Software Quality: Hitting a Moving Target

Transcription

1 Software Quality: Hitting a Moving Target Prof. Dr. Dieter Rombach Dr. Adam Trendowicz Tokyo, February 19, 2015 Fraunhofer IESE Fraunhofer-Platz Kaiserslautern Germany dieter.rombach@iese.fraunhofer.de adam.trendowicz@iese.fraunhofer.de

2 Joseph von Fraunhofer ( ) Researcher Discovery of the Fraunhofer lines in the solar spectrum Inventor Development of new methods for lens processing Entrepreneur Director and partner in a glass manufactory Deutsches Museum Fraunhofer-Gesellschaft Fraunhofer Lines 2

3 Fraunhofer Institute for Experimental Software Engineering Founded in 1996 One of the leading software engineering institutes in Europe and worldwide Over 200 employees Itzehoe Rostock Lübeck Bremerhaven Bremen Hannover Potsdam Berlin Teltow Braunschweig Magdeburg Cottbus Oberhausen Dortmund Halle Schkopau Leipzig Duisburg Schmallenberg Dresden St. Augustin Jena Aachen Euskirchen Chemnitz Wachtberg Ilmenau St. Ingbert Saarbrücken Karlsruhe Pfinztal Ettlingen Stuttgart Darmstadt Würzburg Erlangen Kaiserslautern Fürth Freiburg Kandern Efringen- Kirchen Nürnberg Freising München Holzkirchen 3

4 Our Formula for Your Success 4

5 Core Competencies of Fraunhofer IESE ES/CPS Smart Ecosystems IS/Mobile SOFTWARE-ENABLED INNOVATIONS 5

6 Customized Services for You GQM + Strategies : Aligning IT Strategies and Business Goals Software Quality: Hitting a Moving Target 6

7 Software Quality Why should I care? Software quality is a critical success factor Quality is the best business plan J. Lasseter (co-founder of Pixar Animation) Quality makes the difference Quality is what may differentiate our product on the market Once spoiled, quality is hard and expensive to fix By the time you figure out you have a quality problem, it is probably too late to fix it. John S. Reel 7

8 Quality in Theory The ilities are good for management talk. I know quality when I see it! 8

9 Quality in Practice How the customer explained it How the project leader understood it How the analyst designed it How the programmer implemented it What the beta tester received What the customer really needed How the business consultant described it Quality = Fitness for Use User Satisfaction How the project was documented What operations installed How it was supported How the customer was billed Paragon Innovations, Inc

10 Software Quality A Moving Target Concept Quality User Satisfaction Moving Target Definition Quantification Usability Maintainability Depends on: Object Quality Focus Perspective Context Customer Software Quality Code Supplier Reliability Portability 10

11 SPECIFY QUALITY ASSESS IMPROVE 11

12 Software Quality Quality Modeling What does Quality mean to the customer? Developer V&V Tester How does customer s view translate into product-, process-, and resource properties? Quality Model Is Quality acceptable? Customer/ User QualityModel IV&V / Certification Authority 12

13 Specifying & Assessing Software Quality: A Car Analogy Overall Assessment Aggregation Subjective Ratings Objective Ratings Attributes [from ADAC Autotest, August & September 2013] 13

14 Example Challenges of Quality Modeling Multidimensional Nature of Quality Quality Focus Entities Instances Maintainability Complexity Size Design Code Method 1 Method 2 Quality attributes hierarchy Abstract: quality aspects and subaspects Concrete: properties of entities (factors) Object hierarchy Entity: type or class of a software product Instance: particular software product; instance of the same entity Measures Cyclomatic Complexity E N P CC = E N + 2P Halstead s Science E - #edges N - #nodes P - #connected components (exit nodes). Measurement hierarchy Base measures Derived measures 14

15 Maintainability Model BMW Car IT Z 2: Software Maintainability a b c d Q 1: Analyzability Q 2: Adaptability Q 3: Stability Q 4: Testability a b c d e a b c d a 2 a b c Goal ISO9126 Quality Focus Question Groups Metric Weights Relationships S 1: Documentation 1 F 2 C 1 + J... S 2: Internal Complexity S 5: Generation 1 F 2 C S 6: Reuse 4 F 4 C 2 + J... S 7: Testing 1 F 2 C 2 + J... 1 LOC F... 2 CC + J S 3: Coupling 1 F S 4: Nesting 2 F 3 + J... 3 C 3 C J J Assessment Example Comparison Sys1 Sys2 Q 1: Analyzability 3,72 1,89 Q 2: Adaptability 4,47 1,33 Q 3: Stability 3,67 2,33 Q 4: Testability 3,80 2,10 Z 2: Maintainability 3,98 1,80 Evaluation Scale 5 = good maintainability 1 = bad maintainability 15

16 Quality of Safety-Critical Software Systems JAXA Safety Analysis (e.g., FTA) Subsystem A System Structure Subsystem A C1 C2 f1 f2 f3 C f4 f5 f6 7 8 Q 1: Analyzability S 3: Coupling S 1: Documentation 1 FIN_S 1 1 GUIDEPLOC COM S 2: Internal Complexity 1 aveloc 1 CCPF FOUT_S CBOPM avedc Quality Model Visualization (e.g., 3D Tree Maps) 16

17 Proactive Management of Quality Debt Quality Quality Aspects Software Metrics Quality Model Q1 Q2 Q3 Q4 Target Quality Gap Current Quality Profile Product Manager Acceptance Threshold Cost Time T 0 T 1 T 2 T 3 Software Products Cost of Quality Gap 17

18 Takeaways Quality is relative and depends on the context The stakeholders involved and their needs The objects considered and their characteristics Quality must be specified explicitly in order to be controlled Existing standards (such as ISO 25000) are too generic Quality models must be adapted to company specifics Link to higher-level goals and process integration should be clarified when assessing quality Proper tool support needs to be established in order to reduce overhead 18

19 Dōmo arigatō どうもありがとう Dr. Adam Trendowicz Senior Engineer Process Management PM Fraunhofer IESE Fraunhofer-Platz Kaiserslautern Germany Phone: +49 (0) Fax: +49 (0) adam.trendowicz@iese.fraunhofer.de 19