THE SYSTEMS DEVELOPMENT LIFE CYCLE
In many ways, building an information system is similar to building a house. First, the owner describes the vision for the house to the developer. Second, this idea is transformed into sketches and drawings that are shown to the owner and refined (often, through several drawings, each improving on the other) until the owner agrees that the pictures depict what he or she wants. Third, a set of detailed blueprints is developed that presents much more specific information about the house (e.g., the layout of rooms, placement of plumbing fixtures and electrical outlets, and so on). Finally, the house is built following the blueprints—and often with some changes and decisions made by the owner as the house is erected. Building an information system using the SDLC follows a similar set of four fundamental phases: planning, analysis, design, and implementation (Figure 1-2). Each phase is itself composed of a series of steps, which rely on techniques that produce deliverables (specific documents and files that explain various elements of the system). Figure 1-3 provides more detail on the steps, techniques, and deliverables that are included in each phase of the SDLC and outlines how these topics are covered in this textbook. Figures 1-2 and 1-3 suggest that the SDLC phases proceed in a logical path from start to finish. In some projects, this is true. In many projects, however, the project team moves through the steps consecutively, incrementally, iteratively, or in other patterns. Different projects may emphasize different parts of the SDLC or approach the SDLC phases in different ways, but all projects have elements of these four phases. For now, there are two important points to understand about the SDLC. First, you should get a general sense of the phases and steps that IS projects move through and some of the techniques that produce certain deliverables. In this section, we provide an overview of the phases, steps, and some of the techniques that are used to accomplish the steps. Second, it is important to understand that the SDLC is a process of gradual refinement. The deliverables produced in the analysis phase provide a general idea what the new system will do. These deliverables are used as input to the design phase, which then refines them to produce a set of deliverables that describes in much more detailed terms exactly how the system should be built. These deliverables in turn are used in the implementation phase to guide the creation of the actual system. Each phase refines and elaborates on the work done previously.
Planning
The planning phase is the fundamental process of understanding why an information system should be built and determining how the project team will go about building it. It has two steps:
1. During project initiation, the system’s business value to the organization is identified—how will it lower costs or increase revenues? Most ideas for new systems come from outside the IS area (from the marketing department, accounting department, etc.) in the form of a system request. A system request presents a brief summary of a business need, and it explains how a system that supports the need will create business value. The IS department works together with the person or department generating the request (called the project sponsor) to conduct a feasibility analysis. The feasibility analysis examines key aspects of the proposed project:
■ The technical feasibility (Can we build it?)
■ The economic feasibility (Will it provide business value?)
■ The organizational feasibility (If we build it, will it be used?) The system request and feasibility analysis are presented to an information systems approval committee (sometimes called a steering committee), which decides whether the project should be undertaken.
2. Once the project is approved, it enters project management. During project management, the project manager creates a work plan, staffs the project, and puts techniques in place to help the project team control and direct the project through the entire SDLC. The deliverable for project management is a project plan that describes how the project team will go about developing the system.
Analysis
The analysis phase answers the questions of who will use the system, what the system will do, and where and when it will be used. (See Figure 1-3.) During this phase, the project team investigates any current system(s), identifies improvement opportunities, and develops a concept for the new system. This phase has three steps:
1. An analysis strategy is developed to guide the project team’s efforts. Such a strategy usually includes a study of the current system (called the as-is system) and its problems, and envisioning ways to design a new system (called the to-be system). 2. The next step is requirements gathering (e.g., through interviews, group workshops, or questionnaires). The analysis of this information—in conjunction with input from the project s