Chapter 8

1. Chapter 8 PHASE 3: SYSTEMS DESIGN System Architecture

2. Chapter Objectives • Provide a checklist of issues to consider when selecting a system architecture • Describe servers, server-based processing, clients, and client-based processing • Explain client/server architecture, including tiers, cost-benefit issues, and performance considerations • Describe the impact of the Internet on system architecture

3. Chapter Objectives • Explain the difference between online and batch processing • Define network topology, and provide examples of hierarchical, star, bus, and ring network models • Explain network protocols and licensing issues

4. Chapter Objectives • Explain system management tools and techniques, including performance measurement, fault management, backup, and disaster recovery • Describe the systems design specification and explain the contents of each section

5. Introduction • An effective system combines elements into an architecture, or design, that is flexible, cost-effective, technically sound, and able to support the information needs of the business • System architecture translates the logical design of an information system into a physical structure that includes hardware, software, network support, processing methods, and security

6. System Architecture Checklist • A systems analyst must approach system architecture with an overall checklist • Enterprise resource planning (ERP) • Initial and total cost of ownership (TCO) • Scalability • Web integration • Legacy system interface requirements • System security • Processing options

7. System Architecture Checklist • Enterprise Resource Planning (ERP) • The objective of ERP is to establish a company-wide strategy for using IT resources • Describes environment – platform • Supply chain management • Initial Cost and TCO • During the final design stage, you make decisions that will have a major impact on the initial costs and TCO for the new system • You should review all previous cost estimates

8. System Architecture Checklist • Initial Cost and TCO • Ask questions like the following • Is in-house development still best choice? • Is specific package still best choice? • New outsourcing available? • New technology available? • Answers might affect the initial cost and TCO for the proposed system

9. System Architecture Checklist • Scalability • Scalability, also called extensibility • Especially important in implementing systems that are volume-related, such as transaction processing systems • Web Integration • An information system includes application programs, also called applications • Web-centric

10. System Architecture Checklist • Legacy System Interface Requirements • The new system might have to interface with one or more legacy systems • Interfacing a new system with legacy systems involves analysis of data formats and compatibility • The analyst must know if the new application eventually will replace the legacy system

11. System Architecture Checklist • Processing Options • Online or Batch • 24/7 • Backup and Recovery

12. System Architecture Checklist • Security Issues • Security is a concern at every stage of system development • The systems analyst must consider security issues that relate to system design specifications and determine how the company will address them • Web-based systems introduce additional security concerns

13. Planning the Architecture Every information system involves 3 main functions: • Data Storage and Access Methods • Application Programs • Interface The 3 functions may be performed on a … • Server OR • Client OR • Divided between Server and Client

14. Client/Server Architecture • Today’s interconnected world requires an information architecture that spans the entire enterprise • Whether you are dealing with a departmental network or a multinational corporation, as a systems analyst you will work with a distributed computing strategy called client/server architecture

15. Client/Server Architecture Overview • Client/server architecture

16. Client/Server Architecture Client/Server Design Styles • Many forms • Database Server • Transaction Server • Web Server

17. Client/Server Architecture Types of Clients: Fat and Thin • Fat client - Thick client • Thin client Comparison: Thin  better performance Thick  more processing

18. Client/Server Architecture Client/Server Tiers • Two-tier design • Three-tier design • Middle layer

19. Client/Server Architecture Middleware -Cost-Benefit Issues • Scale the system http://www.centene.com/investors/annual_reports • Transfer applications • Improve response times

20. Client/Server Architecture Client/Server Performance Issues • Separation of server-based data and networked clients • Separates applications and data • Client contacts server only when necessary • Distributed Database Management System (DDBMS)

21. Internet-Based Architecture • The Internet has had an enormous impact on system architecture • To support this trend, systems analysts must suggest e-commerce strategies that apply available technology and meet their company’s business requirements

22. Internet-Based Architecture • Developing E-Commerce Solutions In-House • If you decide to proceed with an in-house solution, you must have an overall plan to help achieve your goals • An in-house solution usually requires a greater initial investment, but provides more flexibility for a company that must adapt quickly in a dynamic e-commerce environment

23. Internet-Based Architecture • Packaged Solutions and E-Commerce Service Providers • Turnkey systems • Application service provider (ASP) • Does lower initial cost outweigh disadvantage of reduced flexibility?

24. Internet-Based Architecture • Corporate Portals • A portal is an entrance to a multifunction Web site • A corporate portal can provide access for customers, employees, suppliers, and the public

25. Network Models The OSI Reference Model – consists of 7 layers • Application layer • Presentation layer • Session layer • Transport layer • Network layer • Data link layer • Physical layer

26. Network Models Network Topology • Hierarchical network

27. Network Models Network Topology • Star network

28. Network Models Network Topology • Bus network

29. Network Models Network Topology • Ring network

30. Network Models Network Topology • Other topologies http://compnetworking.about.com/od/networkdesign/a/topologies.htm

31. Network Models Network Protocols and Licensing Issues • The network must use a protocol • A popular network protocol is Transmission Control Protocol/Internet Protocol (TCP/IP) • A familiar example of a TCP/IP protocol is the file transfer protocol (FTP)

32. Systems Design Completion System Design Specification • Baseline • Contents vary depending on company standards • You do not have to turn this in

33. Systems Design Completion User Approval of … • Interface design • Report and menu designs • Data entry screens • Source documents • Other

34. Systems Design Completion Presentations • Systems analysts, programmers, technical staff • Department managers and users • Company management • Objective: Obtain management’s approval/support

35. Chapter Summary • The analyst must consider enterprise resource planning, initial cost and TCO, scalability, Web integration, legacy interface requirements, security, and processing options • System security is an important concern • An architecture requires servers and clients • Compared to file server designs, client/server systems are more scalable and flexible

36. Chapter Summary • Networks allow the sharing of hardware, software, and data resources in order to reduce expenses and provide more capability to users • The way a network is configured is called the network topology • The system design specification presents the complete systems design for an information system Any questions?