THE TRADITIONAL SYSTEM DEVELOPMENT LIFE CYCLE

6.3 THE TRADITIONAL SYSTEM DEVELOPMENT LIFE CYCLE

Development is a very deliberate and orderly approach to making a system a reality. A methodology is needed to provide structure to system development. There are many "traditional" system development life cycles (SDLCs) for information systems, including DSS. Every computer-aided software engineering (CASE) tool has adopted a variation. Further complicating matters, each organization that develops a system can create in-house variations to suit its specific needs. Each methodology emphasizes different steps in different ways. But all SDLCs that make intuitive and practical sense must follow certain guidelines and processes.

Ideally, a need of some kind starts the process, and a completed system is its result.

A traditional SDLC consists of four fundamental phases-planning, analysis, design, and implementation (PADI)-which lead to a deployed system (Figure 6.1). The system is a cycle because it is possible to return to any phase from any other, though an ideal progression is to follow each phase in order. All projects must go through these phases. Each phase consists of a series of steps, which rely on techniques that produce deliverables. We have adopted the SDLC described by Dennis and Wixom (2003). In Table 6.1, we show the fundamental phases, the steps, and the deliverables for each step. The SDLC presentation seems to be linear, but at any time the project can be halted or can return to an earlier step in any phase. This applies to Web system development as well, though there are some specific issues which we discuss later. We now discuss the phases and steps (see Table 6.1). In Table 6.2, we show the system development phases and Web impacts.

Ideally, the project "flows" down and to the right. The upward arrows indicate that changes while developing a system can return the process to an earlier stage.

CHAPTER 6 DECISION SUPPORT SYSTEM DEVELOPMENT

Ideally, the project "flows" down and to the right. The upward arrows indicate that changes while developing a system can return the process to an earlier stage. This is also known as waterfall development.

1. Planning. The planning phase starts with a business need not being met. This includes possible opportunities identified through environmental scanning. Is there a problem that needs to be solved? Project initiation involves a system request that is decided on. If it appears worthwhile, a feasibility study (analysis) is conducted. The feasibility study considers whether the idea is viable. Questions concerning technical feasibility, cost feasibility, and organizational feasibility are answered here. If the project is approved, a project manager is assigned, and he or she creates a work plan, staffs the project, and adopts methods for managing it.

2. Analysis. The analysis phase is like a journalist's interview. It asks and answers such important questions as who the users will be, what the system will accomplish, and where and when it will run. This phase starts with the development of an analysis strategy or a plan to guide the project. If there is an existing system, it is analyzed, along with ways of moving to the new system. This leads to further information gathering, leading up to the development of a process model and a data model.

3. Design. The design phase indicates how the system will work, considering all the details of the hardware, software, network infrastructure, user interface, and so on. In this phase, the user interface, forms, displays, reports and programs, databases, and files are specified. In the design strategy, the amount of the system to be purchased or contracted (vs. built in-house) is decided on. This leads to the architecture design, which leads to the database and file design, which in turn leads to the program design. Collectively, these are the system specifications.

4. Implementation. The implementation phase brings it all together. This is where the