Chapter 3: SDLC and its Life cycle Phases.

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What is SDLC?

The systems development life cycle (SDLC), also referred to as the application development life-cycle, is a term used in systems engineering, information systems and software engineering to describe a process for planning, creating, testing, and deploying an information system.

Career Paths for System Developers

Systems Development Life Cycle

  • Building an information system using the SDLC follows a similar set of four fundamental phases:
  • Planning,
  • Analysis,
  • Design,
  • Implementation

The Systems Development Life Cycle

  • 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).

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. Project initiation
  • 2. Project management

Project initiation

  • During project initiation , the system’s business value to the organization is identified—how will it lower costs or increase revenues?
  • The IS department works 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.

Project management

  • 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
  • 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:
  • Analysis strategy
  • Requirements gathering
  • System proposal

Analysis strategy

  • 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 ).

Requirements gathering

  • The next step is  requirements gathering  (e.g., through interviews, group work-shops, or questionnaires).
  • The analysis of this information leads to the development of a concept for a new system.
  • The system concept is then used as a basis to develop a set of business  analysis models  that describes how the business will operate if the new system were developed.

System proposal

  • 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.

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:
  • Design strategy
  • Architecture design
  • Database and file specifications
  • Program design

Design strategy

  • 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.

Architecture design

  • 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.
  • 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.

Database and file specifications

  • These define exactly what data will be stored and where they will be stored.

Program design

  • The analyst team develops the  program design, which defines the programs that need to be written and exactly what each program will do.

To sum up…

  • 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.
  • At the end of the design phase, the feasibility analysis and project plan are reexamined and revised, and another decision is made by the project sponsor and approval committee about whether to terminate the project or continue.
 
Implementation
•       The final phase in the SDLC is the implementation phase , during which the system is actually built (or purchased, in the case of a packaged software design and installed).
•       It is the longest and most expensive single part of the development process. This phase has three steps:
•       System construction
•       Installation
•       Supportive plan
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.
Installation
•       Installation  is the process by which the old system is turned off and the new one is turned on.
Supportive plan
•       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.

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