Quality Attributes Scenarios

A quality attribute scenario is a quality-attribute-specific requirement. It consists of six parts.

  1. Source of stimulus: This is some entity (a human, a computer system, or any other actuator) that generated the stimulus.
  2. Stimulus: The stimulus is a condition that needs to be considered when it arrives at a system.
  3. Environment: The stimulus occurs within certain conditions. The system may be in an overload condition or may be running when the stimulus occurs, or some other condition may be true.
  4. Artifact: Some artifact is stimulated. This may be the whole system or some pieces of it.
  5. Response: The response is the activity undertaken after the arrival of the stimulus.
  6. Response measure: When the response occurs, it should be measurable in some fashion so that the requirement can be tested.

The figure below shows the parts of a quality attribute scenario.

Figure 4.1 Quality attribute parts.

Figure 4.1 Quality attribute parts.

The purpose of this is to be able to figure out the ways you can estimate and improve the software. There are many software quality attributes, but for this course, we will only focus on six of them.

Performance

Performance is the ability of a system to respond in a timely and efficient manner to user requests. From these considerations we can see the portions of the performance general scenario.

Users initiate 1,000 transactions per minute stochastically under normal operations, and these transactions are processed with an average latency of two seconds.

Figure 4.2 Sample performance scenario.

Figure 4.2 Sample performance scenario.