BUSS 909 Office Automation Intranets Lecture 2 Data

BUSS 909 Office Automation & Intranets Lecture 2 Data Communication Technologies Clarke, R. J (2001) L 909 -02: 1

Notices n Assignment 1: n Pickup Assignment 1 Handout now n Assistance with Assignment 1: n Buy a copy of Woodward-Kron’s book from Uni. Centre Bookshop (if available) n Also refer to Academic Essay Writing Notes in Closed Reserve n Pickup a copy of Learning Development Student Services Brochure and Timetable Clarke, R. J (2001) L 909 -02: 2

Agenda L 909 -02 n Data Communications Principles and Technologies n in this lecture we consider only the Data Communications technologies relevant to Office Automation n we will revisit this topic in subsequent lectures Clarke, R. J (2001) L 909 -02: 3

Agenda T 909 -01 n Writing for Commerce: Essays and Case Studies (differs from the published schedule) Clarke, R. J (2001) L 909 -02: 4

Office Automation Overview Clarke, R. J (2001) L 909 -02: 5

Office Automation n the greatest proportion of work involves information in textual form: n procedures n reports n memoes n applies to: n service industries, bureaucracies, public sector organisations, and small-large private sector organisations Clarke, R. J (2001) L 909 -02: 6

Office Automation n additionally, decision making (work about work) in any organisation is conducted in groups n these groups almost always are involved in language activities (reading, writing etc) n board room meetings n brainstorming sessions n formal reviews n shareholders meetings Clarke, R. J (2001) L 909 -02: 7

Office Automation n technologies called OA systems have been developed since the mid-1970 s to cope with these kinds of work n generally these systems are based on networks of various kinds (we review the various types and some standard terminology used to describe them this lecture) Clarke, R. J (2001) L 909 -02: 8

Office Automation n these technologies at that time were very expensive (special hardware and software) n the leader was Wang Computers n by the mid 80 s experimental systems were being researched to support group-based activities- this research is still ongoing (Nunamaker et al 1991 40 -61) Clarke, R. J (2001) L 909 -02: 9

Office Automation n OA systems were augmented with systems that had similar functionality n other names that can be found include: OIS- Office Information Systems; EMS- Electronic Meeting Systems; Collaborative Management Systems Clarke, R. J (2001) L 909 -02: 10

Office Automation n much of this has been superceded by developments in the marketplaceincluding proprietary integrated software eg. Lotus Notes; Microsoft Office 97 n also the WWW and graphical browsers provide a way for organisations to transform desktop computing to webtop computing Clarke, R. J (2001) L 909 -02: 11

Office Automation n but the research that led to these systems is still relevant as we try to implement the same functionality in the form of intranets and extranets (private networks based on Internet technology) Clarke, R. J (2001) L 909 -02: 12

Office Automation n an additional trend is to create the virtual organisation, which again is based on theory and principles established and developed during the mid-1970 s n telework, remote work, mobile data systems etc Clarke, R. J (2001) L 909 -02: 13

Network Processing & Topologies Clarke, R. J (2001) L 909 -02: 14

Network Terms n topology = pattern of a network n circuit n transmission facility provides =>1 channels of communication eg/ phone line, microwave signal, optical cable n node n point in a network where circuits are interconnected by one or more units n may be other computers Clarke, R. J (2001) L 909 -02: 15

Network Processing (1) Timesharing Networks n oldest approach n introduced in 3 rd generation n consists of a single computer n performance limited to the computer Clarke, R. J (2001) L 909 -02: 16

Network Processing (2) Distributed Processing n when minicomputers became popular n companies started distributing minis and micros throughout the organisation n when interconnected the technique is called distributed computing or distributed data processing (DDP) Clarke, R. J (2001) L 909 -02: 17

Network Processing (3) Client/Server Computing n some functions are best handled locally and some are best handled centrally n blend of timesharing approach (central use) and distributed processing (local) n usually LANs but can be WANs n client: user has access to network by means of desktop computer n server: computer of any size which provides control of network function Clarke, R. J (2001) L 909 -02: 18

Network Topologies (1) n describes how multiple computers are connected together (eg/ distributed processing, client/server computing) on a network n several different topologies are available Clarke, R. J (2001) L 909 -02: 19

Network Topologies (2) n Star Network n central computer called the central node n guarentees centralised control n failure on central node causes failure over entire network Clarke, R. J (2001) L 909 -02: 20

Network Topologies (3) n Ring Network n does not include a central node n control is distributed throughout network n failure in any link causes problem for network n Hybrid Network n star & rings can be used together n when this occurs the topology is referred to as a Hybrid Topology Clarke, R. J (2001) L 909 -02: 21

Network Management, Planning & Control Clarke, R. J (2001) L 909 -02: 22

Network Management (1) n often critical to firms n network failures can be catastropic n require planning and control n need to be managed What would happen if a your banks ATM data comms network fails ? Clarke, R. J (2001) L 909 -02: 23

Network Management (2) n in large companies n network manager n network analysts n software analysts n datacom technicians n in small companies n LAN manager Clarke, R. J (2001) L 909 -02: 24

Network Management (3) Network Manager: n responsible for n planning n implementing n operating n controlling n responsible to CIO Clarke, R. J (2001) L 909 -02: 25

Network Management (4) Network Analyst n perform same function as systems analysts n restricted to communication-oriented systems Software Analysts n program & maintain datacom software Clarke, R. J (2001) L 909 -02: 26

Network Management (5) Datacom technicians n concerned with hardware and operations LAN Manager n found in smaller organisations n members of information services n generally a member of using organisation n may perform all of the duties of network manager Clarke, R. J (2001) L 909 -02: 27

Network Planning all activities that aim to anticipate firms networking needs Capacity planning n analyses & plans for traffic volumes Staff planning n people to manage network & skills Performance monitoring n analyse response times and potential changes Clarke, R. J (2001) L 909 -02: 28

Network Control n day-to-day monitoring of the network n involves fault detection, fault isolation, network restoration n firm needs standard procedures to implement network control Clarke, R. J (2001) L 909 -02: 29

Network Architectures Clarke, R. J (2001) L 909 -02: 30

Network Architectures (1) n variety of hardware & software n products available from: n computer manufacturers n common carriers n data coms specialist companies n many suppliers & standards is a ‘mixed blessing’ Clarke, R. J (2001) L 909 -02: 31

Network Architectures (2) n network architectures specify protocols n rule for interfacing (interconnecting) various units n all data coms devices will follow specific protocols n variety of units led to a small number of ‘industry’ standards Clarke, R. J (2001) L 909 -02: 32

Network Architectures (3) Industry standards include: n SNA (IBM) n BNA (Burroughs) n DSE (Honeywell) One of the most common data coms standards is called OSI Clarke, R. J (2001) L 909 -02: 33

Network Architectures (4) n SNA n Systems Network Architecture n developed by IBM because it marketed 200 different data coms products n one of the first standards developed n a proprietary standard Clarke, R. J (2001) L 909 -02: 34

Network Architectures (5) n SNA: n defines all activities involved in transmitting data through a network n transmitted from a user node n transmitted to a host node n transmitted through one or more intermediate nodes Clarke, R. J (2001) L 909 -02: 35

Network Architectures (6) n separates physical activities that transmit data n and logical activities that control transmission Clarke, R. J (2001) L 909 -02: 36

Network Architectures (7) n SNA n classifies logical activities into layers n layers insulate users from changes in the datacom hardware and software n layers have become a common strategy in other datacoms standards Clarke, R. J (2001) L 909 -02: 37

OSI Model Clarke, R. J (2001) L 909 -02: 38

OSI Model (1) n OSI = Open Systems Interconnection n almost all Network rely upon this Model to organise communications between Clients and Servers n uses layers like SNA to define physical and logical layers n 7 layers are used; all nodes have them Clarke, R. J (2001) L 909 -02: 39

OSI Model (2) n A layer at one node (user) ‘talks’ to its corresponding layer at the other (host) end n Layers 1 -3 needed at every node; Layers 4 -7 at host & user nodes only Clarke, R. J (2001) L 909 -02: 40

OSI Model (3) n 1: Physical Layer n Transmits the data from one node to another n eg. / RS 232 c n 2: Data Link Layer n Formats the data into a record called a frame n Performs error detection Beginning Flag Address Control Message Frame Check Ending Flag Clarke, R. J (2001) L 909 -02: 41

OSI Model (4) n 3: Network Layer n causes the physical layer to transfer the frames from node to node n 4: Transport Layer n enables user and host nodes to communicate with each other n synchronizes fast- and slow- speed equipment as well as overburdened and idle units Clarke, R. J (2001) L 909 -02: 42

OSI Model (5) n 5: Session Layer n initiates, maintains and terminates each session n sessions consist of all frames that comprise an activity, and all signals that identify beginning and end n eg. / log-on and user id routines to initiate sessions Clarke, R. J (2001) L 909 -02: 43

OSI Model (6) n 6: Presentation Layer n formats data for presenting to user or host n eg. / information to be displayed on users screen is formatted into proper number of screen lines and characters per line n 7: Application Layer n controls user input from the terminaland executes the user’s application program Clarke, R. J (2001) L 909 -02: 44

OSI Model (7) n Eg. / User needs host software n L 7 (application) takes request n L 6 (presentation) changes input data to correct format for transmission n L 5 (session) starts the session on the host machines n L 4 (transport) selects route from user to host n L 3 & 2 (network & data link) cause data to be transmitted through L 1 (physical) Clarke, R. J (2001) L 909 -02: 45

USER High OSI Model (8) HOST 7: Application Layer consists of application programs that use the network High 6: Presentation Layer standardises data presentation to applications 5: Session Layer manages sessions between applications 4: Transport Layer provides end-to-end error detection and correction 3: Network Layer manages connections across the network for the upper layers 2: Data Link Layer provides reliable data delivery across the physical link Low 1: Physical Layer Low defines the physical characteristics of the network media Clarke, R. J (2001) L 909 -02: 46

OSI Model (9) Intermediate Nodes User Node User Actions Terminal Software or ROM Routines Host User Layer 7 AP Layer 7 Layer 6 SP Layer 6 Layer 5 SP Layer 5 Layer 4 SP/P Layer 4 Layer 3 Host P 3 Layer 2 P 2 Layer 1 P 1 P 3 Protocols Front-end processor P Layer 3 Front-end or switching Node P Layer 2 Front-end Processor P Layer 1 Channel Devices Cluster Control Unit Clarke, R. J (2001) L 909 -02: 47

Web Clients & Servers Source: Yeager & Mc. Grath (1996, 11 -16) Clarke, R. J (2001) L 909 -02: 48

Internet n Internet (=Internetworking) collection of computer networks and to allow interoperability between them n networks can consist of many types of network technologies, protocols, and computers n Several protocols are required for transmitting data across the Internet (TCP/IP) Clarke, R. J (2001) L 909 -02: 49

Internet Protocol n IP manages the transfer of data across physically distinct networks n transfers data into packets within an ‘envelope’ that describing its source and destination n a message is in effect shattered into pieces, packaged as packets in envelopes, and burst transmitted to the destination n IP looks after delivering these packages- one packet at a time! Clarke, R. J (2001) L 909 -02: 50

Internet Transmission Control Protocol n networks are unreliable and IP does not guarantee that all pieces arrive (no notion of a connection) n TCP defines conventions that make sure the pieces arrive in the correct order- by specifying another envelope around the data packets n IP layer moves packets, TCP manages the connection Clarke, R. J (2001) L 909 -02: 51

Internet Other Services & Protocols n the layering or encapsulation which is a characteristic of OSI also works in much the same way with other services supported by the Internet (TCP/IP) n File Transfer Protocol defines the conventions which describe how computers can cooperate in order to copy files from one computer to another on the Internet- it uses TCP/IP to do this Clarke, R. J (2001) L 909 -02: 52

Internet Other Services & Protocols Internet Protocol; Transmission Control Protocol; File Transfer Protocol FTP TCP IP IP Physical Network Clarke, R. J (2001) L 909 -02: 53

Internet Web Services & Protocols n the web is just another internet service! n Hypertext Transfer Protocol (HTTP) is the set of rules for making and fulfilling web requests n however, the web is also designed to encapsulate other protocols including FTP, Gopher, WAIS, telnet and NNTP- we will talk about these services latter Clarke, R. J (2001) L 909 -02: 54

Internet Web Services n works as a client-server- in terms of services not necessarily hardware n differs from other network models (terminal to mainframe; and peer-topeer) because client and server are independent, fully functional computer systems in their own right Clarke, R. J (2001) L 909 -02: 55

Internet Web Services Mainframe & Terminal Typing Printing Client-server Request Reply Peer-to-Peer Send Message email Send Message Clarke, R. J (2001) L 909 -02: 56

Intranets & OA Success of WWW- Open Standards n machines on the Internet are effectively decentralised n an important aspect of the web is that it is a set of open (not proprietary) protocols: n Uniform Resource Locators URLs n Hypertext Transfer Protocol (HTTP) n Hypertext Markup Language (HTML) Clarke, R. J (2001) L 909 -02: 57

Intranets & OA Success of WWW- Specific Issues n web protocols are general enough to be implemented on any computer n web application are the ‘topmost’ layer in the Internet protocol hierarchy n complex processes of transfer of data are ‘hidden’ from the web application developer and user n as a consequence there is a great variety of web applications available Clarke, R. J (2001) L 909 -02: 58

Web Servers & Clients Source: Yeager & Mc. Grath (1996, 11 -16) Web FTP TCP IP IP Physical Network Clarke, R. J (2001) L 909 -02: 59

Summary Clarke, R. J (2001) L 909 -02: 60

Intranets & OA Failure of OA- Proprietary Technologies n OA did not become very important because they were based on proprietary technologies n implies ‘closed’ technologies and markets- ultimately counter-productive! n slow development time, large market lags, small client bases, under utilised technology, increased expense in setup, use, maintenance, upgrade Clarke, R. J (2001) L 909 -02: 61

Intranets & OA Failure of OA- Specific Issues n data sometimes had to be re-enteredproprietary technologies mean that other vendors don’t have the technical information needed to write transfer routines n had to rely on the vendor to keep the technology current- there development team is the only one available to service your needs n incompatibilities- can’t supplement the OA vendors equipment with other vendors products Clarke, R. J (2001) L 909 -02: 62

From OSI to TCP/IP OSI 7: Application Layer 6: Presentation Layer 5: Session Layer 4: Transport Layer 3: Network Layer 2: Data Link Layer 1: Physical Layer 4: Application Layer consists of applications and processes that use the network 3: Host-to-Host Transport Layer provides end-to-end data delivery services 2: Internet Layer defines the datagram and handles the routing of data 1: Network Access Layer consists of routines for accessing physical networks Clarke, R. J (2001) L 909 -02: 63

Next Week n Lecture (L 909 -03): n Office Automation Systems Computer supported Cooperative Work/Groupware n Tutorial (T 909 -02): n Search Engines & Techniques (differs from Tutorial Schedule) Clarke, R. J (2001) L 909 -02: 64