The Architecture of Distributed Systems

1. The Architecture of Distributed Systems Enterprise wide computing, networking and the desktop revolution

2. IT Architecture • Hardware and software • Tools to access, package, deliver, & communicate information • Standards, models, & control framework • Configuration integrating components • What is the difference between an IT Architecture and an IT Infrastructure?

3. IT Architecture and Infrastructure • Architecture is overall blue print of how systems “fit” together • IS community has lost credibility b/c of failure in this area. • Infrastructure is a particular implementation of IT architecture with basic capabilities shared across business units. • ??Why is an overall IT architecture important?

4. Views of IT Infrastructure • Utility • necessary and unavoidable service, often viewed as administrative expense. • Firms with this view tend to offer fewest infrastructure services • focus on lowering costs and not reengineering processes.

5. Views of IT Infrastructure • Dependent • Tied to specific business programs in plan (ex. Improve service quality) • infrastructure planning included in current business plan • measured in short-term benefits • minimum requirement for implementing BPR

6. Views of IT Infrastructure • Enabling • continuous re-alignment of IT infrastructure with firm strategy. • Long term strategy • infrastructure provides basis for flexibility, rapid adaptation of future strategies • costs viewed as business investments • networks used extensively in business processes • increased up front costs

7. Focus on IT Infrastructure • Corp. IS departments moving from hw/sw to application/infrastructure focus • IS depts. in business of maintaining IT infrastructure • s/w development reduced to modifying packages for/by end users • CIOs starting to prefer CTO title • Why is IS dept. focus on infrastr. a recipe for obsolescence or extinction of IS depts.?

8. IT Architecture • Applications • IT-enabled process redesign • Productivity applications • Competitive advantage • Structure & controls • Standards, policies and procedures • Information models • System development methodologies

9. IT Architecture • User interface • GUI • IO devices • Tools & packages • Presentation & reporting • Analysis & modeling • Groupware • Personal productivity • DSS

10. IT Architecture • Information Management • Hardware • OS • DBMS • Document management systems • Information retrieval • Communication management • Networks • Gateways • Email & file transfer

11. IT Architecture Evolution • Mainframes with “dumb” terminals • download/upload data • run mainframe programs (usu. batch) • little local processing • Micros moved it to desktop • Network computing model • centralized model with network replacing m/f

12. Central Processing Unit Control Unit ALU Input Devices Output Devices Primary Storage Unit Secondary Storage Devices The Computer System Concept

13. Changes in Computer Architecture 1930 1950 1957 1965 1975 firstgeneration secondgeneration thirdgeneration fourthgeneration prototype vacuumtube transistor integratedcircut mechanicalrelay microprocessor

14. Pentium Chip

15. A Microprocessor control unit arithmeticlogic unit 128K temporary memory systemclock input/outputcircuitry

17. Performance vs. Price

18. Computer Classifications Mainframes Midrange Computers Microcomputers

19. Servers Client Systems Networked Computer Systems Host Systems/ Superservers

20. How distributed are your systems? • Where is the processing of data done? • Distributed processing • How are the processors and other devices interconnected? • Processor connectivity • Where is the information stored? • Distributed databases • What rules or standards are used? • Protocols, transmission standards, etc.

21. Distributed System Frameworks • Organizational View • Corporate HQ • Regional HQ • Plant or Site • Department • Work Group • Individual

22. Types of Distributed Systems • Host-based hierarchical systems

23. Host-based Hierarchy

24. Types of Distributed Systems • Host-based hierarchical systems • Decentralized Stand-Alone Systems

25. Decentralized Stand-alone System

26. Types of Distributed Systems • Host-based hierarchical systems • Decentralized Stand-Alone Systems • Peer-Peer LAN-Based Systems

27. Peer-to-Peer LAN-based System

28. Types of Distributed Systems • Host-based hierarchical systems • Decentralized Stand-Alone Systems • Peer-Peer LAN-Based Systems • Hybrid Enterprise-Wide Systems

30. Types of Distributed Systems • Host-based hierarchical systems • Decentralized Stand-Alone Systems • Peer-Peer LAN-Based Systems • Hybrid Enterprise-Wide Systems • Client/Server Systems

31. Some Common Client/Server Definitions • “A network that uses smart nodes instead of dumb terminals” • “Ability to distribute the workload” • “Client manages the human interface; server manages the files”

32. Client/Server Basic Architecture Request Sent Request Answered Client Server

33. Client/Server Basic Architecture Server Client Server Becomes Client Mainframe

35. Types of Servers • Database Servers • Resource Servers • Application Servers • Computation Servers

36. Client/Server Computing (from Gartner Group [5])

37. Benefits of Client/Server Computing • Easy Database Access • Downsizing Computer Resources • Shared Hardware & Software Resources • Increased Management Control • Remove “Islands of Automation” • Scalable Architecture

38. Benefits of Client/Server Computing • Faster Application Development • Reduced Application Development Backlog • Increased Application Performance

39. Barriers to Client/Server Computing • Implementation Costs • Equipment • Systems Integration • Retraining IS Personnel • MIS Culture • Immature Technology • Lack of Management Tools

40. Barriers to Client/Server Computing • Threat to Stable Operations • Data Security • Complexity • Investment Payback

41. Types of Distributed Systems • Host-based hierarchical systems • Decentralized Stand-Alone Systems • Peer-Peer LAN-Based Systems • Hybrid Enterprise-Wide Systems • Client/Server Systems • Network-Centric Systems • NC machines (see table 6-3 for summary costs)

42. Network-Centric System

43. Enterprise IT Architecture • Enterprise architecture framework • Account for different roles in complex projects • planner, owner, designer, builder, sub, user • Account for components of complex systems • data models, functional models, network models, people, time frames, underlying goals/motivations • usually requires huge investment and corporate wide initiative

44. Assimilating New IT • Phased Assimilation Model • Technology Identification • Learning and Adaptation • Rationalization/Management Control • Maturity/Technology Transfer

45. Types of IT Investments • strategic system investments • Informational system investments • EIS, DSS, management control, etc. • Transactional system investments • support repetitive, operational processes • Infrastructure investments • provide the base foundation of IT capabilities

46. Types of IT Investments

47. Conclusions • Distributed systems have dominated IT development of 1990’s architectures • C/S type may be moving to hybrid NC type • No one predicted the rise of the Internet • Internet2? • Complexity and speed of distributed systems will increase