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ALHEChapter3ComputerandNetworkArchitectures.pptxChapter 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
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
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 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
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
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
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
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 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 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 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”
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
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
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
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
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
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
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 method | Theoretical max speed | Typical speed range |
| Dial-up modem | 56 Kbps | 56 Kbps |
| DSL | 6 Mbps | 1.5-8Mbps downlink/128 Kbps uplink |
| Cable modem | 30 Mbps | 3-15 Mbps downlink/1-3 Mbps uplink |
| Wired Ethernet (Cat 5) | 1000 Mbps | 100 Mbps |
| Fiber optic cable | 100 Gbps | 2.5-40 Gbps |
| T-1 line | 1.5 Mbps | 1-1.5 Mbps |
| Wireless 802.11g Wireless 802.11n | 54 Mbps 300 Mbps | 1-20 Mbps 40-115 Mbps |
| WiMax | 70 Mbps | 54-70 Mbps |
| LTE | 60 Mbps | 8-12 Mbps |
| Bluetooth | 24 Mbps | 1-24 Mbps |
| 3G | 2.4 Mbps | 144-384 kbps |
| 4G | 100 Mbps | 10-70 Mbps |
| Satellite | 10 Mbps | 10 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:
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)
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)
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
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 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
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
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)
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)
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
