing information about web services, described
by WSDL. UDDI utilizes the SOAP protocol for providing
access to WSDL documents necessary for interacting with
services indexed
Service Oriented Architecture (SOA) Web Services

15. UDDI provides the service registry (like the yellow pages) and
WSDL describes the services and the requirements for their
interaction
A service requester seeking a web service would search a
service directory for a function that meets a need using a
structured language
Once the service provider is located, a SOAP message can be
sent back and forth between the service requester and service
provider (next slide)
SOA Web Services
SOA Web Services

16. A conceptual model was created in 1984 to help understand
network architectures
It divides computer-to-computer communication into seven
layers known as the OSI Stack
The Open Systems Interconnection (OSI) Model
Application. This is the layer where applications access
network services. Examples: software for database access,
email and file transfer and the Internet protocols FTP, HTTP
and SMTP
Presentation. This layer translates (formats) the data for the
application layer for the network. Examples: data encryption
and compression
Session. This layer establishes, maintains and terminates
“sessions” between computers
The OSI Model Layers

17. Transport. This layers deals with error recognition and
recovery and handles message size issues and can send receipt
acknowledgments. The Internet protocol related to this is TCP
Network. This layer is involved with message control,
switching and routing. It translates logical addresses into
physical addresses
Data link. This layer packages data from the physical layer into
frames (special packets) and is responsible for error free from
transfer from one computer (node) to another
The OSI Model Layers
Physical. This layer deals with the unstructured raw data
stream from the other layers. Specifically, it encodes data and
decides whether the bits will be sent via a digital or analog
mode and decides if the bits will be transmitted as electrical or
optical signals. This layer is involved with communication with
devices. Examples: USB, Bluetooth and RS-232
The OSI Model Layers

18. A network is a group of computers that are linked together in
order to share information
A network can share patient information as well as provide
internet access for multiple users
Networks can be small, connecting just several computers in a
clinician’s office or very large, connecting computers in an
entire organization in multiple locations
There are several ways to access the internet: dial-up modem,
wireless fidelity (WiFi), a Digital Subscription Line (DSL),
3G/4G telecommunication, cable modem or T1 lines
Networks
Transmission methodTheoretical max speedTypical speed
rangeDial-up modem56 Kbps56 KbpsDSL6 Mbps1.5-8Mbps
downlink/128 Kbps uplinkCable modem30 Mbps3-15 Mbps
downlink/1-3 Mbps uplinkWired Ethernet (Cat 5)1000 Mbps100
MbpsFiber optic cable100 Gbps2.5-40 GbpsT-1 line1.5 Mbps1-
1.5 MbpsWireless 802.11g
Wireless 802.11n54 Mbps
300 Mbps1-20 Mbps
40-115 MbpsWiMax70 Mbps54-70 MbpsLTE60 Mbps8-12

19. MbpsBluetooth24 Mbps1-24 Mbps3G2.4 Mbps144-384
kbps4G100 Mbps10-70 MbpsSatellite10 Mbps10 Mbps
Data Transfer Rates
Bandwidth is the size of the pipe to transmit packets (a
formatted data unit carried by a packet mode computer network)
Packet loss is an issue because packets may rarely fail to reach
their destination. The IP Transmission Control Protocol (TCP)
makes sure a packet reaches its destination or re-sends it. The
User Datagram Protocol (UDP) does not guarantee delivery and
is used with, for example, live streaming video
End-to-end delay is the latency or delay in receiving a packet.
With fiber optics the latency is minimal
Jitter is the random variation in packet delay and reflects
Internet spikes in activity
Data Transfer Affected By:

20. Networks are named based on connection method, as well as
configuration or size. As an example, a network can be
connected by fiber optic cable, Ethernet or wireless. Networks
can also be described by different configurations or topologies.
They can be connected to a common backbone or bus, in a star
configuration using a central hub or a ring configuration
Network Types
A PAN is a close proximity network designed to link phones,
computers, PDAs, etc. The most common technology to create
a wireless personal area network or WPAN is Bluetooth (BT)
BT is designed to wirelessly connect an assortment of devices at
a maximum distance of about 300 feet with the most recent
Bluetooth devices (version 5.0). It does have the advantages of
not requiring much power and connecting automatically. It
operates in the 2.4 MHz frequency range
The most common application of Bluetooth today is as a
wireless headset to connect to a mobile phone but wearable
technology (e.g. fitness devices) is a close second
Personal Area Networks (PANs)

21. Bluetooth can be used to wirelessly connect computers to
keyboards, mice, printers, PDAs and smartphones
Security must be enabled due to the fact that even though the
transmission range is short, hackers have taken advantage of
this common frequency
Bluetooth Smart or Low Energy 5.0 requires less power, has
better battery life and is less expensive. The frequency is the
same but the range is less (about 50 meters)
Personal Area Networks (PANs)
PANs can also use other standards: Infrared to connect devices
using the IrDA standard, ZigBee networks, Wireless USB and a
body area networks (BANs)
A wireless body area network (WBAN) is also known as a body
sensor network which is gaining importance in healthcare
Another wireless sensor network protocol known as ANT™ is
available for ultra-low power applications. The proprietary
network operates on the 2.4 GHz ISM band
Personal Area Networks (PANs)

22. LANs generally refer to linked computers in an office, hospital,
home or close proximity situation
A typical network consists of nodes (computers, printers, etc.),
a connecting technology (wired or wireless) and specialized
equipment such as hubs, routers and switches
LANs can be wired or wireless
Local Area Networks (LANs)
To connect several computers in a home or office scenario, a
hub or a network switch is needed
Routers direct messages between networks and the Internet;
whereas, switches connect computers to one another and prevent
delay
Unlike Hubs that share bandwidth, switches operate at full
bandwidth. Switches are like traffic cops that direct
simultaneous messages in the right direction
Wired LANs

23. To handle larger enterprise demands Gigabit Ethernet LANs are
available that are based on copper or fiber optics. Cat5e or
Cat6 cables are necessary
Greater bandwidth is necessary for many hospital systems that
now have multiple IT systems, an electronic medical record and
picture archiving and communication systems (PACS)
Typical LAN shown on next slide
Wired LANs
Typical Wired LAN Schema
Phone lines can connect a computer to the internet by using a

24. dial-up modem. The downside is that the connection is
relatively slow
Digital subscription lines (DSL) also use standard phone lines
that have additional capacity (bandwidth) and are much faster
network connection than dial up
DSL also has the advantage over modems of being able to
access the internet and use the telephone at the same time
Wired LANs
Power lines are another option using standard power outlets to
create a network. PowerPacket® is inexpensive to install and
claims data transfer speeds of 14 Mbps
Ethernet is a network protocol and most networks are connected
by fiber or twisted-pair/copper wire connections. Ethernet
networks are faster, less expensive and more secure than
wireless networks. The most common Ethernet cable is
category 5 (Cat 5, 5e) unshielded twisted pair (UTP)
Wired LANs

25. Wireless networks are based on the Institute of Electrical and
Electronics Engineers (IEEE) 802.11 standard and operate in the
900 MHz, 2.4 GHz and 5 GHz frequencies
Wireless networks have become much cheaper and easier to
install so many offices and hospitals have opted to go wireless
This allows laptop/tablet PCs and smartphones in exam and
patient rooms to be connected to the local network or internet
without the limitations of hardwiring but it does require a
wireless router and access points
Wireless LANs
802.11ac is the newest standard that can operate at speeds up to
900 Mbps with a frequency of 2.4 and 5 GHz
The network router is usually connected to the Internet by an
Ethernet cable to DSL or a cable modem. Security must be
established using an encryption scheme such as WiFi Protected
Access II (WAP2) encryption
Each device on a network has a unique address (MAC) and
routers can have security lists which only allow known devices
or MACSs into the network
Wireless LANs

26. Wireless LAN (WLAN)
GANs are networks that connect other networks and have an
unlimited geographic area. The problem with broadband
technology is that it is expensive and the problem with WiFi is
that it may result in spotty coverage
These shortcomings created an initiative known as Worldwide
Interoperability for Microwave Access (WiMax), using the
IEEE 802.16 standard
This 4G network is about 10 times faster than 3G and has
greater capacity which is equally important
Global Area Networks (GANs)

27. The goal is to be faster than standard WiFi and reach greater
distances, such that it might replace broadband services and
permit widespread wireless access to the internet by PCs or
phones
The introduction of one 4G network (WiMax) was so slow that
major carriers adopted Long Term Evolution (LTE) WiFi
Operating in the 700 MHz range it has maximum download rates
of 100 Mbps and upload rates of 50 Mpbs
There will be a slow roll out of 5 G in 2018
Global Area Networks (GANs)
In this case the home computer is the client and is attached to
the network at work by communicating with a VPN server
associated with that network
The Internet can serve as the means of connection with VPN
working over both wired and wireless LANs
“Tunneling protocols” encrypt data by the sender and decrypt it
at the receiver’s end via a secure tunnel. In addition, the
sender’s and receiver’s network addresses can be encrypted
A physician at home may use a VPN to access the work EHR
Virtual Private Networks (VPNs)

28. Virtual Private Networks (VPNs)
Informaticians need to understand computer and network
technologies
Clinicians and IT staff must have an excellent understanding of
office networks and the related required security
Wireless networks have become attractive due to faster speeds
and lower costs
Wireless broadband has arrived to provide faster Internet access
for all
Conclusions