Quality Attributes Scenarios

Quality Attributes

• Measurable or testable properties of a system
  Used to indicate how well the system satisfies the needs of its stakeholders
  Emergent properties : not a measure of software in isolation

 

Quality Attributes : Taxonomies

• ilities
  understandability, usability, modifiability, interoperability, reliability, portability, maintainability, scalability, sonfigurability, customizability, adaptability, cariability, volatility, traceability
• ities
  security, simplicity, claity, ubiquity, integrity, modularity
• ness
  user-friendliness, robustness, timeliness, responsiveness, correctness, completeness, conciseness, cohesiveness
  
• others
  performance, efficiency, accuracy, precision, cost, development time, low coupling

 

Qaulity Attribute Scenarios

• QAS is an effective way of identifying and specifying quality-attribute-specific requirements.
• Specific to the particular system under considerations
• Instantiated from the attirubte characterizations of general scenarios
• A QAS Example for Availability : An unanticipated external message is recevied by a process during normal operation. The process informs the operator of the receipt of the message and continues to operated with no downtime.

Tactics

• Techniques that architects have been using for years to manage quality attribute response goals.
  Design decisions that influence the control of a quality attribute response

 

QAS example

• Raw Scenario : In the event of hardware failure, search service is expected to return results during normal working hours for US services representatives.

• Refined Scenario : in the event of hardware failure, search service is expected to return results within 5 sec, in 12 average QPS.