Chapter 3 Computer and Network ArchitecturesRobert Hoyt MDW.docx
- 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