Systems Analysis and Design in a Changing World

Systems Analysis and Design in a Changing World, Fourth Edition Systems Analysis and Design in a Changing World, 4 th Edition 15

15 Learning Objectives u Describe implementation and support activities u Choose an appropriate approach to program development u Describe various types of software tests, and explain how and why each is used u List various approaches to data conversion and system installation, and describe the advantages and disadvantages of each u Describe different types of documentation and the processes by which they are developed and maintained u Describe training and user support requirements for new and operational systems Systems Analysis and Design in a Changing World, 4 th Edition 2

15 Overview u This chapter focuses on activities of implementation and support phases of systems development life cycle (SDLC) u Implementation activities occur before system is turned over to users u Implementation consumes more time and resources than other phases of the SDLC u Support activities occur after system becomes operational and may continue for years Systems Analysis and Design in a Changing World, 4 th Edition 3

Activities of the Implementation and Support Phases Systems Analysis and Design in a Changing World, 4 th Edition 15 4

15 Program Development u Program development is time consuming l One-third of development labor l One-third to one-half of project development schedule Systems Analysis and Design in a Changing World, 4 th Edition 5

15 Order of Implementation u u u Input, process, output (IPO) development order l User interfaces developed early to reduce change l Disadvantage is late implementation of outputs Top-down begins with module at top of structure chart l Always a working version of program l Requires three or more iterations to complete Bottom-up begins with modules at lowest level of structure chart l Many programmers can begin immediately l Requires driver programs to test Systems Analysis and Design in a Changing World, 4 th Edition 6

Structure Chart for the Payroll Program 15 (Figure 15 -3) Systems Analysis and Design in a Changing World, 4 th Edition 7

Package Diagrams for RMO Subsystems Systems Analysis and Design in a Changing World, 4 th Edition 15 8

Package Diagram for a Three-Layer OO Design Systems Analysis and Design in a Changing World, 4 th Edition 15 9

15 Construction and Test Plan Construction and Testing are highly interdependent. Plan Construction and Testing activities early while considering the following: u The development order u The testing order u Data used to test modules, module groups, methods, classes, programs, and subsystems u Acceptance criteria u Relevant personnel assignments (construction and testing) Systems Analysis and Design in a Changing World, 4 th Edition 10

Framework Development 15 u When developing large OO systems, object frameworks or foundation classes Foundation classes typically implemented first l Minimize impact of errors and changes l Reused in many parts of the system and across applications l Assigned to best programmers and thoroughly tested u Later changes to foundation classes might require significant changes to other code that depends on them Systems Analysis and Design in a Changing World, 4 th Edition 11

Team-Based Program Development u Management issues l Organization of programming teams l Task assignment to specific teams or members l Member and team communication and coordination u Variety teams l 15 of different models used for organizing Cooperating peer, chief developer, collaborative specialist Systems Analysis and Design in a Changing World, 4 th Edition 12

Comparison and Summary of Development Team Types (Figure 15 -7) Systems Analysis and Design in a Changing World, 4 th Edition 15 13

15 Source Code Control u Source l code control system (SCCS) Automated tool for tracking source code files and controlling changes to those files u Repository of code and programmer actions l Check out file in read-only mode l Check out file in read/write mode l Check in a modified file Systems Analysis and Design in a Changing World, 4 th Edition 14

15 Versioning u Mechanism to manage systems changes u Complex systems developed, installed, and maintained in series of versions to simplify testing and support l Alpha version – incomplete testing version l Beta version – end-user testing version l Production release version – formally distributed to users or made operational l Maintenance release – bug fixes, small changes Systems Analysis and Design in a Changing World, 4 th Edition 15

15 Quality Assurance u Process of ensuring information system meets minimum quality standards u Determined by users, implementation staff, management u Identification of gaps or inconsistencies in system requirements u QA integrated into project throughout SDLC u Cost of fixing errors rise as project progresses Systems Analysis and Design in a Changing World, 4 th Edition 16

Technical Reviews 15 u Formal or informal reviews of design or construction details by group of developers u Open design and construction process to input from other people u Other programmers can frequently see errors missed by original programmer u Similar to author writing and editor reviewing u Walkthroughs and inspections l Reduce number of errors by factor of 5 to 10 l Reduce testing costs by 50% Systems Analysis and Design in a Changing World, 4 th Edition 17

15 Testing u Process of examining a product to determine if any defects exist u Testing levels are related to specific SDLC u Testing activities spread throughout SDLC phases u Most of testing takes place following software construction and definition of defect standards Systems Analysis and Design in a Changing World, 4 th Edition 18

Generic Model of Software Testing 15 (Figure 15 -12) Systems Analysis and Design in a Changing World, 4 th Edition 19

SDLC Phases and Testing Activities Performed Within Each Phase (Figure 15 -14) Systems Analysis and Design in a Changing World, 4 th Edition 15 20

15 Test Cases u Important part of testing is specifying test cases and test data u. A test case is a formal description of l Starting state l Events to which software responds l Expected response or ending state u Analysis phase documentation is useful in preparing test cases (use-case driven) u Test data is defined to be used with a test case Systems Analysis and Design in a Changing World, 4 th Edition 21

15 Unit Testing u Tests individual modules of code or methods before integrating with other software u Driver module used for testing l Sets values of input parameters l Calls module to be tested and passes input parameters l Accepts return parameters from tested module u Stub testing – test module simulates module not yet developed Systems Analysis and Design in a Changing World, 4 th Edition 22

15 Integration Testing u Tests the behavior of a group of modules or methods u Tests both normal processing and exceptions u Errors can include l Interface incompatibility l Incorrect parameter values l Run-time exceptions l Unexpected state interactions Systems Analysis and Design in a Changing World, 4 th Edition 23

System Testing u Tests 15 the behavior of the entire system u Build and smoke test is performed daily to discover any problems with daily builds l System is completely compiled and linked each day l Battery of tests are run to smoke out problems l Any errors must be from changes made the prior day u Complete system testing also performed before acceptance testing Systems Analysis and Design in a Changing World, 4 th Edition 24

Usability Testing 15 u Usability test is a test to determine whether a module, method, class, subsystem, or system meets user requirements l Focus is usually on ease of use u Performance requirements test checks time-based l Response time l Throughput u Acceptance test is system test performed to determine whether system meets user requirements Systems Analysis and Design in a Changing World, 4 th Edition 25

15 Data Conversion u Data needed at system startup l Files or databases of system being replaced l Manual records l Files or databases of other systems l User feedback during normal system operation u Reuse of existing databases u Reloading u Creating database contents new databases Systems Analysis and Design in a Changing World, 4 th Edition 26

Two Approaches to Reloading Database Content After a Structural Modification Systems Analysis and Design in a Changing World, 4 th Edition 15 27

15 Installation u After development and testing, system must be put into operation u Important planning considerations l Costs of operating both systems in parallel l Detecting and correcting errors in new system l Potentially disrupting the company and IS operations l Training personnel and customers with new procedures Systems Analysis and Design in a Changing World, 4 th Edition 28

15 Direct Installation u New system installed and quickly made operational u Overlapping u Both systems turned off systems concurrent for brief time u Advantage to manage – simplicity and fewer logistics issues u Disadvantage – risk due to no backup Systems Analysis and Design in a Changing World, 4 th Edition 29

15 Parallel Installation u Old and new systems operated together for extended period of time u Advantages – low risk of system failure and continual backup u Disadvantage – cost to operate both systems l Hiring temporary personnel l Acquiring extra space l Increasing managerial and logistical complexity Systems Analysis and Design in a Changing World, 4 th Edition 30

15 Phased Installation u New system installed in series of steps or phases u Each phase adds components to existing system u Advantage – reduces risk because phase failure is less serious than system failure u Disadvantage – multiple phases cause more activities, milestones, and management complexity for entire effort Systems Analysis and Design in a Changing World, 4 th Edition 31

Direct Installation and Cutover 15 (Figure 15 -20) Systems Analysis and Design in a Changing World, 4 th Edition 32

Parallel Installation and Operation 15 (Figure 15 -21) Systems Analysis and Design in a Changing World, 4 th Edition 33

Phased Installation with Direct Cutover and 15 Parallel Operation (Figure 15 -22) Systems Analysis and Design in a Changing World, 4 th Edition 34

15 Personnel Issues u Installing new system places demands on personnel l Demanding schedules l Rapid learning and adaptation l High stress u Planning should anticipate these risks and take measures to mitigate effects u Temporary and contract personnel may be hired during an installation Systems Analysis and Design in a Changing World, 4 th Edition 35

15 Documentation u Automated documentation is standard l Electronic manuals in MS Word or Adobe PDF format l Hyperlinked documents – Web-browser formatted l Online documentation on vendor Web site l Embedded documentation on CD l Electronic system model stored in graphic formats l Tool-specific system models developed with IDEs, DBMSs, and CASE tools Systems Analysis and Design in a Changing World, 4 th Edition 36

15 System Documentation u Descriptions of system functions, architecture, and construction details u Used by maintenance personnel and future developers u Generated as a by-product of development l Includes source code l Includes analysis and design models u Failure to maintain system documentation compromises value of a system Systems Analysis and Design in a Changing World, 4 th Edition 37

Life Cycle Phases and System Documentation Generated in Each Phase 15 (Figure 15 -23) Systems Analysis and Design in a Changing World, 4 th Edition 38

15 User Documentation u Descriptions the system u Used of how to interact with and maintain by end users and system operators u Topics include l Startup and shutdown l Keystrokes, mouse, or command functions to perform specific functions l Program function for specific business procedures l Common errors and correction techniques Systems Analysis and Design in a Changing World, 4 th Edition 39

15 Training and User Support u Without training, user error rates will be high u Training considerations l Frequency and duration of system use l Need to understand system’s business context l Existing computer skills and proficiency l Number of users Systems Analysis and Design in a Changing World, 4 th Edition 40

Typical Activities of End Users and System Operators (Figure 15 -25) Systems Analysis and Design in a Changing World, 4 th Edition 15 41

15 Ongoing Training and User Support u User support covers training and user assistance that occurs after installation l Online documentation and troubleshooting l Resident experts l Help desk l Technical support Systems Analysis and Design in a Changing World, 4 th Edition 42

15 Maintenance and System Enhancement u Modification of software after delivery to correct faults, improve performance, or adapt the product to a changed environment l Tracking modification requests and changes l Implementing changes l Monitoring system performance l Upgrading hardware and software l Updating documentation Systems Analysis and Design in a Changing World, 4 th Edition 43

Submitting Change Requests and Error Reports 15 u Most organizations adopt formal change control procedures to manage change risks l Standard change request forms l Review of requests by change control committee l Extensive planning for design and implementation u Approved changes are added to list of pending changes for budgeting, scheduling, planning, and implementation u. A separate process is used for error correction Systems Analysis and Design in a Changing World, 4 th Edition 44

15 Implementing a Change u Planning for a change includes l Identifying parts of system to change or add l Securing personnel to implement change l Scheduling design and implementation activities l Developing test criteria and test plan for changed system u System documentation is reviewed to determine scope of change Systems Analysis and Design in a Changing World, 4 th Edition 45

A Change Request Example 15 (Figure 15 -26) Systems Analysis and Design in a Changing World, 4 th Edition 46

A Change Review Form (Figure 15 -27) Systems Analysis and Design in a Changing World, 4 th Edition 15 47

15 Upgrading Computing Infrastructure u Infrastructure requires periodic updates l Software maintenance releases l Software version upgrades l Declining system performance u Infrastructure includes computer hardware, system software, networks, DBMSs l Technical, complex, and risky l Outages can impact entire system Systems Analysis and Design in a Changing World, 4 th Edition 48

Summary 15 Implementation activities occur after design and before system is turned over to users u Implementation is complex l Interdependence of programming, quality assurance, hardware and software installation, documentation, and training u Implementation is difficult to manage and is risky l Significant time and resources required l Often affects systems vital to daily operations u Software components constructed to l Minimize development resources needed l Maximize ability to test system and control errors l These goals often conflict: trade-off among resources, time, and desire to correct errors u Data conversion, installation, documentation, and training follow programming and testing u Installed and documented system is prerequisite for complete training u Fully populated database needed to begin operation u Support activities occur after system becomes operational and might continue for years to support user requirements and reduce operational risk Systems Analysis and Design in a Changing World, 4 th Edition 49 u