Transcript Networking
3. Introduction to ICTs Today’s FIVE IT assets Security Network Programming & Data management Interface Web system NETWORKING Definition • Process of inter-connecting two or more computers so that users can – Communicate – Share resources – Overcome shortfalls of standalone computers • Speed up computation • Distribute processing tasks and/or data Advantages • Hardware resource sharing – E.g. Processor, space, computer peripherals • • • • • Database sharing Software sharing Communication between users Decentralised data processing Security of data – Backing up with duplicate storage hence guarding against accidental loss Types of networks Wide Area Network (WAN) Metropolitan Area Network (MAN) Local Area Network (LAN) • Computers distributed over wide geographical area • Can be public (government) • Can be private (e.g. SWIFT (society for worldwide interbank financial transactions, INDONET, SBINET) • Microwave/ satellite transmission/ international telephone network • Lower speeds of data transmission than MAN • Consists of single nodes, clusters and/or LANs • Covers wider area than LAN but smaller than WAN, covering a city • High data transmission speeds over metropolitan distances • System of interconnected microcomputers in a limited geographical area like a building or campus • High sharing of network resources (common communication link) • Central storage facility • Network operating system to manage network resources and microcomputers • Low error rate as network contains built-in components for detecting system errors • Private ownership by user • Not subject to regulation by public telecommunications authority • Devices on network can operate independent of network • Can support heavy traffic over sort distances compared to a telecommunications network Advantages of WAN • Allows access to databases at remote sites – Caution: increased security risks • Failure of remote node (i.e. computer on network) means remaining nodes can still communicate • If network fails, local node can still access its own database • Daily data kept locally results in quick access • Local office can maintain data more easily whilst corporate office can access data as needed • Upgrade of storage capacity can be done without affecting data transfer between nodes. • Communication governed by public telecommunications authority (with strict rules of adherence) as opposed to relative freedom of the LAN Types of LAN • Client/server – Server: • Is a computer that manages shared resources as well communication between nodes • Has large processor, RAM and secondary storage capacity – Client: • Computers on the network that request for services from the server • Peer-to-peer – Each computer with equal status and functioning – Independent communication of computers without using server – Less expensive than client/server – Performance slower than client/server Network topologies • Topology – The way computers are physically connected on a network • Network architecture – Specifications of the components that can be connected to a network • Types of topologies – Star, Ring, Bus, Hybrid LAN Components • Workstation – • File server – • Manages communication in network and shared resources, including file access and shared software Application software – • Coaxial or fibre optic cables (with high data transfer speeds) for networking computers Network operating system – • Hub that does not use power or active devices on network connecting up to 4 nodes covering maximum distance of 300ft. LAN cable – • Powered distribution point/ electronic device to which multiple computers are attached using twisted pair cables Connects up to 8 nodes covering maximum distance of 2000ft Passive hub – • Facilitates communication between two networks with different technologies Network interface unit/ network card/ network adapter Active hub – – • Powerful computer with special-purpose software to serve files to other workstations on the network Gateway – • • User workstations and server workstations Software that is meant for a multiple-user environment: shared copies Protocols Protocols • Sets of rules and procedures to control data transmission between a computer and other devices • Must be the same for two devices that want to communicate • Include TCP, FTP, UTP etc. • Send and interpret data • Provide continuous feedback during data transmission • Engage recovery procedures when errors occur • Provide safe termination for all communicating devices PROGRAMMING LANGUAGES Differentiating Programming Languages Language Features Advantages Disadvantages Machine language Denoted using 1’s and 0’s High speed -very efficient in computer circuits Translation free Tedious Machine dependent Error prone Complex language Assembly language Used mnemonic codes Easier than machine language Provision of program statement and syntax error listings Considerable time writing Require translation Good memory required High level languages Similar to English language - shortened statements Use compilers to check syntax then convert to target language Interpreter translates statement and executes it immediately before reading next statement (e.g. LISP) Readability Platform independent Easy debugging Easier to maintain Low development cost Easy documentation Poor control on hardware Less efficient Evolution of languages LANGUAGE DEVELOPERs YEAR DEVELOPED BASIC Prof. John Kemeny and Thomas Kurtz, USA 1964 FORTRAN IBM, USA 1957 PASCAL Prof. Niklaus Wirth, Switzerland 1971 ADA Honeywell Computer Company, USA 1980 C Bell Telephone Laboratories, USA COBOL JAVA VISUAL BASIC C++ PYTHON 1960s Sun Systems 1994 DATA/INFORMATION MANAGEMENT Databases Definition: database system Set of logically connect data files that have common access methods between them Importance Data treated as an organisational resource offer following advantages: data independence, data sharing, data integrity, data availability Components Database files, DBMS, host-level language interface system, natural language interface, application programs, data dictionary, report generator Users Application programmers, end-users and database administrators Models/Architectures (1) Hierarchical, (2) Network, (3) Relational Disadvantages Higher data processing costs, increased hardware and software costs, increases security and integrity risks Exploring & harnessing information Data mining and Data warehousing THE INTERFACE Human Computer Interaction (HCI) DEFINITION A set of programs that facilitates the interaction between the user and the hardware VARIATIONS Command-driven and graphical user interface (GUI) EVOLUTION Require input from mouse, speech, images, cameras, touch-screens Output graphics and videos, sound, etc. Require concurrent triggers from various input devices MODERN CONCERNS Growth in user diversity, holographic input/output SMART COMPUTING HUMAN FACTOR GOALS – DESIGN INTERFACES THAT (1) Minimise learning time (2) Maximise speed of performance (3) Minimise rate of user errors (4) Maximise user satisfaction (5) Maximise user’s retention of knowledge over time WEB-BASED AND MULTIMEDIA SYSTEMS Web-based and Multimedia Systems “a picture is worth more than a thousand words” • Pushed by and used for – – – – Growth in GUI Market economy (e-commerce) Social networking Globalisation effects of the Internet and World Wide Web – Learning, Entertainment – Diversities of users Conclusion • Five major technologies – Drive one another – Consider user’s needs or demands first – Are now moving in the age of Smart Computing • Food for thought How will they evolve??