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Chapter 3

Chapter 3. Database Architectures and the Web. Multi-User DBMS Architectures. Teleprocessing File-server Client-server. Teleprocessing. Traditional architecture Single mainframe with number of terminals attached. File-Server. File-server connected to several workstations across network

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Chapter 3

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  1. Chapter 3 Database Architectures and the Web

  2. Multi-User DBMS Architectures Teleprocessing File-server Client-server

  3. Teleprocessing Traditional architecture Single mainframe with number of terminals attached

  4. File-Server File-server connected to several workstations across network Database resides on file-server DBMS and applications run on each workstation Disadvantages: Significant network traffic Copy of DBMS on each workstation Concurrency, recovery and integrity control more complex

  5. File-Server Architecture

  6. Traditional Two-Tier Client-Server Client (tier 1) manages user interface and runs applications Server (tier 2) holds database and DBMS Advantages: wider access to existing databases increased performance possible reduction in hardware costs reduction in communication costs increased consistency

  7. Traditional Two-Tier Client-Server

  8. Traditional Two-Tier Client-Server

  9. Three-Tier Client-Server Problems preventing true scalability in 2-tier: ‘Fat’ client, requiring considerable resources on client’s computer to run effectively Significant client side administration overhead 1995 - three layers proposed

  10. Three-Tier Client-Server Advantages: ‘Thin’ client Requires less expensive hardware Application maintenance centralized Easier to modify/replace one tier without affecting others Separation business logic from database functions → easier to implement load balancing Maps naturally to Web environment

  11. Three-Tier Client-Server

  12. Transaction Processing Monitors (TPM) Program that controls data transfer between clients and servers in order to provide a consistent environment, particularly for Online Transaction Processing (OLTP).

  13. TPM • Transaction processing monitor • Controls data transfer between clients/servers • Provides a consistent environment, particularly for online transaction processing (OLTP) • Significant advantages • Transaction routing • Managing distributed transactions • Load balancing • Funneling • Increased reliability

  14. TPM as middle tier of 3-tier client-server

  15. Multi-user DBMS Architectures • Teleprocessing • Traditional architecture for multi-user systems • One computer with a single central processing unit (CPU) and a number of terminals • Put a huge burden on the central computer • Downsizing • Replacing expensive mainframe computers with more cost-effective networks of personal computers

  16. Multi-user DBMS Architectures • File-server architecture • Processing distributed about network • Disadvantages: • Large amount of network traffic • Full copy of DBMS required on each workstation • Concurrency, recovery, and integrity control are complex

  17. Multi-user DBMS Architectures • Traditional two-tier client–server architecture • Client process requires some resource • Server provides the resource • Basic separation of four main components of business application • Typical interaction between client and server

  18. Summary of client–server functions

  19. Multi-user DBMS Architectures • Three-tier client–server architecture • User interface layer • Business logic and data processing layer • DBMS • Many advantages over traditional two-tier or single-tier designs

  20. Multi-user DBMS Architectures • N-tier architectures • Three-tier architecture can be expanded to n tiers • Application servers • Hosts an application programming interface (API) to expose business logic and business processes for use by other applications

  21. Multi-user DBMS Architectures • Middleware • Software that mediates with other software • Communication among disparate applications • Six main types • Asynchronous Remote Procedure Call (RPC) • Synchronous RPC • Publish/Subscribe • Message-Oriented middleware (MOM) • Object-request broker (ORB) • SQL-oriented data access

  22. Web Services and Service-Oriented Architectures • Web service • Software system that supports interoperable machine-to-machine interaction over network • No user interface • Examples of Web services • Microsoft Virtual Earth Web service • Uses widely accepted technologies and standards

  23. Web Services and Service-Oriented Architectures • Service-Oriented Architectures (SOA) • Architecture for building applications that implement business processes as sets of services • Some principles built upon: • Loose coupling • Reusability • Composability

  24. Traditional vs. SOA Architecture

  25. Distributed DBMSs • Distributed database • Logically interrelated collection of shared data physically (single database) distributed over network • Distributed DBMS • Software system that permits management of distributed database • Distribution transparent to users

  26. Distributed DBMSs • Characteristics of DDBMS • Collection of logically related shared data • Data split into fragments • Fragments may be replicated • Fragments/replicas allocated to sites • Sites linked by communications network • Data at each site controlled by DBMS • DMBS handles local apps autonomously • Each DBMS in one or more global app

  27. Distributed DBMSs • Distributed processing • Centralized database that can be accessed over computer network • System consists of data physically distributed across number of sites in network

  28. Data Warehousing • Data warehouse • Consolidated/integrated view of corporate data • Drawn from disparate operational data sources • Range of end-user access tools capable of supporting simple to highly complex queries to support decision making • Subject-oriented, integrated, time-variant, and nonvolatile

  29. Typical Architecture of a Data Warehouse

  30. Components of a DBMS • Major components of a DBMS: • Query processor • Database manager (DM) • File manager • DML preprocessor • DDL compiler • Catalog manager

  31. Components of a DBMS • Major software components for database manager • Authorization control • Command processor • Integrity checker • Query optimizer • Transaction manager • Scheduler • Recovery manager • Buffer manager

  32. Oracle Architecture • Oracle’s logical database structure • Tablespaces • Schemas • Data blocks • Extents/segments

  33. Relationship between an Oracle Database,Tablespaces, and Datafiles

  34. Oracle Architecture • Oracle’s physical database structure • Datafiles • Redo log files • Control files • The Oracle instance • Oracle processes and shared memory required to access information in the database

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