20 July Management Information Systems 9. Components of Workgroup Information Systems by Asst. Prof. Wichai Bunchua
20 July 01 Components of Workgroup Information Systems Multiuser system alternative Commmunications standards Hardware Programs Data Procedures People
20 July 01 Multiuser System Alternatives Centralized systems Distributed systems Local Area Network (LAN) Hybrid systems Backbone networks Linled LANs Wide Area Network (WAN)
20 July 01 Centralized Systems Advantages Centralized control Established vendors and technology Low technicalrisk High capacity for TPS
20 July 01 Centralized Systems (cont.) Disadvantages High cost Highly trained personnel required for development and to a lesser extent for operations No local computing Vulnerable to loss of the single CPU
20 July 01 Distributed Systems Advantages Low start-up costs Tailorable, scalable Local computing possible Reliability of many computers
20 July 01 Distributed Systems (cont.) Disadvantages Lack of centralized control Multiplevendor problems Rapidly changing technology Performance cap
20 July 01 Hybrid Systems Advantages Greatest capacity Hybrid control Most tailorable and scalable
20 July 01 Hybrid Systems (cont.) Disadvantages Coplicated Expensive Difficult to set up High technical risk Some technical problems unsolved, to date
20 July 01 Communications Standards Data communication Protocols : Sets of rules for conducting data communications Systems Network Architecture (SNA) by IBM Digital Network Architecture (DNA) by Digital Equipment Corporation Open Systems Interconnection (OSI) model by ISO
20 July 01 The OSI Model Seven layers of the OSI model 1. Physical layer 2. Data-link layer 3. Network layer 4. Transport layer 5. Session layer 6. Presentation layer 7. Application layer
20 July 01 LAN Protocols Two typical protocols CSMA/CD (IEEE 802.3) Token ring (IEEE 802.5)
20 July 01 Hardware: LAN topology LAN topologies Bus topology Ring Topology Star topology
20 July 01 LAN Communication Media and Tranmission Three types of communication, or trnsmission, media, or cables used on a LAN Twisted pairs Coaxial cable Optical fiber Two strtegies or styles of transmission Baseband Broadband
20 July 01 Data-Link Protocols Two most common data-link protocols Contention protocol Token passing
20 July 01 Contention Protocols Contention (IEEE 802.3) Ethernet Nodes listen to line Transmit when line is idle Stop when collisions occur Almost always implemented on bus
20 July 01 Token Passing Protocol Token passing (IEEE bus; IEEE ring) Continuous stream of data on network Token indicates whether node can transmit Addresses in token indicate destination address of message Message removes by nodes that generate them
20 July 01 Programs System programs Network OS Two most popular Netware 386 from Novell LAN manager from Microsoft Network request processing Distributed database processing
20 July 01 Distributed Database Processing Two architectures of database processing on a LAN-based system Resource-sharing Client/server In client/server, the DBMS is separated into two parts The client DBMS The server DBMS
20 July 01 Application Programs in a Distributed System Database application programs Horizontal application products vertical application products
20 July 01 Data Nonconcurrent data sharing Concurrent data sharing Record-level sharing File-level sharing
20 July 01 Procedures User procedures for normal processing Operations procedures for normal processing User Procedures for failure recovery Operation procedures for failure recovery
20 July 01 People Workgroup operations people Users Operators Network LAN manager Data adminis people