The System Development Life Cycle

1. The System Development Life Cycle By : Careene McCallum-Rodney Systems Analysis and Design, Kendall and Kendall,

2. Introduction • Analysts take a systematic approach to the analysis and design of information systems. This is embodied in what we refer to as the System Development Life Cycle (SDLC). • Systems are best developed through the use of a specific cycle of analyst and user activities. Systems Analysis and Design, Kendall and Kendall,

3. Seven Phases of the SDLC • Identifying problems, opportunities, and objectives. • Determining information requirements • Analyzing system needs • Designing the recommended system. • Developing documenting software. • Testing and maintaining the system. • Implementing and evaluating the system. Systems Analysis and Design, Kendall and Kendall,

4. Phase 1: Identifying Problems, Opportunities and Objectives IDENTIFYING PROBLEMS • This stage is critical to the success of the rest of the project, since no one wants to waste subsequent time addressing the wrong problem. • The analyst will need to look honestly at what is occurring in a business. So that problems can be pinpointed. These problems will be brought up by others (such as organizational members), and they are the reason the analyst was called in. Systems Analysis and Design, Kendall and Kendall,

5. Phase 1: Identifying Problems, Opportunities and Objectives IDENTIFYING OPPORTUNITIES • Opportunities are situations that the analyst believes can be improved upon through the use of computerized information systems. • Seizing opportunities may allow the business to gain a competitive edge or set industry standards. Systems Analysis and Design, Kendall and Kendall,

6. Phase 1: Identifying Problems, Opportunities and Objectives IDENTIFYING OBJECTIVES • The analyst will have to first identify what the business is trying to do. • Then the analyst will be able to see if some aspect of information system application can help the business reach its objectives by addressing specific problems or opportunities. Systems Analysis and Design, Kendall and Kendall,

7. Phase 1: Identifying Problems, Opportunities and Objectives CONCLUSION • The people involved in this phase are the users, analysts, and systems managers coordinating the project. • Activities involved in this phase involves • Interviewing user management • Summarizing the knowledge obtained • Estimating the scope of the project • Documenting the results • The output of this phase is a feasibility report containing a problem definition and summarizing the objectives. Systems Analysis and Design, Kendall and Kendall,

8. Phase 2: Determining Information Requirements • This phase focuses on determining the information requirement for the particular user involved. • Some of the tools used to define information requirements in a business are: • Sampling and investigating hard data. • Interviewing • Questionnaires • Observing decision makers’ behaviour and office environment • Prototyping (this will include some but not all features, one that, if successful, will eventually be part of the larger, final system that is delivered) • Analysts are trying to understand what information the users need to perform their jobs. Systems Analysis and Design, Kendall and Kendall,

9. Phase 2: Determining Information Requirements • This kind of study may have a different purpose and is typically carried out by a specialist called an information analyst. • People involved in this phase are: • Analysts • Users (operational managers and operations workers) • The systems analyst needs to know the details of current function • The who (the people who are involved) • The what (The business activities) • Where (the environment in which the work takes place) • When (the timing), and • How (how the current procedures are performed) Systems Analysis and Design, Kendall and Kendall,

10. Phase 2: Determining Information Requirements • The analyst must ask why the business uses the current system. There may be good reasons for using the current method, and these should be considered when designing any system. • On completion of this phase, the analyst must understand: • How the business functions • Have complete information on the people, goals, data, and procedures involved. Systems Analysis and Design, Kendall and Kendall,

11. Phase 3: Analyzing System Needs USE OF SPECIAL TOOLS AND TECHNIQUES • Special tools and techniques help the analyst make requirements determinations. • One such tool is a Data Flow Diagram, to chart inputs, processes, and output of the business’ functions in a structured graphical form. • From the Data Flow Diagram, a Data Dictionary is developed that lists all of the data items used in the system, as well as their specifications – whether they are alphanumeric or text, how much space they take up when printed. Systems Analysis and Design, Kendall and Kendall,

12. Phase 3: Analyzing System Needs ANALYZING STRUCTURED DECISIONS • Structured decisions are those for which the conditions, conditions alternatives, actions, and action rules can be determined. • There are 3 major methods for analysis of structured decisions: • structured English • Decision tables • Decision trees • Not all decisions in an organization are structured, but it is still important for the systems analyst to understand them. Systems Analysis and Design, Kendall and Kendall,

13. Phase 3: Analyzing System Needs SEMISTRUCTURED DECISIONS • These are decisions made under risk, and are often supported by decision support systems. • When analyzing semi structured decisions, the analyst examines the decisions based on: • The degree of decision making skills required • The degree of problem complexity • The number of criteria considered when the decision is made. Systems Analysis and Design, Kendall and Kendall,

14. Phase 3: Analyzing System Needs MULTIPLE CRITERIA DECISIONS • This is where many factors must be balanced. • Many techniques are available for analyzing multiple-criteria decisions, such as • Tradeoff process • Weighting methods Systems Analysis and Design, Kendall and Kendall,

15. Phase 3: Analyzing System Needs CONCLUSION • At this point of the SDLC, the systems analyst prepares a system proposal that summarizes • what has been found • provides cost/benefit analyses of alternatives • Makes recommendations on what should be done Systems Analysis and Design, Kendall and Kendall,

16. Phase 4: Designing the Recommended System • At this phase, the systems analyst uses the information collected earlier to accomplish the logical design of the information system. • The analyst designs accurate data-entry procedures so that data going into the information system are correct. • The analyst provides for effective input to the information system by using techniques of good form and screen design. Systems Analysis and Design, Kendall and Kendall,

17. Phase 4: Designing the Recommended System DESIGN USER INTERFACE • Part of thelogical design of the information system is devising the user interface. • The interface connects the user with the system and is thus extremely important. • Examples of user interface are: • Keyboard (to type in questions and answers) • On-screen menus (to elicit commands) • A variety of graphical user interfaces (GUIs), that use a mouse or touch screens. Systems Analysis and Design, Kendall and Kendall,

18. Phase 4: Designing the Recommended System DESIGN FILES AND DATABASES • This design phase also includes designing files or databases that will store much of the data needed by decision makers in the organization. • A well-organized database is the basis for all information systems. • The analyst also work with users to design output (either on-screen or printed) that meets the information needs. Systems Analysis and Design, Kendall and Kendall,

19. Phase 4: Designing the Recommended System DESIGN CONTROLS AND BACKUP PROCEDURES • The analyst must design control and backup procedures to protect the system and the data and to produce program specification packets for programmers. • Each packet should contain • input and output layouts • File specification • Processing details • Decision trees • System flowchart • Names and functions of any prewritten code routines Systems Analysis and Design, Kendall and Kendall,

20. Phase 5: Developing and Documenting Software • In this phase the analyst works with programmers to develop the original software that is needed. • Some of the structured techniques for designing and documenting software include: • Structured charts • Psuedocodes • The systems analyst uses one or more of these devices to communicate to the programmer what needs to be programmed. Systems Analysis and Design, Kendall and Kendall,

21. Phase 5: Developing and Documenting Software • The analyst also works with the user to develop effective documentation for software, including manual, online help, Web Site featuring Frequently Asked Question (FAQ), on “Read Me” files shipped with new software. • Documentation tells users how to use the software and also what to do if software problems occur. • Programmers have a key role in this phase because they design, code, and remove syntactical errors from computer programs Systems Analysis and Design, Kendall and Kendall,

22. Phase 5: Developing and Documenting Software • To ensure quality, a programmer may conduct either a design or a code walkthrough, explaining complex portions of the program to a team of other programmers (technical documentation) Systems Analysis and Design, Kendall and Kendall,

23. Phase 6: Testing and Maintaining the System • Before the information can be used, it must be tested. • It is way less costly to locate problems before the system is signed over to users. • Some of the testing is completed by programmers alone, some by systems analyst in conjunction with programmers. • Sample data and eventually actual data from the current system is used in testing the program. • Maintenance of the system and its documentation begins in this phase and is carried out routinely throughout the life of the information system. Systems Analysis and Design, Kendall and Kendall,

24. Phase 7: Implementing and evaluating the system • In this phase the analyst helps implement the information system. • This involves training users to use the system. • Some training is done by the vendor, but oversight of training is the responsibility of the systems analyst. • The analyst needs to plan for a smooth conversion from the old system to the new system. This process involves: • Converting files from the old formats to new ones or building a database. • Installing equipment • Bringing new system into production • A key criteria that must be satisfied is whether the user is actually using the system (evaluation). Systems Analysis and Design, Kendall and Kendall,

25. CONCLUSION OF SDLC • It is important to note that the system work is cyclical. • When an analyst finishes one phase of system development and proceeds to the next, the discovery of a problem may force the analyst to return to the previous phase and modify the work done there. • The analyst may need to meet with the user and reinvestigate how a specific business activity functions. Systems Analysis and Design, Kendall and Kendall,