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bok:eng:mbse:intro [2020/07/05 09:18] anwlur [Performance Qualities] added more metrics |
bok:eng:mbse:intro [2020/09/11 12:19] (current) anwlur [Parts] fixed internal link |
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| ===== Performance Qualities ===== | ===== Performance Qualities ===== | ||
| - | Metrics improve development process, understanding of complexity, discovering/predicting faults and estimation of efforts. Often the choice of metrics exceed what is required and therefore it is advised to define what is the purpose of measurement. | + | See this page on [[bok:eng:mbse:quality|model quality]]. |
| - | ==== Framework for Deciding Metrics ==== | + | See this page on how to [[bok:eng:mbse:critique|critique a model]]. |
| - | A useful framework to derive useful metrics is the Goal-Question-Metric (GQM) paradigm developed by Basili [2]. The GQM process is as follows: | ||
| - | - Define goals of measurement (for "UML As Sketch" type models then goal is mainly focusing on communication.) | ||
| - | - Define questions that have answer that allow the observer to determine whether the goal has been met | ||
| - | - Each question is evaluated to determine what metrics are required to support the question's answer. | ||
| - | |||
| - | ==== Quality Goals ==== | ||
| - | |||
| - | Mohagheghi [1] show that there are 6 classes of quality goals for models: | ||
| - | * Comprehensibility (emphasis for model sketches) | ||
| - | * Confinement (emphasis for model sketches) | ||
| - | * Correctness (emphasis for model design) | ||
| - | * Completeness (emphasis for model design) | ||
| - | * Consistency (emphasis for model design) | ||
| - | * Changeability (emphasis for model design) | ||
| - | |||
| - | {{ :bok:eng:mbse:intro:mbse_intro1.png?400 |}} | ||
| - | |||
| - | * **Comprehensibility** - Model is understandable to its intended audience. | ||
| - | * **Confinement** - Model is in agreement with its purpose | ||
| - | * **Correctness** - Model includes correct elements & relationships. Does not violate rules and conventions | ||
| - | * **Completeness** - All necessary information is included at the necessary degree of fidelity | ||
| - | * **Consistency** - Model is without contradictions. //Horizontal consistency// is consistency between diagrams and views that belong same level of abstraction. //Vertical consistency// is consistency between models or diagrams at different levels of consistency. Consistency also refers to semantics, i.e. same element does not have multiple interpretations | ||
| - | * **Changeability** - Model supports continuous and rapid improvement and evolution | ||
| - | |||
| - | MIT xPRO propose the following "Qualities of Great Models" | ||
| - | * Linked to Decision Making. | ||
| - | * Model Credibility - it is believable | ||
| - | * Clear Scope | ||
| - | * Verification and Validation of Model - Model should show why it is the preferred option to do verification and validation of the system | ||
| - | * Traceable and Analyzable | ||
| - | * Understandable and Well Organized | ||
| - | * Data extrapolation - where is the model valid | ||
| - | * Complete relative to Scope | ||
| - | * Internally consistent | ||
| - | * Verifiable | ||
| - | * Validatable | ||
| - | * Elegant | ||
| - | * Appropriate level of Fidelity | ||
| - | * Allows Optimization - does it includes gradients or convexity | ||
| - | * Avoid optimization on a black box | ||
| - | * Reuse | ||
| - | * Availability of Interfaces | ||
| - | |||
| - | ==== Model Metrics ==== | ||
| - | |||
| - | * **Model Size** - number of elements[3]. Allows for | ||
| - | * Comparison of models (before and after, model A and model B on same system) | ||
| - | * Measure of progress | ||
| - | * Prediction of work effort | ||
| - | * **Design Metrics** | ||
| - | * Degree of coupling between classes (e.g. number of interactions within a class) | ||
| - | * Degree of inheritance (e.g. depth of inheritance) | ||
| - | * Degree of cohesion | ||
| - | * Degree of polymorphism | ||
| - | * Degree of information hiding | ||
| - | * Degree of complexity | ||
| - | * **Comprehensibility Metrics** | ||
| - | * Number of elements on diagram | ||
| - | * Number of crossing lines on diagram | ||
| - | * Number of entry and exit points on diagram | ||
| - | |||
| - | ==== References ==== | ||
| - | |||
| - | * [1] P. Mohagheghi et al, [[https://www.omg.org/ocsmp/ICSE2009_WoSQ_3415_mohagheghi_parastoo.pdf|"Existing Model Metrics and Relations to Model Quality"]] Accessed on Jul. 4th, 2020 | ||
| - | * [2] V.R. Basili, G. Caldiera, and H.D. Rombach, "The Goal Question Metric Paradigm", In Encyclopedia of Software Engineering, volume 2, John Wiley and Sons, 1994, pp. 528-532. | ||
| - | * [3] C.F.J. Lange, [[http://www.win.tue.nl/~clange/papers/Lange_ModelSizeMatters.pdf|"Model Size Matters"]], Proc. Model Size Metrics Workshop, 2006. | ||
| ===== Problem ===== | ===== Problem ===== | ||
| {{ :bok:eng:mbse:intro:week_03_still_03_b.jpg?600 |}} | {{ :bok:eng:mbse:intro:week_03_still_03_b.jpg?600 |}} | ||
| Line 139: | Line 73: | ||
| ===== Methodology ===== | ===== Methodology ===== | ||
| + | For a review of MBSE Methodologies see this [[bok:eng:mbse:method|page]]. | ||
| ==== Method ==== | ==== Method ==== | ||
| Line 154: | Line 89: | ||
| === MBSE activity === | === MBSE activity === | ||
| + | * Ask questions | ||
| + | * Why model? | ||
| + | * What problem are we trying to solve with the model? | ||
| * Evaluate what functions (and at what level of fidelity) MBSE activity should be applied to | * Evaluate what functions (and at what level of fidelity) MBSE activity should be applied to | ||
| * Evaluate what components (and at what level of fidelity) MBSE activity should be applied to | * Evaluate what components (and at what level of fidelity) MBSE activity should be applied to | ||
| Line 198: | Line 136: | ||
| * Use Cases | * Use Cases | ||
| * Nominal Scenarios - covers basic outcomes under nominal conditions and does not consider exceptions | * Nominal Scenarios - covers basic outcomes under nominal conditions and does not consider exceptions | ||
| - | * [[mbse:critique|Critique]] | + | * [[bok:eng:mbse:critique|Critique]] |
| ===== Use Cases ===== | ===== Use Cases ===== | ||
bok/eng/mbse/intro.1593940728.txt.gz ยท Last modified: 2020/07/05 09:18 by anwlur
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