System Analysis and Design PDF

System Analysis and Design System Development Life Cycle  Introduction Building an information system is similar to building a house. First the owner describes the vision (that is, the type and structure) of the house to the developer. Second, the vision is transformed...

System Analysis and Design System Development Life Cycle  Introduction Building an information system is similar to building a house. First the owner describes the vision (that is, the type and structure) of the house to the developer. Second, the vision is transformed to sketches and drawings often revised by the owner until the owner agree. Third, a detail blueprint of the house is provided (e.g. layout of rooms, electrical outlet, plumbing placement and so on). Finally, the house is built following the blueprint, and often changes and decisions are made by the owner as the house is being erected.  Introduction Cont. Building an information system using software development life cycle (SDLC) follows a similar four fundamental phases: Planning, Analysis, Design and Implementation. Each of this phase consists of various steps, which relies on techniques and produce deliverables (specific document and files that explain the various elements of the system). The figure 1 below depicts that SDLC phases follows a logical path. This may be true. However, the project team moves through the steps consecutively, incrementally, iteratively, or in other patterns. Introduction Cont. Figure 1: SDLC Phases  SDLC - Planning Planning phase is an important phase that explain why an information system should be built and how the development team will go about building it. It has two steps as follows: 1. During project initiation – to identify system’s business value to the organization – how will it lower costs or increase revenues? Most of the ideas for new system comes outside IS department (mostly from operation, accounting department, etc.) in form of 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.  SDLC – Planning Cont. 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 IS approval committee ( sometimes called steering committee for approval whether the project should be undertaken.  SDLC – Planning Cont. 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.  SDLC – Planning Cont. Figure 2: Elements of the System Request Form  SDLC – Planning Cont. Figure 3: Feasibility Analysis Assessment Factors  SDLC – Planning Cont. Figure 4: Example of Costs and Benefits for Economic Feasibility  SDLC – Planning Cont. Figure 5: Steps to Conduct Economic Feasibility Analysis  SDLC – Planning Cont. Figure 6: Important Stakeholders for Organizational Feasibility  SDLC - 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. 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).  SDLC – Analysis Cont. 2. The next step is requirements gathering (e.g., through interviews, group workshops, or questionnaires). The analysis of this information with project sponsor and other stakeholders leads to development of system concept. The system concept is then the basis to develop business analysis models that describes how the business will operate if the new system were developed. The typical models represents data and process that support underlying business process.  SDLC – Analysis Cont. 3. The analyses, system concept, and models are combined into a document called the system proposal, which is presented to the project sponsor and other key decision makers (e.g., members of the approval committee) who will decide whether the project should continue to move forward. The system proposal is the initial deliverable that describes what business requirements the new system should meet.  SDLC - Design The design phase decides how the system will operate in terms of the hardware, software, and network infrastructure that will be in place; the user interface, forms, and reports that will be used; and the specific programs, databases, and files that will be needed. The design phase has four steps: 1. The design strategy must be determined. This clarifies whether the system will be developed by the company’s own programmers, whether its development will be outsourced to another firm (usually a consulting firm), or whether the company will buy an existing software package.  SDLC – Design Cont. 2. This leads to the development of the basic architecture design for the system that describes the hardware, software, and network infrastructure that will be used. In most cases, the system will add to or change the infrastructure that already exists in the organization. The interface design specifies how the users will move through the system (e.g., by navigation methods such as menus and on-screen buttons) and the forms and reports that the system will use. 3. The database and file specifications are developed. These define exactly what data will be stored and where they will be stored.  SDLC – Design Cont. 4. The analyst team develops the program design, which defines the programs that need to be written and exactly what each program will do. This collection of deliverables (architecture design, interface design, database and file specifications, and program design) is the system specification that is used by the programming team for implementation.  SDLC - Implementation The final phase in the SDLC is the implementation phase, during which the system is actually built (or purchased, and installed). This is the phase that usually gets the most attention, because for most systems it is the longest and most expensive single part of the development process. This phase has three steps: 1. System construction - The system is built and tested to ensure that it performs as designed. Since the cost of fixing bugs can be immense, testing is one of the most critical steps in implementation. Most organizations spend more time and attention on testing than on writing the programs in the first place.  SDLC – Implementation Cont. 2. The system is installed. Installation is the process by which the old system is turned off and the new one is turned on. There are several approaches that may be used to convert from the old to the new system. One of the most important aspects of conversion is the training plan, used to teach users how to use the new system and help manage the changes caused by the new system. 3. The analyst team establishes a support plan for the system. This plan usually includes a formal or informal post-implementation review, as well as a systematic way for identifying major and minor changes needed for the system.