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Chapter 2

Chapter 2. The database development process. Information Systems Architecture. A conceptual blueprint or plan that expresses the desired future structure for the information systems in an organization. Architecture example. Data validation and retention. Integrated data warehouse

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Chapter 2

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  1. Chapter 2 The database development process

  2. Information Systems Architecture A conceptual blueprint or plan that expresses the desired future structure for the information systems in an organization.

  3. Architecture example Data validation and retention Integrated data warehouse Access analysis and presentation tools Information delivery system CIM Business Operations EDI Customers & Suppliers External Events External database access Dialogue Decision makers Customers, Suppliers

  4. A more sophisticated example...

  5. Information Systems Architecture • Key components: • data • processes which manipulate data • network which transports data • peoplewho perform processes and send and receive data • events and points in timewhen processes are performed • reasonsfor events and rules which govern data processing

  6. Information Engineering An Information Systems Architecture is developed by IS planners following a particular methodology such as Information Engineering.

  7. Information Engineering • Data-oriented methodology • Uses top-down planning in which specific information systems are deduced from a broad understanding of organization’s information needs, rather than relying on specific user information requests • Offers perspective on relationship of information systems to business objectives

  8. Top-Down Planning: A methodology that attempts to gain a broad understanding of the information system needs of the entire organization Bottom-Up Planning: A methodology that identifies and defines IS development projects based upon solving operational business problems or taking advantage of business opportunities Top-Down vs. Bottom-Up

  9. The big picture... Information engineering • Information systems planning • Identify strategic planning factors (goals, CSFs, problem areas) • IT vision • Identify corporate planning objectives • Information system architecture • Develop enterprise model • Systems analysis • Systems design • implementation

  10. Project Initiation & Planning Analysis Logical Design Physical Design Implementation Maintenance Systems Development Life Cycle Project Identification & Selection

  11. Database SDLC SDLC Database Development Activities Identify Project Enterprise Modeling Initiate and Plan Conceptual Data Modeling Analyze Logical DB Design Logical Design Physical DB Design/Creation Physical Design DB Implementation Implementation DB Maintenance Maintenance

  12. Planning Matrixes • Show interrelationships between objects. Among the possibilities: • Location-to-Function • Unit-to-Function • Information System-to-Data Entity • Supporting Function-to-Data Entity • Information System-to-Objective

  13. Business Function-to-Data Entity Planning Matrix

  14. Information System-to-Objective Planning Matrix

  15. Functional Decomposition

  16. Enterprise Data Modeling The first step in database development, in which the scope and general contents of organizational databases are specified.

  17. Enterprise Data Model • A model which includes: • overall range of organizational databases • general contents of organizational databases • Built as part of IS planning for the organization and not the design of a particular database • One part of an organization’s overall information systems architecture (ISA)

  18. Conceptual Database Modeling • Determine user requirements • Determine business rules • Build conceptual data model • outcome is an entity-relationship diagram or similar communicationtool • population of repository Enterprise Modeling Conceptual Data Modeling Logical DB Design Physical DB Design/Creation DB Implementation DB Maintenance

  19. Logical Database Design • Select logical database model • commit to a database alternative • Map Entity-Relationship Diagrams • Normalize data structures • Specify business rules Enterprise Modeling Conceptual Data Modeling Logical DB Design Physical DB Design/Creation DB Implementation DB Maintenance

  20. Physical Database Design • Select DBMS • Select storage devices • Determine access methods • Design files and indexes • Determine database distribution • Specify update strategies Enterprise Modeling Conceptual Data Modeling Logical DB Design Physical DB Design/Creation DB Implementation DB Maintenance

  21. Database implementation • Code and test database processing programs • Complete documentation • Install database and convert data Enterprise Modeling Conceptual Data Modeling Logical DB Design Physical DB Design/Creation DB Implementation DB Maintenance

  22. Database Maintenance • Analyze database and applications to ensure evolving information requirements are being met • Tune database for improved performance • Fix errors • Provide data recovery when needed Enterprise Modeling Conceptual Data Modeling Logical DB Design Physical DB Design/Creation DB Implementation DB Maintenance

  23. Documentation • most formal development methodologies are documentation based • helps managers monitor progress and quality of project • facilitates communication between team members • includes models • various stages are not complete until documentation is accepted

  24. Some Keys to Success... • accurate requirements definition • commitment • effective change management • manageable size • champion

  25. So …

  26. Three Schema Architecture for Database Development • Conceptual Schema • Analysis project phase • External Schema • Analysis and Logical Design phases • (subset of conceptual schema) • Internal Schema • Physical Design phase

  27. 3-schema architecture

  28. Conceptual Schema • Describes the logical structure of the entiredatabase • Independent of a specific DBMS • Avoids details of physical design • Stated in • ERDs • metadata

  29. External Schema • Also called a user view • Specifications includescreen formats, report formats, transaction definitions

  30. Physical Schema • Describes physical structure of entire database • Specifies how data from a conceptual schema are stored in secondary memory • Sometimes called internal schema • Specifications include physical file and data structures, storage organization, and index structures

  31. 3-schema development process

  32. Rapid application development • design methodology which speeds systems delivery through a combination of speedy design iterations, data modeling, user/developer teamwork, and automated development tools. • encompasses a set of techniques that can be used to build complex, strategic, and mission-critical applications in months rather than years

  33. RAD

  34. The RAD lifecycle • requirements planning • conduct joint requirement planning workshop • design • conduct JAD workshop • construction • members of team monitor evolution, system is prototyped • cutover • installation

  35. Within the time box... Requirements planning User design construction phase build and evolve prototype User review time box request for change Evaluate system cutover

  36. Barriers to overcome... • poor training/ tools • reluctance to leave old methods behind • mindset that RAD is not adequate for large-scale systems development • speedy delivery does not mean low quality • “creeping functionality”

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