AN OVERVIEW OF THE SDLC (STUDY OBJECTIVE 2)

The systems development life cycle (SDLC) is a systematic process to manage the acquisition, design, implementation, and use of IT systems. The oversight and management of the SDLC is normally the responsibility of the IT governance committee. The IT governance committee is usually made up of the top managers of the organization, including the chief executive officer (CEO), the chief financial officer (CFO), the chief information officer (CIO), top managers from user departments, and top management from internal audit. In addition to developing a long-term vision and objectives for IT systems, the IT governance committee oversees the SDLC.

In the early days of computers, most organizations had to develop, program, and implement accounting software in-house. It was not feasible to buy accounting software, nor was it available at a reasonable price. During that time, the SDLC was a systematic set of regular steps to accomplish the IT systems selection, design, programming, and implementation. The phases of the SDLC are depicted in Exhibit 6-1 and are briefly defined as follows:

Exhibit 6-1 An Overview of the Systems Development Life Cycle

1. 1. Systems planning is the evaluation of long-term, strategic objectives and the prioritization of the IT systems in order to assist the organization in achieving its objectives. Systems planning also involves the planning and continuing oversight of the design, implementation, and use of those IT systems.
2. 2. Systems analysis is a study of the current system to determine the strengths and weaknesses and the user needs of that system. Analysis requires the collection of data about the system and the careful scrutiny of those data to determine areas of the system that can be improved.
3. 3. Systems design is the creation of the system that meets user needs and that incorporates the improvements identified by the systems analysis phase.
4. 4. Systems implementation is the set of steps undertaken to program, test, and activate the IT system as designed in the system design phase.
5. 5. Operation and maintenance is the regular, ongoing functioning of the IT system and the processes to fix smaller problems, or “bugs,” in the IT system. During operation, management should request and receive ongoing reports about the performance of the IT system.

Notice that the SDLC is a cycle that eventually loops back to systems planning. This is true because the IT governance committee must continually evaluate how well the current IT systems match the company's strategic objectives. At some point, the IT governance committee will most likely find it necessary to go back through the phases of the SDLC to design new and improved IT systems.

As computers and IT systems have become more complex, more comprehensive, and more common, some steps in the phases in the SDLC have evolved to be slightly different. The major difference now, compared with earlier days of computers, is that the majority of companies purchase the accounting software they use rather than designing and programming the software in-house. However, even when accounting software is purchased, it may require extensive modification to make it fit the organization's needs. Therefore, even when purchasing accounting software, it is important to use a systematic, regular set of steps to evaluate, purchase, modify, and implement the software. The SDLC phases may be slightly different, but still comprise necessary steps for the proper strategic management of IT systems.

The remaining sections of this chapter describe the phases and steps of the SDLC in the modern IT environment. A process map overview of a typical SDLC appears in Exhibit 6-2. Not every organization follows each of these steps in the exact sequence shown; the SDLC phases can vary from organization to organization. The more important factor is that an organization follows a set of logical, systematic steps when modifying or adopting new systems. The exact steps and their sequence are not as critical as the need to formalize and conduct those steps completely and consistently. As a corollary, think about how companies conduct their budgeting procedures. Different companies may go about building their budgets in different ways. Some may use a bottom-up approach where lower level managers build budgets for their area and those budgets are submitted up the chain of management where they are consolidated into one overall budget. Other companies may budget from the top down. In either case, the method chosen should fit the company. The important factor is that the company has a working budgeting process, not whether it uses a particular method. Likewise, it is important that the SDLC have a logical sequence of phases, but those phases may vary slightly from company to company.

Exhibit 6-2 Process Map of the System Development Life Cycle (SDLC)

The process map shows the same phases as the SDLC overview in Exhibit 6-1, but with an expanded set of processes within the system design phase. These expanded processes are necessary because there is usually more than one software or system type that meets the needs of the organization. For example, if a company wishes to modify the payroll processes and systems in use, there are several ways to approach the modification. The company could do timekeeping in-house, but outsource the actual payroll processing to a payroll processing firm. Second, the company could buy or write a stand-alone payroll processing program. As a third alternative, the company could buy or write an integrated payroll system as part of a more comprehensive human-resource-management software system. To guide this process of designing a new payroll system, the company should have defined steps that identify the alternative system approaches, evaluate the fit of each alternative to the company's needs, select the best fit, and design or buy that system.

The process map in Exhibit 6-2 shows these various phases of the SDLC. Conceptual design is the process of matching alternative system models with the needs identified in the system analysis phase. Evaluation and selection is the process of assessing the feasibility and fit of each of these alternative conceptual approaches and selecting the one that best meets the organization's needs. The best system may be either software that can be purchased, or a system designed and developed in-house. If software is to be purchased, the company must undergo a set of steps called software selection to select the best software for its needs. When systems are to be developed in-house, the company must undertake steps to design the details of that system. Detailed design is the process of designing the outputs, inputs, user interfaces, databases, manual procedures, security and controls, and documentation of the new system.

THE PHASES OF THE SDLC

The sections that follow build upon the overview of the SDLC phases, examining each phase in detail. As mentioned previously, it is important to remember that the descriptions presented here are for a typical set of phases and steps within the SDLC and are not intended to imply that every organization must follow these exact steps.