system quality attributes for software architecture
DESCRIPTION
Software Quality Attributes are the benchmarks that describe system’s intended behavior. These slides go through an overview of what some of these attributes are and how to evaluate them.TRANSCRIPT
FUNCTIONAL / NON FUNCTIONAL REQUIREMENTS AND SOFTWARE ARCHITECTURE MEASURE OF TEAM
EMPHASIS ON TRADEOFF DECISIONS
ADNAN MASOODSR. SOFTWARE ARCHITECT & DOCTORAL
CANDIDATEBLOG.ADNANMASOOD.COM
System Quality Attributes
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Definition
“Software Quality Attributes are the benchmarks that describe system’s intended behavior within the environment for which it was built. The quality attributes provide the means for measuring the fitness and suitability of a product. Software architecture has a profound affect on most qualities in one way or another, and software quality attributes affect architecture.”
Functional Requirements
In general, functional requirements define what a system is supposed to do usually in the form of "system shall do
<requirement>“Functional requirements define specific
behavior or functions.The plan for implementing functional
requirements is detailed in the system design.
Non-Functional Requirements
Non-functional requirements define how a system is supposed to be.
Non-functional requirements specify criteria that can be used to judge the operation of a system, rather than specific behaviors.
The plan for implementing non-functional requirements is detailed in the system architecture.
System Quality Attributes
Non-functional requirements specify system quality attributes.
Other terms for non-functional requirements are: Constraints Quality attributes Quality goals Quality-of-service (QoS) requirements Non-behavioral requirements
Informally, these are known as the “-ilities"
System Quality Attributes Business Perspective
Suitability: Functionality is suitable to all end users Compliance: Functionality is compliant with applicable regulatory
guideline Certifiability: System is able to be certified to some standard by an
independent third party
• Conformance: Conformance to industry and operational standards
Accessibility: The user interface can be accessed and utilized by differently abled users
Adaptability: Ability to change the system components to meet new business needs
Extensibility & Modifiability: Ability to easily add new features and customizations
Replaceability: Ability to replace system in the future Reporting: The system supports generating various reports
System Quality AttributesSecurity Perspective
Security: System is secure: confidentiality, integrity, availability, accountability and assurance
Privacy: System does not reveal (or allow revealing) of information to improper parties
Non-exploitability: The system, its components, and its configurations are hardened against known and unknown security vulnerabilities
Accountability: The system records all user interactions and data changes
Auditability: The system makes accountability information available to managers and operators
System Quality AttributesPerformance Perspective
Efficiency: System does not waste valuable resourcesPerformance: Perceived response is immediateScalability: Able to handle increased usage on the
appropriate amount of resources, able to add resources quickly and easily to handle increases in demand
Responsiveness: The system responds to interactions with minimal delay and/or latency
Capacity: The system can handle sudden peaks and surges in demand
Throughput: The system can handle a specified number of interactions or transactions within a specified duration without undesirable degradation in terms of other qualities
System Quality AttributesConfiguration Perspective
Configurability: Ease of making configuration changesIntegrity: The system, its configuration, and its
data cannot be changed by unauthorized parties(including accidental or deliberate misconfiguration)
• Deployability: Ease of installation, reinstallation, and updating
Portability: System supports changes in choice of underlying technologies and architectures (such as database platform, operating system platform, etc.)
Interoperability & Compatibility: Functionality interoperates with other systems easily
System Quality AttributesOperations Perspective
Availability & Fault Tolerance: System continues operating properly in the event of failure by one or more of its components
Isolation: System survives and gracefully handles situations in which dependent “downstream” systems become unavailable
Continuity: System recovers from failures in surrounding environment Disaster Recoverability: The system, its data, and its configuration can be completely
and quickly recovered from backups and configuration management repositories, even in the event of a catastrophic loss of a data center
Operability: System can readily be kept in a functioning and operating condition by manual or automated means
• Maintainability: System upgrades can quickly and safely be performed with a minimum of downtime
• Monitorability: Ability for operators to easily see how the system is operating
• Alerting: The system notifies operators of faults and exceptional conditions
• Maturity: System components are proven stable by others• Stability and Reliability: The system exhibits infrequent failures
System Quality AttributesData Perspective
Durability: The system does not lose critical operational data, whether “in-flight” or “at-rest”
Reversibility: Undesirable system and data changes can be reversed quickly and easily with minimal disruption to the business
Cacheability: The data is structured with appropriate separation of volatile (changing) and non-volatile data to support caching
Archivability: Older data can be relocated to separate data stores Partitionability: The system supports splitting like-kind data across
multiple databases (for scalability, risk mitigation, etc.) Idempotency: Interactions performed twice result in same change as if
performed once Concurrency: The system supports a high degree of simultaneous
interactions with the database without degrading in performance or sacrificing data integrity (ex: optimistic locking, snapshot isolation)
Backup : The database and message queues support being backed up without the system being taken offline
System Quality AttributesDiagnostics Perspective
Supportability: System operators can quickly and easily identify faults and perform root cause analysis within an environment of controlled access to information and restricted privileges
Instrumentability: System is capable of recording various operational metrics that can be analyzed and reported on
Traceability: System can be configured to record its own interactions with itself in order to aid support personnel in diagnosing problems
• Logging: The system logs external and interactions with configurable degrees of detail
System Quality AttributesEnhancement Perspective
Analyzability: Ability to figure out how the system functions
Documentability: Ability to communicate about the system in writing
Understandability: Able to use system with little training
Learnability: Supports learning of system functionality with little external interfacing
• Testability: Ability to create repeatable and specific tests of the system and potential for some to be automated
Software Quality Attributes Ratings Tool
http://www.gettingagile.com/wp-content/uploads/2009/05/softwarequalityattributes-ratingtool.xls OR
http://bit.ly/1aIPeU1
References
Getting Agilehttp://www.gettingagile.com/2009/05/17/survey-for-software-quality-attributes-where-should-we-focus/
MSDN – Quality Attributeshttp://msdn.microsoft.com/en-us/library/ee658094.aspx
Implementing System Quality Attributeshttp://msdn.microsoft.com/en-us/library/bb402962.aspx
Operational Aspects of a System – ACM Queuehttp://queue.acm.org/blogposting.cfm?id=56822
about software engineeringabout software industryarchitect softwarearchitecture softwarearchitecture software programsdesign and softwaredesign and user experiencedesign for user experiencedesign user experienceenterprise architectenterprise architectsenterprise it architectit quality assurancemanagement quality systemprogram qualityquality assurancequality assurance for softwarequality assurance in softwarequality assurance softwarequality in softwarequality programquality softwarequality systemquality systems managementrequirements softwaresoftware architectsoftware architect softwaresoftware architectssoftware architecturalsoftware architecture softwaresoftware businesssoftware development cyclesoftware engineeringsoftware engineering bysoftware for quality assurancesoftware for software engineeringsoftware metricssoftware qualitysoftware quality assurancesoftware quality assurance softwaresystem architectsystems qualitysystems quality management