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Unformatted text preview: 1 Understanding and Achieving Quality Attributes Ch4 and 5 Outline Â¡ Business and architectural qualities Â¡ System qualities Â¢ Availability Â¢ Performance Â¢ Security Â¢ Modifiability Â¢ Testability Â¢ Usability Business Qualities Â¡ Time to market Â¡ Cost and benefit Â¡ Projected lifetime Â¡ Target market Â¡ Rollout schedule Â¡ Integration with legacy Architectural Qualities Â¡ Conceptual integrity Â¡ Correctness and completeness Â¡ Buildability System Qualities Â¡ Availability Â¡ Performance Â¡ Security Â¡ Modifiability Â¡ Testability Â¡ Usability How to achieve Quality Attributes? Â¡ Through only Â¢ Architectural design? Â¢ Attention to Detail implementation? Example quality attributes Â¡ Usability Â¢ Architectural? Â¡ Cancel, undo, re-use data Â¢ Detail? Â¡ radio button, checkbox, font, size 2 How to achieve Quality Attributes? Â¡ Modifiability Â¢ Architectural? Â¡ Functionality division, grouping Â¢ Detail? Â¡ Coding technique Â¡ Performance Â¢ Architectural? Â¡ Amount of communication, Â¡ functionality allocation, Â¡ shared resource allocation Â¢ Detail? Â¡ Choice of algorithms Â¡ Algorithm implementation Architecture and Quality attributes Â¡ Architecture is critical to the realization of many qualities of interest in a system Â¡ Architecture, by itself, is unable to achieve qualities. Â¢ Provides foundation but still need to pay attention to details Achieving Quality Attributes Â¡ Understand quality attribute requirement Â¢ Problems: Â¡ Definition not operational, testable Â¡ Which quality a particular aspect belongs to Â£ System failure Â£ Availability? Â£ Security? Â£ Usability? Â¡ Each attribute community has its own vocabulary Â¢ Solution: Â¡ Quality attribute scenario Â£ A way of characterizing quality attribute Â¡ Design decisions used to achieve quality attribute Â¢ tactics Quality Attribute Scenario Â¡ A quality-attribute-specific requirement. Â¢ Source of stimulus Â¡ Some entity (a human, a computer system â€¦) that generated the stimulus. Â¢ Stimulus Â¡ A condition that needs to be considered when it arrives at a system. Â¢ Environment Â¡ Stimulus occurs within certain conditions. Â¢ Artifact Â¡ Some artifact is stimulated. Could be whole system or some pieces of it. Â¢ Response Â¡ The activity undertaken after the arrival of the stimulus. Â¢ Response measure Â¡ Response should be measurable so that the requirement can be tested Quality Scenarios - Table Â¡ Source Â¡ who? Â¡ Stimulus Â¡ what? Â¡ Artifact Â¡ where? Â¡ Environment Â¡ when?...
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- Spring '10
- Ripple effect, quality attribute