Model-Driven Development Definitions, Challenges, Promises…

Talking Points  What is Model-Driven Development?  What is Difficult with Real-time & Embedded Systems?  Why does MDD™ often Fail?  What enables MDD™?  Comments on Various MDD Enablers  What is MARTE™?  When will MDD™ Succeed?  Concluding Remarks and Hand-over to the MARTE Examples Talk.

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What is a Model?  Noun: from Latin modellus, diminutive form of modulus ‗small measure‘[1].  A simplified representation (usually mathematical) used to explain the workings of a real world system or event. − ―The computer weather model did not correctly predict the path of the hurricane.‖  The structural design of a complex system. − ―The team developed a sound business model.‖

 A praiseworthy example to be copied, with or without modifications − ―British parliamentary democracy was seen as a model for other countries to follow‖ © 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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What is Development?  Noun: development[2]  The application of new ideas to practical problems − ―Our development department has produced three new adhesives this year.‖  The active placement of the pieces, or the process of achieving it − ―White's development is good, but Black's has been hampered by the pawn on e5.‖

 QED: An active process of problem-solving via analysis and synthesis of alternatives…

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What is Model-Driven Development?  The ―rapid solutioning‖ of complex systems from Models which are smaller and more abstract than are those synthesized systems − Models which are larger and more complex than their solutions suggests something has gone wrong!

 The solving of problems using Models pervasively and using Models as the inputs to parameterized implementation generators  Development Methodologies which regard Models as the Intellectual Property − Rather than those which (or who) regard the output artifacts as irreplaceable

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Why is Real-Time and Embedded Development Different?  Solutions are constrained by Time, Space, Cost, and Access  Consequences of failure include − Loss of Revenue − Loss of Systems − Loss of Life  Verification by Inspection, Demonstration, or Test can be impractical − Leaving just Verification by Analysis

© 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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Why does Model-Driven Development Fail?  Models are Incomplete

 Model Development is too slow

 Models are Inconsistent

 Graphical Grammars are no more— or are less—expressive than Text

 Models are Ambiguous  Models are Incomprehensible  Models are Unsharable  Models are Unverifiable  Models Ignore Multiform Time

 Models lack Quantitative and Qualitative Metrics

 Modeling Tool User Interfaces are User Hostile  Modeling Tools are Buggy  Good Modeling is Subjective  Models are Cohesive, Coupled, Complex, Rigid, and Fragile − Like the epitome of bad code…

 Model Development is too arduous © 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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What Enables Model-Driven Development?  Standardized Methodologies − Collections of Methods and Processes − Objective Metrics

 Standardized Syntax, Notations, Symbols  Standardized Semantics  ―Models of Computation‖  Multiform Time  Formal Methods

 Interfaces, Design by Contract  Variation and Sensitivity Analysis  Tradeoffs Analysis  Provers and Solvers  Collaboration  Isolated Modeling  Change Management

 Workflow Integration  Design for Test

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Quantitative Model Metrics  Number of Requirements? Use Cases? Classes? SysML Blocks? − 5 are too few, 100,000 are too many—but are 500 just right?  Number of Diagrams?  Number of Steps per Interaction Diagram?  Number of Packages?  Number of elements per Package?  Number of Associations?  Currently, No Set of Objective, Quantitative Metrics

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Qualitative Model Metrics  Requirements have been Refined? Derived? Satisfied? Verified?  Use Cases have Interaction Diagrams?  Model has a Package Structure supporting IPTs? Collaboration? Component Sharing? Multiple Programming Languages?  ―Evil Twins‖ are not Present?  Diagrams have White Space? Are Pretty? Have Comments?  Model has internal Documentation?  Model uses Design Patterns?

 Model expresses Tradeoffs and Rationales?  Model is Executable? Verifiable? Reusable?  Currently, No Set of Objective, Qualitative Metrics © 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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Standardized Symbols and Notations  Alphabets and Grammars (but not Sentences)  Mathematical Expressions  Mathematical and Logical Symbols  Set Theory  Predicate Calculus  Query and Constraint Languages  Domain-specific Engineering Notations − Control, SCADA, HVAC, Electrical, Building, UML, MARTE…  Standardized Symbols Facilitate Comprehension © 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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Domain-Specific Modeling  Specific versus General Modeling  Ideally More Abstract and More Expressive  Offers Reduction in Effort  Stylized Icons  Business Logic Constraint Enforcement  Approachable in UML™ with − Stereotypes − Tag Definitions − Tool Behavior Modification via plugin Scripting

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Formal Methods  Mathematically rigorous Techniques and Tools for − the Specification, Design and Verification of Software and Hardware[3]  Systemic Usage yields Verifiable Systems Throughout Lifecycle  Example Languages − Esterel and Lustre − Vienna Development Method – Specification Language (VDM-SL) − Temporal Logic of Actions (TLA+) − Z(ed)

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Interfaces and Contracts  Interfaces − Delegate Interactions − Separate Specification from Implementation − Decouple Components − Enable Dynamic Substitution − Enables Mocking for Testing − Examples: − Provided and Required Interfaces − Abstract Classes

 Contracts − Express Preconditions and Postconditions − Enable formal Verification − Exploitable throughout the System Specification and Implementation

 Contracts, written in Formal Methods, are especially powerful − Examples: − Spark Ada − Eiffel

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Model Transformations  takes as input a model conforming to a given metamodel and produces as output another model conforming to a given metamodel. …One of the characteristics of a model transformation is that a transformation is also a model[4]  Frequently only unidirectional

− Model-to-text or ―Code Generation‖  Powerful when bidirectional − Traceable and Reversible − E.g. Triple Graph Grammars

 Automated Transformations − Replace lengthy, error-prone manual transformations − E.g. the Eclipse ATLAS Transformation Language (ATL) © 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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Model to Text Transformations  Traditionally: ―Code Generation‖  Also: Document Generation, Testcase Generation, XMI, etc.  Typical Methods − Model(s) → Query → XMI → XSLT → Formatted Output − XMI → ATL → XMI → XSLT → Formatted Output − Model(s) → Query → Configurable Procedures → Formatted Output − Model(s) → Query → Parameterized Templates → Formatted Output

© 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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Design Patterns

 A general, repeatable solution to a commonly occurring problem in software design…  Not a finished design that can be transformed directly into code…  A description or template for how to solve a problem that can be used in many different situations.[5]

 Creational

−

Mediator

−

Factory

−

Observer

−

Singleton

−

State

−

Strategy

−

Template Method

−

Visitor

 Structural −

Adapter

−

Decorator

−

Façade

−

Proxy

 Behavioral −

Broker

−

Chain of Responsibility

−

Command

−

Iterator

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 Concurrency −

Active Object

−

Scheduler

−

Thread Pool

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Models of Computation  Offer Design Patterns of Component Interaction[6]

 Component Interaction

 Express Semantics of Concurrency and Time

 Communicating Sequential Processes

 Often Derived from Formal Mathematics  No panacea ―MoC‖ − Foreach ―MoC‖ − Useful when Circumstances are Suitable

− e.g. CORBA

− E.g. Hoare, Occam

 Discrete-Event − E.g. Digital Hardware Simulation

 Synchronous Dataflow − E.g. Streams and Signal Processing

 Synchronous/Reactive − E.g. Esterel/Lustre

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Collaboration and Isolation  Engineering Activities are either − Collaborative − Isolated  Collaborative when

− Brainstorming, Sharing, Presenting, Concurrent − E.g. Systems Engineering  Isolated when − Rapidly Prototyping, Refactoring, Analyzing, Verifying, Serialized

− E.g. Software Engineering  MDD Methodologies and Tools must Enable both forms of Engineering − But most don‘t… © 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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Collaboration and Workflow  Common, Referentially Consistent ―Data‖ Dictionary  Automatic Publication of − Who Changed What − Why and When

− In the larger Context  Management of Such Change − Historical Variations − Differencing − Reversion Ability  Individual-centric Models and Manual Change Propagation impede MDD

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Rapid Prototyping  Software (or Solid Form) Feature Implementation  Small Subset of Features  May be significantly different from Final Implementation  Enables Early Assessment

 Requires an easily mutable modeling medium (like Text in Vi ) − Any rigid, coupled, time-consuming model would be an impediment  Requires isolated not collaborative engineering − Mutual exclusion from conflicting, radical modifications  MDD Methodologies and Tools must Enable both forms of Engineering − A few do…

© 2008 Artisan Software Tools Ltd. All rights reserved. 15 June 2008 OMG::Washington, DC::VanZandt

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Analysis  Noun: From Medieval Latin analysis from Ancient Greek ἀνάλυσις (analusis) from ἀναλύω (analuō), ―‗I unravel, investigate‘‖) from ἀνά (ana), ―‗on, up‘‖) + λύω (luō), ―‗I loosen‘‖)[7]  The action of taking something apart in order to study it.

 The mathematical study of functions, sequences, series, limits, derivatives and integrals.  The process of breaking a substance down into its constituent parts.  QED: Understanding a System by tearing it apart and studying the pieces

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Simulation  Substitution for Analysis when Closed-Form Solutions aren‘t achievable  Enables Analysis by Execution  Enables Solvers, Provers, Tradeoff and Sensitivity Analysis  Without Requiring Actual Environment or System  In Compressed or Expanded Absolute Time  Requires Workload Specifications  Requires Non-Functional Property Value Specifications  Requires Instances Specifications  Requires Integrated Modeling and Simulation Tools

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Unit Testing and Mocking  Testable Units (Packages of Models) −

Can be verified, trusted, reused earlier

 But, Embedded Systems are Often −

Highly Coupled

−

Intrinsically Complex

−

Difficult to Decompose into Individually, Testable Units

 Interfaces and Mocks enable Scriptable, Mocking Test Harnesses to −

provide Required services

−

Record interaction and coverage

−

Respond with proper Sequences

−

Detect missing Expected Interactions

 UML Testing Profile offers Standardized Verification Modeling  MDD™ Requires Modular Models to Enable Unit Testing

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History of MARTE™  Spawned from RT/E Software Engineers‘ Frustration with the Inability to Express, Analyze, and Simulate Time and Resource Constrained Systems − In any way other than implementing prototypes, executing those, and observing their behavior

 Motivated by the Inadequacies of the prior OMG Profile for Schedulability, Performance, and Time (SPT)  Launched in Feb 2005 with the ProMARTE RFP Response[8]  Adopted Specification as of May 2008

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Foundations of MARTE™  Non-Functional Properties − Qualities − Value Specification Language  Time

− Multiform Models of Time and Events − Causal, partial ordering − Clocked, synchronous

− Absolute and Relative Physical Time

 Generic Resource Modeling − Execution Platform  Generic Component Modeling − Compositions

− SysML™ Blocks − Interfaces, Flows, and Interactions  Allocations

− Spatial Deployment − Temporal Scheduling − Based upon SysML™ Allocation

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Using MARTE™ for Design  Software Resource Modeling  Hardware Resource Modeling  Real-time Embedded Models of Computation and Communication

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Using MARTE™ for Analysis  Generic Quantitative Analysis Modeling  Schedulability Analysis Modeling  Performance Analysis Modeling

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When MDD™ Will Succeed  Refinement of de facto Metrics − Completeness, Objectivity  Adoption of Formal Methods − Completeness, Consistency, Verification  Improvement of Tools

 Additional Research − Graphical Expressiveness − Metrics  Improved Education − Consistency, Modeling Fluency, Objectivity

− Consistency, Collaboration, Modeling Fluency, Modeling Duration, User Interfaces, Model Modularity

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References 

[1] Wiktionary Contributors., "Wiktionary Definition of "Model"." Wiktionary: a wiki-based Open Content dictionary. [Online] May 29, 2008. [Cited: June 14, 2008.] http://en.wiktionary.org/w/index.php?title=model&oldid=4661990.



[2] —. "Wiktionary Definition of "Development"." Wiktionary: a wiki-based Open Content dictionary. [Online] June 05, 2008. [Cited: June 14, 2008.] http://en.wiktionary.org/w/index.php?title=development&oldid=4691164.



[3] Butler, Ricky W., "What is Formal Methods?" Langley Formal Methods. [Online] August 06, 2001. [Cited: June 13, 2008.] http://shemesh.larc.nasa.gov/fm/fm-what.html.



[4] Wikipedia Contributors., "Model Transformation." Wikipedia, The Free Encyclopedia. [Online] October 03, 2007. [Cited: June 15, 2008.] http://en.wikipedia.org/w/index.php?title=Model_transformation&oldid=139650456.



[5] —. "Design Pattern (Computer Science)." Wikipedia, The Free Encyclopedia. [Online] October 03, 2007. [Cited: June 15, 2008.] http://en.wikipedia.org/w/index.php?title=Design_pattern_%28computer_science%29&oldid=161755559.



[6] Lee, Edwards, et al., "Overview of the Ptolemy Project." Department of Electrical Engineering and Computer Science. [Online] July 02, 2003. [Cited: June 15, 2008.] http://www.ptolemy.eecs.berkeley.edu/publications/papers/03/overview/overview03.pdf. Technical Memorandum UCB/ERL N03/25.



[7] Wiktionary Contributors., "Wiktionary Definition of "Analysis"." Wiktionary: a wiki-based Open Content dictionary. [Online] May 23, 2008. [Cited: June 15, 2008.] http://en.wiktionary.org/w/index.php?title=analysis&oldid=4625313.



[8] ProMARTE Team., "UML Profile for MARTE RFP." MARTE Specification. [Online] February 04, 2005. [Cited: June 11, 2008.] http://www.omg.org/docs/realtime/05-02-06.pdf. realtime/05-02-06.

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Speaker Biography  Lonnie VanZandt  Artisan Software Partner; Artisan Studio® user since 2000  Independent Consulting Systems Engineer (Predictable Response Consulting) since 2000  Specialties include: Operating Systems kernels, Real-time Systems, Object Oriented Systems, Network Protocols, UML™ Modeling, Artisan Studio® Usage, Together© Usage  Career includes: AT&T Lucent Bell Labs, TimeSys Linux, Northrop Grumman {Cleared}, DesignNet, …  Education: BS and MS, Computer Engineering, University of Illinois, Urbana

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Copyright Notices  UML™, OMG™, MDA™, MDD™, SysML™, MARTE™, and the OMG MDA Logo are either registered trademarks or trademarks of Object Management Group, Inc. in the United States and/or other countries.  Artisan Studio® and the Artisan Studio® Logo are either registered trademarks or trademarks of Artisan Software Tools Ltd. in the United States and/or other countries.  Each slide within this presentation is Copyright © 2008 Artisan Software.

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