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Lecture Chapter 16: Making the system operational
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Lecture "Chapter 16: Making the system operational" provides students with the knowledge: Program development, order of implementation, structure chart for a payroll system, system flowchart for a payroll system, construction and test plan,...Invite you to consult.
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Nội dung Text: Lecture Chapter 16: Making the system operational
- 16 16 Learning Objectives Chapter 16: Describe implementation and support activities Making the System Operational Choose an appropriate approach to program development Systems Analysis and Design in a Changing World, 3rd Edition Describe various types of software tests and explain how and why each is used Systems Analysis and Design in a Changing World, 3rd Edition 2 16 16 Learning Objectives (continued) Overview List various approaches to data conversion and This chapter focuses on activities of system installation and describe the advantages implementation and support phases of systems and disadvantages of each development life cycle (SDLC) Implementation activities occur before system is Describe different types of documentation and turned over to users the processes by which they are developed and maintained Implementation consumes more time and resources than earlier phases of the SDLC Describe training and user support requirements for new and operational systems Support activities occur after system becomes operational and may continue for years Systems Analysis and Design in a Changing World, 3rd Edition 3 Systems Analysis and Design in a Changing World, 3rd Edition 4 16 16 Activities of the Implementation Program Development and Support Phases Program development is time consuming One-third of development labor One-third to one-half of project development schedule Programming and testing considerations: Required resources Managerial complexity System quality Systems Analysis and Design in a Changing World, 3rd Edition 5 Systems Analysis and Design in a Changing World, 3rd Edition 6
- 16 16 Order of Implementation Order of Implementation (continued) Input, process, output (IPO) development order Top-down and bottom-up order from traditional Based on data flow through system structured design and structured programming Simplifies testing Top-down begins with top structure chart module User interfaces developed early to reduce change Always a working version of program Disadvantage is late implementation of outputs Requires three or more iterations to complete Structured design – IPO order based on system Bottom-up begins with modules at lowest level of flowchart and structure chart structure chart OO design – IPO order in package diagrams Many programmers can begin immediately Requires driver programs to test Systems Analysis and Design in a Changing World, 3rd Edition 7 Systems Analysis and Design in a Changing World, 3rd Edition 8 16 16 System Flowchart for a Payroll System Structure Chart for a Payroll System Systems Analysis and Design in a Changing World, 3rd Edition 9 Systems Analysis and Design in a Changing World, 3rd Edition 10 16 16 Package Diagrams for RMO Subsystems Package Diagram for Three-Layer OO Systems Analysis and Design in a Changing World, 3rd Edition 11 Systems Analysis and Design in a Changing World, 3rd Edition 12
- 16 16 Construction and Test Plan Framework Development Development order When developing large OO systems, object frameworks or foundation classes are often Testing order constructed Foundation classes typically implemented first Data used to test modules, module groups, methods, classes, programs, and subsystems Minimizes impact of errors and changes Reused in many parts of the system and across Acceptance criteria applications Relevant personnel assignments (construction Assigned to best programmers and thoroughly and testing) tested Systems Analysis and Design in a Changing World, 3rd Edition 13 Systems Analysis and Design in a Changing World, 3rd Edition 14 16 16 Comparison and Summary of Team-Based Program Development Development Team Types Management Issues Organization of programming teams Task assignment to specific teams or members Member and team communication and coordination Variety of different models used for organization Systems Analysis and Design in a Changing World, 3rd Edition 15 Systems Analysis and Design in a Changing World, 3rd Edition 16 16 16 Source Code Control Versioning Source code control system (SCCS) Mechanism to manage systems changes Automated tool for tracking source code files and Complex systems developed, installed, and controlling changes to those files maintained in series of versions to simplify testing and support Repository of code and programmer actions Alpha Version – incomplete testing version Check out file in read-only mode Beta Version – end user testing version Check out file in read/write mode Production Release Version – formally distributed to users or made operational Check in a modified file Maintenance Release – bug fixes, small changes Systems Analysis and Design in a Changing World, 3rd Edition 17 Systems Analysis and Design in a Changing World, 3rd Edition 18
- 16 16 Description of Versions for RMO Quality Assurance Process of ensuring information system meets minimum quality standards Determined by users, implementation staff, management Identification of gaps or inconsistencies in systems requirements QA integrated into project throughout SDLC Cost of fixing errors rise as project progresses Systems Analysis and Design in a Changing World, 3rd Edition 19 Systems Analysis and Design in a Changing World, 3rd Edition 20 16 16 Technical Reviews Testing Opens design and construction process to input Process of examining a product to determine if from other people any defects exist Other programmers can frequently see errors missed by original programmer Testing levels are related to specific SDLC phases Similar to author writing and editor reviewing Walkthroughs and inspections Testing activities spread throughout SDLC Reduce number of errors by factor of 5 to 10 Reduce testing costs by 50% Most of testing takes place following software construction and definition of defect standards Systems Analysis and Design in a Changing World, 3rd Edition 21 Systems Analysis and Design in a Changing World, 3rd Edition 22 16 16 Correspondence Between SDLC Phases Generic Model of Software Testing and Various Types of Testing Systems Analysis and Design in a Changing World, 3rd Edition 23 Systems Analysis and Design in a Changing World, 3rd Edition 24
- 16 16 SDLC Phases and Testing Activities Test Cases Performed Within Each Phase Important part of testing is specifying test cases and data Test cases specify one or more events to which software must respond Starting state Events to which software responds Expected response or ending state Analysis phase documentation is useful in preparing test cases Systems Analysis and Design in a Changing World, 3rd Edition 25 Systems Analysis and Design in a Changing World, 3rd Edition 26 16 16 Unit Testing Integration Testing Testing individual modules of code or methods Tests the behavior of a group of modules or before integration with other software methods Driver module used for testing Test both normal processing and exceptions Sets values of input parameters Errors can include: Calls module to be tested and passes input Interface incompatibility parameters Incorrect parameter values Accepts return parameters from tested module Run-time exceptions Stub testing – test module simulates module not Unexpected state interactions yet developed Systems Analysis and Design in a Changing World, 3rd Edition 27 Systems Analysis and Design in a Changing World, 3rd Edition 28 16 16 System Testing Data Conversion Tests the behavior of the entire system Data needed at system startup Files or databases of system being replaced Build and smoke test is performed daily to Manual records discover any problems with daily builds Files or databases of other systems Performance test checks time-based requirements User feedback during normal system operation Reuse of existing databases Acceptance test is performed to determine whether system meets user requirements Reloading database contents Creating new databases Systems Analysis and Design in a Changing World, 3rd Edition 29 Systems Analysis and Design in a Changing World, 3rd Edition 30
- 16 16 Two Approaches to Reloading Database A Complex Data-Conversion Example Content After a Structural Modification Systems Analysis and Design in a Changing World, 3rd Edition 31 Systems Analysis and Design in a Changing World, 3rd Edition 32 16 16 Installation Direct Installation After development and testing, system must be New system installed and quickly made put into operation operational Important planning considerations Overlapping systems turned off Costs of operating both systems in parallel Both systems concurrent for brief time Detecting and correcting errors in new system Potentially disrupting the company and IS Advantage: simplicity and fewer logistics issues operations to manage Training personnel and customers with new procedures Disadvantage: risk due to no backup Systems Analysis and Design in a Changing World, 3rd Edition 33 Systems Analysis and Design in a Changing World, 3rd Edition 34 16 16 Parallel Installation Phased Installation Old and new systems operated together for New system installed in series of steps or phases extended period of time Each phase adds components to existing system Advantages: low risk of system failure and continually backup Advantage: reduced risk because phase failure is Disadvantage: cost to operate both systems less serious than system failure Hiring temporary personnel Acquiring extra space Disadvantage: multiple phases causes more activities, milestones, and management Increasing managerial and logistical complexity complexity for entire effort Systems Analysis and Design in a Changing World, 3rd Edition 35 Systems Analysis and Design in a Changing World, 3rd Edition 36
- 16 16 Direct Installation and Cutover Parallel Installation and Operation Systems Analysis and Design in a Changing World, 3rd Edition 37 Systems Analysis and Design in a Changing World, 3rd Edition 38 16 16 Phased Installation with Direct Personnel Issues Cutover and Parallel Operation Installing new system places demands on personnel Demanding schedules Rapid learning and adaptation High stress Planning should anticipate these risks and take measures to mitigate effects Temporary and contract personnel may be hired during an installation Systems Analysis and Design in a Changing World, 3rd Edition 39 Systems Analysis and Design in a Changing World, 3rd Edition 40 16 16 Documentation System Documentation Automated documentation is standard Descriptions of system functions, architecture, Electronic manuals stored in MS Word or Adobe and construction details Hyperlinked documents: Web browser formatted Used by maintenance personnel and future developers On-line documentation on vendor Web site Generated as a byproduct of development Embedded documentation on CD Includes source code Electronic system model stored in graphic formats Includes analysis and design models Tool-specific system models developed with IDEs, DBMSs, and CASE tools Failure to maintain system documentation compromises value of a system Systems Analysis and Design in a Changing World, 3rd Edition 41 Systems Analysis and Design in a Changing World, 3rd Edition 42
- 16 16 Lifecycle Phases and System User Documentation Documentation Generated in Each Phase Descriptions of how to interact with and maintain the system Used by end users and system operators Topics covered include: Startup and shutdown Keystrokes, mouse, or command functions to perform specific functions Program function for specific business procedures Common errors and correction techniques Systems Analysis and Design in a Changing World, 3rd Edition 43 Systems Analysis and Design in a Changing World, 3rd Edition 44 16 16 Typical Activities of End Users and Training and User Support Systems Operators Without training, user error rates will be high Training considerations Frequency and duration of system use Need to understand system’s business context Existing computer skills and proficiency Number of users Systems Analysis and Design in a Changing World, 3rd Edition 45 Systems Analysis and Design in a Changing World, 3rd Edition 46 16 16 Ongoing Training and User Support Maintenance and System Enhancement User support covers training and user assistance Modification of software after delivery to correct that occurs after installation faults, improve performance, or adapt the product to a changed environment On-line documentation and troubleshooting Tracking modification requests and changes Resident experts Implementing changes Monitoring system performance Help desk Upgrading hardware/software Technical support Updating documentation Systems Analysis and Design in a Changing World, 3rd Edition 47 Systems Analysis and Design in a Changing World, 3rd Edition 48
- 16 16 Submitting Change Requests and Error Implementing a Change Reports Most organizations adopt formal change control Planning for a change includes: procedures to manage change risks Identify parts of system to change or addition Standard change request forms Secure personnel to implement change Review of requests by change control committee Extensive planning for design and implementation Schedule design and implementation activities Approved changes are added to list of pending Develop test criteria and testing plan for changed changes for budgeting, scheduling, planning, and system implementation System documentation is reviewed to determine A separate process is used for error correction scope of change Systems Analysis and Design in a Changing World, 3rd Edition 49 Systems Analysis and Design in a Changing World, 3rd Edition 50 16 16 Upgrading Computing Infrastructure Summary Infrastructure requires periodic updates Implementation activities occur after design and before system is turned over to users Software maintenance releases Implementation is complex Software version upgrades Interdependence of programming, quality Declining system performance assurance, hardware and software installation, Infrastructure includes computer hardware, documentation and training system software, networks, DBMSs Implementation is difficult to manage Technical, complex, and risky Activities must be properly sequenced Outages can impact entire system Progress must be continually monitored Systems Analysis and Design in a Changing World, 3rd Edition 51 Systems Analysis and Design in a Changing World, 3rd Edition 52 16 16 Summary (continued) Summary (continued) Implementation is risky Data conversion, installation, documentation, and Significant time and resources required training follow programming and testing Often affects systems vital to daily operations Installed and documented system is prerequisite for complete training Software components constructed in order to: Fully populated database needed to begin Minimize development resources needed operation Maximize ability to test system and control errors Support activities occur after system becomes These goals often conflict: trade-off among operational and may continue for years to support resources, time, and desire to correct errors user requirements and reduce operational risk Systems Analysis and Design in a Changing World, 3rd Edition 53 Systems Analysis and Design in a Changing World, 3rd Edition 54
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