System Development Life Cycle (SDLC) - Purpose and Stages

Syllabus Detail

  • Purpose and stages of the SDLC 11 GEN, 12 GEN, 11 ATAR, 12 ATAR

What is the SDLC?

  • The System Development Life Cycle (SDLC) is a process commonly used for planning, creating, testing and deploying an information system
  • It can apply to software, hardware, or a combination of both
  • The SDLC is defined by a number of clearly grouped activities, known as phases used to develop a finished project or product

Why do we use the SDLC?

  • The SDLC gives us a structured, easy to follow approach when developing an information system
  • Phases allow us to break down each step in the development and allows for less error or discrepancies due to planning

The SDLC Phases

  • 1. Preliminary analysis.= First we define the problem of the system. Once complete we can allocate resources and prioritize tasks.
    • We often create a feasibility report to test if the project can be done.
    • It includes technical feasibility, if it is operational, if it is economically sustainable and if it fits within the schedule
    • This can be remembered with the acronym TOES
  • 2. Analysis = we define the project goals based off the client or end-user's needs.
    • We work out a model of the current system. We create business rules based on user needs, ER diagram can start here, normalisation to search out redundancy issues.
    • We find out the requirements of the new system.

  • 3. Design = we design both the physical and logical parts of the system.
    • The logical design = an abstract design usually by modelling. Entity Relationship Diagrams are a part of this. 
    • The physical design = the technology-specific details from which all programming and system construction can be accomplished.

    • Students often jump to the physical design of most tasks in schools.
    • If they took time to make a logical design, the final product would be better and could be made to physical designs by students with variety.
    • For example a logical design for a system to improve ordering from the canteen will include an ER diagram of the improved lunch order system. The actual physical design would change according to who was making it, based on the logical (planning).
    • Student A may create a physical design that needed iPads to input name for lunch order.  At locations in the canteen and Student B may create a physical design for a system that required a barcode scanning of an ID card. Yet both of these students are looking at a logical ERD that states, collect student name.
  • 4. Development = we gather our resources and build and test the system.
    • The resources we obtain are the hardware and software that is needed.
    • The system is created and tested.

  • 5. Implementation = we implement the new system into its environment.
    • This can be done in many ways, each with their own advantages and disadvantages.
    • The ways this can be done are as follows:
      • Direct cut = the old system is replaced fully by the new system.
      • Pilot  = a select group are given access to trial the new system before implementing globally.
      • Parallel = both systems are run simultaneously until the new one is considered stable and usable.
      • Phased = parts of the new system are implemented as seen fit until the new system is fully installed.

    6. Evaluation & Maintenance

    • We evaluate the performance of the system to make sure the new system is working and fits the requirements from the pre-analysis and analysis stages.
    • We conduct fault finding and make corrections. 

 

Step 5 - Further Research

  1. Differences between logical and physical ERDs  here.

 

 

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Updated Feb '17