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Implementation

Implementation. Week 14 CMIS570. SDLC. Project Planning. Analysis. Design. Implementation ***. Support. Delineating IV and V. Implementation Activities that occur before the system is turned over to its users Maintenance/Support

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Implementation

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  1. Implementation Week 14 CMIS570

  2. SDLC Project Planning Analysis Design Implementation *** Support

  3. Delineating IV and V • Implementation • Activities that occur before the system is turned over to its users • Maintenance/Support • Activities that occur after the system becomes operational

  4. Managing Implementation • Analogy to building a house • Architecture (analysis/design) • Construction (implementation) • Large number of people • Myriad interdependent activities • Program development • Quality assurance • Physical installation • Documentation • Training

  5. Managing Implementation • MAJOR ISSUES: • Order of program development • Source code control & versioning • Quality assurance and testing • Installation • Documentation and training

  6. Order of Program Development • IPO (1-Input, 2-Process, 3-Output) • Advantages: • Simplifies testing • Input programs can be used to enter test data • User interfaces are developed early • Allows for early user evaluation of interfaces • Head start on user documentation and training materials • Disadvantages: • Late implementation of outputs • Outputs are helpful in testing process modules

  7. Order of Program Development • TOP-DOWN • Create “stub” versions of subordinate modules • Primary advantage: • Always a working version of a program • Primary disadvantage: • Use of programming personnel at beginning can be inefficient

  8. Order of Program Development • BOTTOM-UP • Create “driver” versions of calling programs • Advantages: • Efficient use of programmers from the get-go • Lower-level modules often most complex, so this allows more time for development and testing of them • Disadvantages: • Writing a large number of “driver” programs • Adds complexity to developing and testing process

  9. Order of Program Development • Is just one part of the overall development and test plan • Development and testing go hand-in-hand • Plan should be created before beginning program development, covering: • Development order • Testing order • Generation of test data • Test cases • Acceptance criteria • Personnel and other resource needs

  10. Source Code Control and Versioning • SCCS • Automated tool for tracking source code files and controlling changes to those files • Allows only 1 programmer to check out a file to update • Prevents multiple programmers from updating same file at same time

  11. Example of SCCS

  12. Versioning • For development, testing, and maintenance of large complex systems • Used in development: • Alpha version(s) • Test version that is incomplete but ready for some level of rigorous testing • Lifetime is usually short (days or weeks)

  13. Versioning • Used in testing: • Beta version(s) • Test version that is stable enough to be tested by end users (to do real work) • Produced after one or more alpha versions have been “perfected” • Typically evaluated over period of weeks or months

  14. Versioning • Used in production/maintenance: • Production version (or release) • Formally distributed to users • Considered the final product • Multiple production versions are used to add features and fix bugs discovered after releasing original production version

  15. Source Code Control and Versioning • Versioning control is a part of most sophisticated SCCS’s • New programs and system versions move along this general landscape: Development and Unit Testing Integration and Systems Testing Production

  16. QA and Testing • Quality Assurance (QA) • Process of ensuring that an IS meets minimal quality standards • QA during Analysis phase: • Identifying gaps or inconsistencies in system requirements • QA during Design phase: • Satisfying stated requirements and making appropriate design decisions • QA during Implementation phase: • Applying QA tools to program design and coding, and then Testing

  17. QA and Testing • QA tools used throughout SDLC: • Technical review • Formal or informal review of analysis, design, or development details by a group of analysts, developers, and/or users • Walkthough is one type of technical review • Two or more people review the accuracy and completeness of a model or program • Developer of model or program leads the walkthrough, describing assumptions, key decisions, and operation

  18. QA and Testing • QA tools used throughout SDLC: • Inspection • More formal version of a walkthrough • Participants review and analyze materials before they meet as a group • Participants play specific roles: • Presenter – usually the developer, summarizes the material being inspected • Critics – describe errors and concerns found • Recorder – records all errors/concerns and the agreed-upon solution strategies

  19. QA and Testing • Walkthroughs and inspections have been found to: • Reduce number of errors that reach testing by a factor of 5 to 10 • Reduce testing costs by approx. 50% • Goal is to catch as many errors as possible using these QA tools – prior to Testing

  20. QA and Testing • TESTING • Process of examining a product to determine what defects it contains • TESTING in Implementation phase: • Unit • Testing individual programs or modules • Integration • Testing groups of programs/modules • Systems • Testing an entire system (including interfaces between application components)

  21. QA and Testing • Test planning is not easy! • Should utilize QA tools (to ensure quality of test plan!) • Walkthrough test plans • Inspect test cases • Test plans and cases should be retained after Implementation • WHY?

  22. QA and Testing • UNIT Testing • Testing of individual modules before they are integrated with other modules • Examines internal design of program • The goal: Every instruction should be executed at least once • Path testing: Design test cases that focus on small segments of code; aim to exercise a high percentage of the internal paths • Called “white box” testing

  23. QA and Testing • INTEGRATION Testing • Testing of a group of modules • “Black box” testing – done without knowledge of programs’ internal design • Can elucidate problems such as: • Interface incompatibility • Incorrect data type or length being passed • Incorrect parameter values passed • Unexpected state interactions • States of 2 or more modules combine to create an unexpected situation

  24. QA and Testing • SYSTEM Testing • Test the entire application system • First performed by developers or test personnel • After passing system tests by developers and test personnel: • ACCEPTANCE testing • Performed by users • To determine whether system fulfills user requirements • Uses a beta version • Usually treated as a very formal activity

  25. QA and Testing • A common recommendation: “Separate Testing From Development” • Why? • Humans tend not to find own mistakes • But recommend keeping unit and integration testing with programmer • Why? • After unit and integration testing, transfer test responsibility to dedicated test group

  26. Installation • Four approaches: • Direct (big-bang) installation • Parallel installation • Single location • Phased installation

  27. Direct (Big-Bang) Installation

  28. Parallel Installation

  29. Single Location Installation

  30. Phased Installation

  31. Installation • Each approach has strengths and weaknesses related to: • Cost • Complexity • Risk • Which way is best?

  32. Documentation • Documentation • System Documentation • Descriptions of system functions, architecture, and development details • Used by maintenance personnel and developers of future systems • User Documentation • For end users: Descriptions of how to interact with and utilize the system • For system operators: Descriptions of how to maintain the system and keep it operable

  33. Documentation • System Documentation includes: • DFD, ERD, Process Models • System Flow Chart, Structure Chart • Function Hierarchy Diagrams, CRUD Matrices • Database Schema code (SQL statements) • Program source code • Test data and cases

  34. Documentation • User Documentation • Is task-based • Describes functionalities • Contains how-to’s • Keystrokes, mouse, and commands to perform specific functions • Contains FAQ’s • Explains error messages • Contains an index and “getting started” section

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