Class 3 Distributed Systems

1. Asper School of Business 9.613 Using Information Technology Part-Time MBA, December 2001 Instructor: Bob Travica Class 3 Distributed Systems 9.613 Using Information Technology

2. Outline • Key systems terminology • Concept of distributed systems • Types of distributed systems • Rationale for Distributing Systems • Conditions for Distributed Systems • Distributed Systems Architectures • Client-Server (C/S) Architecture • Trends in Distributed Architectures 9.613 Using Information Technology

3. Key Systems Terminology (Computer-Based IS) • Data component • - content and structure of data, storage (hardware), • retrieval (software) • - concern of database developers and system analysts • Process component • - data processing/transformation & movement • “programs” for processing & network software & hardware, • functionality • concern of programmers and system analysts • User interface (part of software - screens the user sees) More 9.613 Using Information Technology

4. Key Systems Terminology Process Data User interface User More 9.613 Using Information Technology

5. Key Systems Terminology Organizational Goals Work Domain Needs System Data, Processes & User Interface System Requirements System Design More 9.613 Using Information Technology

6. Key Systems Terminology • IS Architecture (ISA) – an overall design of organizational • information resources (specific systems & their design, • IT types & standards, data models, networks, spatial layout) • Cognate concepts (more specific than ISA): • Systems Design (specific systems - above) • IT Infrastructure(fundamental enterprise-wide IT; necessary for • applications to run; e.g., enterprise-wide databases, operating systems) • Information Architecture (just data component) • Networks Architecture(communication protocols, topology, layout) 9.613 Using Information Technology

7. Distributed System (DS) Concept • Opposite to centralized system • In DS, processing and/or data decentralized to certain degree Mainframe with dumb terminals Interconnected stand-alone systems Client-Server Systems high low Centralization Continuum • Key role of networking • Importance of standards for connectivity 9.613 Using Information Technology

8. Why distribute systems? • To support organizational requirements (efficiency, • effectiveness) • Technological reasons (efficiency, effectiveness in • data, input, processing, transfer, storage) • To support distributed organizational forms • (country/region, division, process, teams; • virtual organizations consisted of different firms) 9.613 Using Information Technology

9. Conditions for Distributed Systems • Spatial dispersion of organization • Different data/information needs • (FF franchises; regional division of production vs. • sales – DDB example) • Different data/information & processing needs (MN Corp.- • accounting, marketing, production—input, quality control) • Culture supporting decentralization (ex: PARC, change • at IBM) Fast food franchiser Multinational Corp. Manufacturing low System Distribution high 9.613 Using Information Technology

10. Distributed Systems Architectures • Interconnected Stand-Alone Systems (departmental • processing and data management with communication • links between departments; opposite to HBH) • Peer LAN-Based System (equal distribution of processing and data management among peer computers) • Client-Server Architecture Models (next slide) More 9.613 Using Information Technology

11. Client-Server (C/S) Architecture • C/S systems distributes either data or processing • or both between a machine that requests a service (client) • and a machine that provides a service (server). • User interface is typically the client’s responsibility. More 9.613 Using Information Technology

12. Request Client Server Service Client Middleware Server Client-Server (C/S) Architecture • C/S systems distributes either data or processing • or both between a machine that requests a service (client) • and a machine that provides a service (server). • User interface is typically the client’s responsibility. More 9.613 Using Information Technology

13. Client-Server Models • Models of C/S architecture determined by different • distribution patterns (Figure 5-8; e.g., S manages data • and shares processing with C, or S just manages data wile • all processing on C) • Try a bit different terms, taking server perspective • (“remote” refers to client): • Distributed presentation (user interface) • Remote Presentation • Distributed Processing • Remote Processing • Distributed Data Management 9.613 Using Information Technology

14. IT Infrastructure • The fundamental IT capability (company-wide network and • databases, large-scale computing facilities + essential technical • and management solutions – ex: distributed vs. centralized arch. ) • Similar to other infrastructures (city, transportation…; • hard/technical + soft/social & cognitive components – policies, • professions, jobs, knowledge) • Serves as the basis for applications/services; • Complex, costly, long-term, promised & intangible benefits 9.613 Using Information Technology

15. Trends in Distributed Architectures • Pervasive computing (e.g., Jini from Sun Microsystems; • any network used for connecting clients, • servers and consumer devices; Java objects instead of • device drivers) • Peer-to-Peer (e.g., Napster - distributed data, • Groove - distributed data; Internet used as network) • Application Service Providers – distributed processing 9.613 Using Information Technology