Technical Writing Systems Development Life Cycle

The Systems Development Life Cycle (SDLC) is a logical process that helps to design good new products and software efficiently. The SDLC system emphasises planning.

The SDLC system was developed because:

Initialisation Phase

A Product user is someone who uses a product or service.

The Initialisation Phase starts when a Potential Product User with money (a Sponsor) identifies a need or wish for something new a (Goal).

This Goal may be a totally new product or a change to an existing product to make it easier to use.


Sponsors wishes are called Goals.

Sponsors want to:

Feasibility study

Many companies do a Feasibility study before the project continues to discover whether the project is possible.

Requirements and Feasibility

The Goals of the Sponsor are translated into Requirements.

A System Analyst will ask the Sponsor questions to define what the true goals are.

The System Analyst will then discuss the goals with

The team of Experts may decide that the project is not possible.

The System Analyst will then discuss this with the Sponsor to discover if the goals can be reduced or modified.


When the initial Requirements have been discovered, then the team of Experts translates the Requirements into Functions that meet the Sponsor's Goals.


Specification details all the Functions that must be in the product


Analysts must translate the Goals of the Sponsor into Functions that can be tested.

The SDLC is a process that allows:

to analyse and prioritize the Functions needed to fulfil the Goals of the Product user.

This initial description of Product User Requirements is vital to make the project succeed.


Functions are system actions caused by Product Users.

Functions must serve the Goals of the Sponsor described in the Requirements.

The Functions of the system lead to the more detailed Specification of the logical and physical system Structure.

'Functions describe WHAT must happen, then designers and developers specify HOW the function happens in the Structure.


Structures both support and limit the system.

Structures respond to the environment of the Users, as well as the capabilities of the developers.

Structures provide interfaces, data, workflow, integration, safety, and security. Together, they are tested and delivered to the Users as a Product.

The Users interact with the Product. If the User's Goals are met in the Functions of the Product, the process continues allowing the User to discover new Goals and developers to add new Functions and Structures in the system.


Product users achieve these Goals by using Products. The Products must satisfy all the requirements

When these Products need an improvement then we return to the Goals of the product user.

Example 1

  1. The Product users have cars
  2. The Product users work for the same company. All the cars are basically the same model.
  3. The cars are economical (The cars are modern fuel efficient Skodas)
  4. The Product Users wish to drive to Switzerland for a company sponsored holiday.
  5. The Product Users wish to add a container above the car to transport skis without loss of performance.

The task is to design and produce a container which will not affect performance beyond certain limits

The Analyst must ask the Product User the following questions to define the task:

  1. What constitutes a loss of performance. The engine of the car will perform within the manufacturers specifications. The real performance of the car will not become worse. But:
    • The additional container will introduce drag and drag will decrease the speed of the car and increase the quantity of fuel that the engine uses
    • The additional weight will decrease the speed of the car and increase the quantity of fuel that the engine uses
  2. How many skis must the container carry?. Suggest no more pairs of skis than the number of passengers.
  3. What is the total weight of the skis? ( this affects the performance per litre of fuel)
  4. What dimensions are the skis ( this affects the dimensions of the container)
  5. How can the container be attached to the roof of the car?
  6. When must the container be ready?


  1. Why did projects fail before the SDLC? Products were designed without market research.
  2. What job does an analyst perform? The analyst translates the Sponsor's goals into testable Functions.
  3. With whom should an analyst discuss the initial requirements? The Sponsor.
  4. Why do companies run feasibility studies? To determine if the proposed product is capable of being developed into a strong revenue-producing product.