© peer törngren 1 itarc may 2015 quality attributes of software architecture quality attributes of...
TRANSCRIPT
© Peer Törngren
1
ITARC
May 2015
Quality attributes of Software Architecture
Quality Attributes of Software Architecture
What is software quality? Does architecture affect system quality?
What is the value of software quality?
Peer Törngren
30 years
in
30 min
utes
© Peer Törngren
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Agenda
• Intro (about quality, about me)• Quality Attributes• Measurements • Summary
May 2015
Quality attributes of Software Architecture
o Performanceo Scalabilityo Security and Integrityo Availability (uptime/downtime)o UX: Usability, Accessibility and Aestheticso Globalization (i18N, L10N, G11N)o Robustnesso Technical Flexibilityo Adaptability (Integration and Customization)o Administrationo Vitality (life expectancy)
CAUTION: (VERY) BRIEF OVERVIEW!
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About Quality
May 2015
Quality attributes of Software Architecture
• “Best Quality” - for what and whom?– There is often contradiction. What matters most?– There is always a price. What is your budget?
• Quality is subjective and context sensitive– What is quality – to YOU?– What is it worth – to YOU?
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About Software (Architecture) Quality
• Software architecture drives quality of software systems– architecture manifested in concrete system– architecture quality visible in concrete systems
• Software quality requirements drive architecture• Formal
– ISO/IEC 25010:2011 Systems and software Quality Requirements and Evaluation
– ISO/IEC 9126 Software engineering – Product quality
May 2015
Quality attributes of Software Architecture
There is no single ”perfect” system or architecture!
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QUALITY ATTRIBUTES
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Quality attributes of Software Architecture
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Performance
• Speed (single user)• Load (multiple users – predictable, linear?)• Capacity (data volume – predictable, linear?)• Bandwidth and network dependency (asynchronous?)• Latency (chatty protocol?)• Footprint (resources)
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Quality attributes of Software Architecture
What if the system gets faster with more users and more
data?
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Performance
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Quality attributes of Software Architecture
Like a rowing team, or a rapid stream.
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Scalability
• Ability to adapt– Scale up (for performance)– Scale down (for economy)
• Ways to adapt– Vertical (bigger engine)– Horizontal (more engines)
• Time and effort to adapt– Manual (reconfigure and restart)– Dynamic (reconfigure ”in flight”)– Elastic (monitor and adapt automatically)
May 2015
Quality attributes of Software Architecture
What if the system would learn proactively scale to anticipated
load?
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Scalability
May 2015
Quality attributes of Software Architecture
Like a mall scaling up for Christmas,
or a bar scaling down on Monday.
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Security and Integrity
• Authentication – who are you?• Authorization – what can you do?• Audit Trail – what was done by who? And not?• Administration/Integration
– single sign-on– report/verify user permissions– user permissions synchronized across systems
• Integrity– sensitive data (personal)– “big data” analytics
• Threats – Attacks (internal/external)– Accidents
May 2015
Quality attributes of Software Architecture
What if the system could
detect and fight infections and self heal
from injuries?
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Security and Integrity
May 2015
Quality attributes of Software Architecture
Like the human body, or any living
organism.
(antibodies)
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Availability
• Reliability (uptime, MTBF)– System failure statistics?– Scheduled downtime (maintenance)?– Auto failover (”hot swap”, clusters)?
• Serviceability (downtime)– ”Hot” update?– Average downtime for service?– Average time to find and fix defects?
May 2015
Quality attributes of Software Architecture
What if the system never
goes down or is rebooted
for any reason? Ever?
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Availability
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Quality attributes of Software Architecture
Like the Internet.
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UX: Usability, Accessibility and Aesthetics
• Usable?– Novice vs veteran– Frequent power user vs random guest
• Accessible?– Mouse/keyboard?– High Contrast?– Screen reader?
• Good Looks?– Demo friendly (first impression, wow factor)– User friendly (lasting impression)– Modern (”in fashion”)
May 2015
Quality attributes of Software Architecture
What if the system was individually
“skinnable” to the taste of each user?
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UX: Usability, Accessibility and Aesthetics
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Quality attributes of Software Architecture
Like a cell phone.
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Globalization (i18N, L10N, G11N)
• Not just character sets and language …– UTF-8/UTF-16– Variants of English, German, Swedish …– Different regional settings (time/date formats)– Time zones (and daylight savings time)– Calendars– Holidays– BiDi (bidirectional), LTR/RTL– GUI (widget) mirroring– Icons (visual language)– Colors
• What do you need? What do you value? What can it cost?
May 2015
Quality attributes of Software Architecture
What if the system could be localized by anyone
at any time, when the need
arises?
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Globalization (i18N, L10N, G11N)
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Quality attributes of Software Architecture
Like books and movies.
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Robustness
• Productivity– Entry (learning threshold)– Evolution (adding/changing features)– Troubleshooting (finding and fixing defects)
• Problems– Complex dependencies– Complex combinatorial state– High Coupling/Low Cohesion– Unclean code
• Support– Documentation– Tooling– Online knowledge (community forums)
May 2015
Quality attributes of Software Architecture
What if the system would avoid bad code and let it
atrophy?
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Robustness (Complexity, Productivity)
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Quality attributes of Software Architecture
Like unused muscles.
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(Technical) Flexibility
• Multiple platforms (.Net/Java, Windows/Linux, Android/iOS, …)
• Multiple data sources (Oracle, SQL Server, DB2 …)• Standards conformance (http, JSON, JPA, WSDL …)
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Quality attributes of Software Architecture
What if the system would run in any technical
environment?
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Flexibility
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Quality attributes of Software Architecture
Like immigrants in a foreign country.
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Adaptability
• Integration (other systems)– Adapters (ERP systems)– Configuration
• Customization (business rules and behavior)– Extension Points (plugin architecture)– Dynamic types (dynamic object model)
May 2015
Quality attributes of Software Architecture
What if systems would negotiate, invent and adapt the best style of communication, interaction and
behavior?
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Adaptability
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Quality attributes of Software Architecture
Like kids in the playground.
Or social people in general.
Like Darwin taught us.
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Administration
• Installation (automated)• Updates (no downtime)• Monitor and Control (standards, eg JMX, System Center)• Error handling (logs)• DevOps (cloud?)
May 2015
Quality attributes of Software Architecture
What if the system didn’t need a
system administrator?
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Administration
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Quality attributes of Software Architecture
Like a self service restaurant or
shop.
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Vitality (life expectancy)
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Quality attributes of Software Architecture
• Financial State (vendor, sponsors)• Active Community (open source or commercial)• Release Frequency• Roadmap• Number of users
What if the system was immortal?
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Vitality (life expectancy)
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Quality attributes of Software Architecture
Like Gandalf? Like a lobster? Like Madonna?
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MEASURES
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Quality attributes of Software Architecture
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How to Measure Quality
• Benchmark (performance)• Metrics and Statistics (reliability, serviceability)• Certification (security, globalization, accessibility,
administration)• Prototype (performance, productivity)• Online activity (vitality, robustness)• Inspection and Evaluation (adaptability, flexibility)• Survey (usability, aesthetics)• Track Record and Reputation (all of the above?)
May 2015
Quality attributes of Software Architecture
Beauty is in the Eye of the Beholder …Context matters; best fit wins!
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SUMMARY
What is software quality? Does architecture affect system quality?What is the value of software quality?
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Quality attributes of Software Architecture
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What is Software Quality?
• subjective, relative and context sensitive• contradictive or paradoxical (sometimes)• predictable and measurable (mostly)• assessable (always) • not free (ever)
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Quality attributes of Software Architecture
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Does Architecture Affect System Quality?
• Architecture indicates system quality• Systems verify architecture quality• Quality must be put in context• Test – look at these two vehicles:
– Which seems faster? – Which seems to carry more load?– Does the architecture matter?– Does intended usage matter?
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Quality attributes of Software Architecture
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What is the Value of Software Quality?
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Quality attributes of Software Architecture
• Which attributes are valuable– to you?
• How valuable are they– to you?
• How do you measure value – in your context?
Subjective and Context Sensitive!
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Quality attributes of Software Architecture
the end [email protected]
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