Systems Analysis & Design Sixth Edition Chapter 9

Systems Analysis & Design Sixth Edition Chapter 9

Phase Description Systems Implementation is the fourth of five phases in the systems development life cycle (SDLC) Includes application development, testing, documentation, training, data conversion, system changeover, and postimplementation evaluation of the results 2

Chapter Objectives Explain the importance of software quality assurance and software engineering Describe the application development process Draw a structure chart showing top-down design, modular design, cohesion, and coupling Explain the coding process and how code is generated Explain unit testing, integration testing, and system testing 3

Chapter Objectives Differentiate between program, system, operations, and user documentation List the main steps in system installation and evaluation Develop an overall training plan with specific objectives for each group of participants, compare in-house and outside training providers, and describe effective training techniques 4

Chapter Objectives Describe the data conversion process Identify and describe changeover methods Explain post-implementation evaluation Describe the final report to management 5

Introduction The system design specification serves as a blueprint for constructing the new system The initial task is application development Before a changeover can occur, the system must be tested and documented carefully, users must be trained, and existing data must be converted A formal evaluation of the results takes place as part of a final report to management 6

Software Quality Assurance Quality assurance Software Engineering – Software Engineering Institute (SEI) – Capability Maturity Model (CMM) – Capability Maturity Model Integration (CMMI) – Process improvement – CMMI tracks an organization's processes, using five maturity layers 7

Software Quality Assurance International Organization for Standardization (ISO) – Many firms seek assurance that software systems will meet rigid quality standards – In 1991, ISO established a set of guidelines called ISO 9000-3 – ISO requires a specific development plan, which outlines a step-by-step process for transforming user requirements into a finished product 8

Overview of Application Development Application development Objective is to translate the logical design into program and code modules that will function properly Creation of the System Design – The tasks involved in system design produced an overall design and a plan for physical implementation 9

Overview of Application Development Application Development Steps – Module – Start by reviewing documentation from prior SDLC phases and creating a set of program designs – After the design is created, coding can begin 10

Overview of Application Development Project Management – Even a modest-sized project might have hundreds or even thousands of modules – Important to set realistic schedules, meet project deadlines, control costs, and maintain quality – Should use project management tools and techniques 11

Structured Application Development Top-down approach Partitioning Modular design Must proceed carefully, with constant input from programmers and IT management to achieve a sound, well-integrated structure Must ensure that integration capability is built into each design and thoroughly tested 12

Structured Application Development Structure Charts – Structure charts show the program modules and the relationships among them – Control module – Subordinate modules 13

Structured Application Development Structure Charts – Module Library module – Data Couple – Control Couple Flag A module uses a flag to signal a specific condition or action to another module 14

Structured Application Development Structure Charts – Condition A condition line indicates that a control module determines which subordinate modules will be invoked, depending on a specific condition – Loop A loop indicates that one or more modules are repeated 15

Structured Application Development Cohesion and Coupling – If you need to make a module more cohesive, you can split it into separate units, each of which performs a single function – Loosely coupled – Tightly coupled – Status flag 16

Structured Application Development Structure Chart Examples 17

Structured Application Development Drawing a Structure Chart – Step 1: Review the DFDs – Step 2: Identify Modules and Relationships – Step 3: Add Couples, Loops, and Conditions – Step 4: Analyze the Structure Chart and the Data Dictionary 18

Structured Application Development Other Structured Development Tools – Program Flowcharts – Pseudocode 19

Object-Oriented Application Development Object-Oriented Application Development Compared to Structured Development – When implementing an object-oriented design, relationships between objects already exist – The application's structure is represented by the object model itself – Attributes – Methods 20

Object-Oriented Application Development Implementation of Object-Oriented Design – Programmer makes necessary revisions and updates to class diagrams, sequence diagrams, state transition diagrams, and activity diagrams – Main objective is to translate object methods into program code modules and determine what event or message will trigger the execution of each module 21

Coding Coding Programming Environments – Each IT department has its own programming environment and standards – Integrated development environments (IDEs) Generating Code – Can generate editable program code directly from macros, keystrokes, or mouse actions 22

Testing the System After coding, a programmer must test each program to make sure that it functions correctly Syntax errors Desk checking – Logic errors Structured walkthrough, or code review Design walkthrough 23

Testing the System Unit Testing – Test data – Programmers must test programs that interact with other programs and files individually – Stub testing – Regardless of who creates the test plan, the project manager or a designated analyst also reviews the final test results 24

Testing the System Integration Testing – Integration testing, or link testing – Testing the programs independently does not guarantee that the data passed between them is correct – A testing sequence should not move to the integration stage unless it has performed properly in all unit tests 25

Testing the System System Testing – Major objectives: Perform a final test of all programs Verify that the system will handle all input data properly, both valid and invalid Ensure that the IT staff has the documentation and instructions needed to operate the system properly and that backup and restart capabilities of the system are adequate 26

Testing the System System Testing – Major objectives: Demonstrate that users can interact with the system successfully Verify that all system components are integrated properly and that actual processing situations will be handled correctly Confirm that the information system can handle predicted volumes of data in a timely and efficient manner 27

Testing the System System Testing – Acceptance tests – You should regard thorough testing as a cost-effective means of providing a quality product – If conflicting views exist, management will decide whether or not to install the system after a full discussion of the options 28

Documentation Documentation Program Documentation System Documentation Operations Documentation User Documentation – Online documentation 29

Management Approval After system testing is complete, you present the results to management If system testing produced no technical, economical, or operational problems, management determines a schedule for system installation and evaluation 30

System Installation and Evaluation Remaining steps in systems implementation: – Prepare a separate operational and test environment – Provide training for users, managers, and IT staff – Perform data conversion and system changeover – Carry out post-implementation evaluation of the system – Present a final report to management 31

Operational and Test Environments The environment for the actual system operation is called the operational environment or production environment The environment that analysts and programmers use to develop and maintain programs is called the test environment A separate test environment is necessary to maintain system security and integrity and protect the operational environment 32

Operational and Test Environments 33

Training Training Plan – The first step is to identify who should receive training and what training is needed – The three main groups for training are users, managers, and IT staff – You must determine how the company will provide training 34

Training Vendor Training – If the system includes the purchase of software or hardware, then vendorsupplied training is one of the features you should include in the RFPs (requests for proposal) and RFQs (requests for quotation) that you send to potential vendors – Often gives the best return on your training dollars 35

Training Outside Training Resources – Many training consultants, institutes, and firms are available that provide either standardized or customized training packages – You can contact a training provider and obtain references from clients – Center for the Application of Information Technologies (CAIT) 36

Training In-House Training – The IT staff and user departments often share responsibility – When developing a training program, you should keep the following guidelines in mind: Train people in groups, with separate training programs for distinct groups Select the most effective place to conduct the training Provide for learning by hearing, seeing, and doing Prepare effective training materials, including interactive tutorials Tutorial 37

Training In-House Training – When developing a training program, you should keep the following guidelines in mind: Rely on previous trainees Train-the-trainer strategy – When Training is complete, many organizations conduct a full-scale test, or simulation 38

Data Conversion Data Conversion Strategies – The old system might be capable of exporting data in an acceptable format for the new system or in a standard format such as ASCII or ODBC – If a standard format is not available, you must develop a program to extract the data and convert it – Often requires additional data items, which might require manual entry 39

Data Conversion Data Conversion Security and Controls – You must ensure that all system control measures are in place and operational to protect data from unauthorized access and to help prevent erroneous input – Some errors will occur – It is essential that the new system be loaded with accurate, error-free data 40

System Changeover Direct Cutover – Involves more risk than other changeover methods – Companies often choose the direct cutover method for implementing commercial software packages – Cyclical information systems usually are converted using the direct cutover method at the beginning of a quarter, calendar year, or fiscal year 41

System Changeover Parallel Operation – Easier to verify that the new system is working properly under parallel operation than under direct cutover – Running both systems might place a burden on the operating environment and cause processing delay – Is not practical if the old and new systems are incompatible technically – Also is inappropriate when the two systems perform different functions 42

System Changeover Pilot Operation – The group that uses the new system first is called the pilot site – The old system continues to operate for the entire organization – After the system proves successful at the pilot site, it is implemented in the rest of the organization, usually using the direct cutover method – Is a combination of parallel operation and direct cutover methods 43

System Changeover Phased Operation – You give a part of the system to all users – The risk of errors or failures is limited to the implemented module only – Is less expensive than full parallel operation – Is not possible, however, if the system cannot be separated easily into logical modules or segments 44

Post-Implementation Tasks Post-Implementation Evaluation – Includes feedback for the following areas: Accuracy, completeness, and timeliness of information system output User satisfaction System reliability and maintainability Adequacy of system controls and security measures Hardware efficiency and platform performance 45

Post-Implementation Tasks Post-Implementation Evaluation – Includes feedback for the following areas: Effectiveness of database implementation Performance of the IT team Completeness and quality of documentation Quality and effectiveness of training Accuracy of cost-benefit estimates and development schedules 46

Post-Implementation Tasks Post-Implementation Evaluation – When evaluating a system, you should: Interview members of management and key users Observe users and computer operations personnel actually working with the new information system Read all documentation and training materials Examine all source documents, output reports, and screen displays Use questionnaires to gather information and opinions form a large number of users Analyze maintenance and help desk logs 47

Post-Implementation Tasks Post-Implementation Evaluation – Users can forget details of the developmental effort if too much time elapses – Pressure to finish the project sooner usually results in an earlier evaluation in order to allow the IT department to move on to other tasks – Ideally, conducting a postimplementation evaluation should be standard practice for all information systems projects 48

Post-Implementation Tasks Final Report to Management – Your report should include the following: Final versions of all system documentation Planned modifications and enhancements to the system that have been identified Recap of all systems development costs and schedules A comparison of actual costs and schedules to the original estimates Post-implementation evaluation, if it has been performed – Marks the end of systems development work 49

Chapter Summary Develop a training program Data conversion often is necessary when installing a new information system System changeover is the process of putting the new system into operation A post-implementation evaluation assesses and reports on the quality of the new system and the work done by the project team 50

Chapter Summary The final report to management includes the final system documentation, describes any future system enhancements that already have been identified, and details the project costs Chapter 9 complete 51