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Chapter 12

Chapter 12. Client/Server Systems Database Systems: Design, Implementation, and Management, Fifth Edition, Rob and Coronel. In this chapter, you will learn:. What client/server computing is What the advantages of using client/server systems are How client/server systems evolved

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Chapter 12

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  1. Chapter 12 Client/Server Systems Database Systems: Design, Implementation, and Management, Fifth Edition, Rob and Coronel

  2. In this chapter, you will learn: • What client/server computing is • What the advantages of using client/server systems are • How client/server systems evolved • About client/server systems components and how they interact • What effect the client/server system has on the DBMS • How client/server systems might be introduced into an organization • What factors affect the implementation of client/server systems Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  3. Client/Server Computing • Computing model for the development of computerized systems • Client requests specific service • Server provides requested service • Reside on same or different computers Figure 12.1 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  4. Client/Server Computing (con’t.) • Key to client server power is where request processing takes place • Extent of sharing processing • Thin client • Thin server • Fat client • Fat server • Classification • 2-tier • 3-tier Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  5. Forces that Drive Client/Server Trend • Changing business environment • Growing need for enterprise data access • Demand for end-user productivity gains based on efficient use of data • Technological advances • Growing cost/performance advantages Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  6. Evolution of Computing Environment Figure 12.2 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  7. Mainframe vs. Client/Server Systems Table 12.1 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  8. Managerial Expectations of Client/Server Systems • Client/Server efficiency functions • Platform independent development • Optimized distribution of processing activities among different platforms • User friendly and cost effective techniques, methodologies, and specialized tools • Observations • Tool, not end goal • Not answer to all data management problems • Has own set of management problems Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  9. MIS Expectations of Client/Server Benefits • Reduced development and implementation costs • Reduced development time and increased programmer productivity • Extended system life cycle through scalability and portability • Reduced system operational cost • Change of MIS function from development to end-user support • Enhanced information deployment Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  10. Organizational Expectations of Client/Server Benefits • Flexibility and adaptability • Improved employee productivity • Improved company work flow and way to reengineer business operations • New opportunities for competitive advantages • Increased customer service satisfaction Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  11. Components of Client/Server Architecture • Client • Front-end application • Server • Back-end application • Communications middleware • Communications layer Figure 12.3 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  12. Example Client/Server Architecture Figure 12.4 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  13. Client/Server Principles • Hardware independence • Software independence • Operating systems • Network systems • Applications • Open access to services • Process distribution • Process autonomy • Maximization of local resources • Scalability and flexibility • Interoperability and integration • Standards Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  14. Client Components Figure 12.5 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  15. Server Components • File services • Print services • Fax services • Communications services • Database services • Transaction services • Miscellaneous services Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  16. Server Components Figure 12.6 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  17. Typical Characteristics of Server Hardware • Fast CPU • Fault-tolerant capabilities • Dual power • Standby power • Error checking and correcting memory • RAID • Expandability of CPU, memory, disk, and peripherals • Bus support for multiple add-on boards • Multiple communications options Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  18. Server Process Benefits • Location independence • Resource optimization • Scalability • Interoperability and integration Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  19. Database Middleware • Network independence • Front-end application accesses data without regard to network protocols • Database server independence • Generic SQL to access different database servers • Isolates programmer from SQL dialect differences Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  20. Communications Middleware • Two levels • Physical level • Client and server computers • Logical level • Client and server processes • Interprocess communication (ICP) protocols Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  21. OSI Network Reference Model Table 12.2 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  22. Information Flow through OSI Model Figure 12.7 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  23. Network Protocols • Transmission Control Protocol/Internet Protocol (TCP/IP) • Internetwork Packet Exchange/ Sequenced Packet Exchange (IPX/SPX) • Network Basic Input Output System (NetBIOS) • Application Program to Program Communications (APPC) Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  24. Interactions between Middleware Components Figure 12.10 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  25. Competing Standards • Client operating systems • Microsoft Windows • OS/2, Apple Mac OS, Unix, Linux • Client graphical user interfaces • Microsoft Windows • OS/2 Presentation Manager, Macintosh, UNIX • Server operating systems and network protocols • Database servers: Unix, OS/2, Windows NT Server/2000 Server • Printer and file servers: Novell Netware • LAN protocols: TCP/IP, IPX/SPX, NetBIOS • Middleware • ODBC, IDAPI, DRDA, Q+E Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  26. Client/Server DBMS Functions • Transparent data access to multiple, heterogeneous clients • Allow client requests to the database server over network • Process client data requests at local server • Send only SQL results to clients over network Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  27. Application Logic Components Figure 12.14 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  28. Client/Server Architectural Styles • Two Key Questions • How is the division made? • Where should the results of division be placed? • Five Functional Logic Components • Presentation logic • I/O processing logic • Application of business logic • Data management logic • Data manipulation logic Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  29. Application Functional Components Figure 12.15 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  30. Functional Logic Splitting Figure 12.16 Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  31. Client/Server versus Traditional DP • Proprietary to open systems • Maintenance-oriented coding to analysis, design, and service • Data collection to data deployment • Centralized to distributed style • Vertical, inflexible to horizontal, flexible organizational style • Differences in IS components Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

  32. Client/Server Implementation Issues • Management Issues • Communications infrastructure • Applications • Controlling escalating and hidden costs • People and cultural changes • Multiple vendor relationships • Development tool acquisition • Determination if client/server approach is correct Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

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