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