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Unformatted text preview: 1 Understanding and Achieving Quality Attributes Ch4 and 5 Outline Business and architectural qualities System qualities Availability Performance Security Modifiability Testability Usability Business Qualities Time to market Cost and benefit Projected lifetime Target market Rollout schedule Integration with legacy Architectural Qualities Conceptual integrity Correctness and completeness Buildability System Qualities Availability Performance Security Modifiability Testability Usability How to achieve Quality Attributes? Through only Architectural design? Attention to Detail implementation? Example quality attributes Usability Architectural? Cancel, undo, re-use data Detail? radio button, checkbox, font, size 2 How to achieve Quality Attributes? Modifiability Architectural? Functionality division, grouping Detail? Coding technique Performance Architectural? Amount of communication, functionality allocation, shared resource allocation Detail? Choice of algorithms Algorithm implementation Architecture and Quality attributes Architecture is critical to the realization of many qualities of interest in a system Architecture, by itself, is unable to achieve qualities. Provides foundation but still need to pay attention to details Achieving Quality Attributes Understand quality attribute requirement Problems: Definition not operational, testable Which quality a particular aspect belongs to System failure Availability? Security? Usability? Each attribute community has its own vocabulary Solution: Quality attribute scenario A way of characterizing quality attribute Design decisions used to achieve quality attribute tactics Quality Attribute Scenario A quality-attribute-specific requirement. Source of stimulus Some entity (a human, a computer system ) that generated the stimulus. Stimulus A condition that needs to be considered when it arrives at a system. Environment Stimulus occurs within certain conditions. Artifact Some artifact is stimulated. Could be whole system or some pieces of it. Response The activity undertaken after the arrival of the stimulus. Response measure Response should be measurable so that the requirement can be tested Quality Scenarios - Table Source who? Stimulus what? Artifact where? Environment when?...
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This note was uploaded on 01/17/2012 for the course GCIS 518 taught by Professor Tang during the Spring '10 term at Gannon.
- Spring '10