Computer Science

System design and analysis

What is a system?

  • A system is a set of interacting parts that operate together to achieve some objective or purpose.

Three stages of a system

Input -> Process -> Output

  • Something feeds into the system (the input).
  • The system does something with the input (the process).
  • The process gives a result (the output).

Computer Systems

  • A system of interconnected computers that share a central storage system and various peripheral devices such as printers, scanners, or routers.
  • Each computer connected to the system can operate independently but has the ability to communicate with other external devices and computers.

System Development Life Cycle (SDLC)

  • A process for planning, creating, testing, and deploying an information system.
  • The SDLC concept applies to a range of hardware and software configurations as a system can be composed of hardware only, software only, or a combination of both.

Feasibility Check (TELOS)

Analysis to see if an idea/project is possible and not breaking any rule.

  • TELOS acronym checks for failure, not opportunity:
    • Technology: Does the required technology exist?
    • Economic: Is the price required to pay and maintain the system accessible?
    • Legal: Is your operation legal?
    • Operational: Is there enough workforce or structure for the system to run?
    • Schedule: Is there enough time to create and maintain the system?

Stakeholders

  • A stakeholder is a person, group, or organization that has an interest or concern in an organization.
  • Examples: Creditors, Directors, Clients, Developers, Government, Owners, Suppliers, etc.
  • Key stakeholders: Client, Developers, and End-User.

Exam Tip

When identifying stakeholders for a new system, be sure to ask:

  • Who will be affected by the new system?
  • Who will the new system affect?
  • Who will the end-users be?
  • What are their needs?

Internal vs External Stakeholders

  • Internal: Employees, owners, representatives of a company (e.g. managers).
  • External: Suppliers, customers, society, governments, creditors (e.g. loan), and shareholders.

Utilitarianism

  • When designing a new system, we usually try to design it for the greatest good for the greatest number of people; this is called utilitarianism.

Methods of Obtaining Requirements

  • Direct observation: Walking around the company and observing how things are done.
  • Interviews: Interviewing key people within the system to find out how it works.
  • Surveys: Handing out questionnaires for people to fill out (either online or physical).
  • Collecting documents: Looking in the documents currently being used in the system to try to find out how the present system works.