UML as a Programming Language

UML® as a Programming Language

Ed Seidewitz

Presented at the

Vienna University of Technology

3 December 2014

Copyright © 2014 Ed SeidewitzUML® is a registered trademark of the Object Management Group

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Developers provide feedback to the architects (maybe)

Modeling is extra work (isn’t it?)

It is hard to validate the correctness of the models before development.

The developers may not follow the models, without providing feedback.

It is hard to keep the models and development artifacts in sync during development (and maintenance).

Architects give models to developers

Developers create artifacts based on the models(maybe)

Architects create the models

Copyright © 2014 Ed Seidewitz 2

There are two responses

1. Code-based developmentUse models for initial design, but then focus on code

Pro: Code is single source of “truth”

Con: Code is not as good for expressing design as models.


There are two responses

2. Model-driven developmentUse models as the source artifacts for development

Pro: Models can be more easily understood and evolved by human developers and maintainers.

Con: Model must be detailed enough to be executable in its own right.

But is this really a “con”??


The question Is…

If we are going to take the time to carefully design our system using UML

Structural models

Behavioral models

Then why can’t we use these directly to execute our system


The answer is…we can!

Just add detailed behavior

But...Making models detailed enough for machine execution defeats the purpose of models for

human communication.

Executable models can still be more understandable than executable code.

(Non-executable models are still useful, too.)



UML is not specified precisely enough to be executed (at least not in a standard way).


But...

The Foundational UML (fUML) standard specifies precise semantics for an executable subset of UML.



Graphical modeling notations are not good for detailed programming.


But...

The Action Language for fUML (Alf) standard specifies a textual action language with fUML semantics.


Example: Property Management SOA

Graphical UML notation for

Data model

Message model

Interface and class models

Component models

Textual Alf notation for

Operation methods


Property Data Model


Service Request Message Model


Service Reply Message Model


Service Interface and Implementation


Service Provider Component


Composite structure and ports are not in fUML, but

they are in the Precise Semantics of Composite

Structure (PSCS) extension.

Operation method: establish


/** Establish a new property record. */

activity establish (

in request: 'Property Record Establishment',

out reply: 'Property Management Success Reply' [0..1],

out error: 'Error Reply' [0..1] ) {

identifier = this.'property identifier factory'.'get next identifier'();

if (request.'property type' == 'Property Type'::personal) {

property = new 'Personal Property'::'create property'(identifier,request.name);

} else {

property = new 'Real Property'::'create property'(identifier,request.name);

}

reply = this.'create reply'(request.identifier, property);

}

Operation methods are specified as UML

activities.

Newly created objects persist at the current

execution locus.

Names can have spaces or other

special characters.

Operation method: update


/** Update the data of a property other than acquisition or disposition. */

activity update (

in request: 'Property Record Update',

out reply: 'Property Management Success Reply' [0..1],

out error: 'Error Reply' [0..1] ) {

property = Property -> select p (p.identifier == request.'property identifier');

if (property -> isEmpty()) {

error = new 'Error Reply' (

identifier => request.identifier + "/error",

'request identifier' => request.identifier,

'error code' => "PRU-001",

'error message' => "Property not found." );

} else if (property.status == 'Property Type'::disposed) {

…

} else {

if (request.'property location' -> notEmpty()) {

location = Location -> select loc

(loc.identifier == request.'property location');

'Property Location'.createLink(property, location);

}

…

}

}

A “select” maps to a concurrent expansion

region over a class extent.

Creating a link automatically establishes a bidirectional

relationship.

The models are validated in a development/test environment

We can program in UML!

The models are deployed in a production environment

Developers create fully executable models

Developers iteratively execute, test and update the models


Agile development…with executable models!

But why UML?

UML…

Allows abstractions closer to theproblem domain

Is already familiar to developers fordesign

Has widely available tooling

© 2014 Ed Seidewitz 18

Multi-core processing is the future

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10

100

1 000

10 000

100 000

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10 000 000

1975 1980 1985 1990 1995 2000 2005 2010

Transistors(1000s)

Clock (MHz)


Why is multi-core hard?

Traditional processor architectureSingle processor

Local registers / cacheRemote memory

Traditional programming languageFunctions / proceduresLocal variables / stack

Heap memory

Traditional modeling languageThings / Relationships

Events / BehaviorsCommunication

Automaticcompilation

Humanimplementation


Why is multi-core hard?

Traditional processor architectureSingle processor

Local registers / cacheRemote memory

Traditional programming languageFunctions / proceduresLocal variables / stack

Heap memory

Traditional modeling languageThings / Relationships

Events / BehaviorsCommunication

Multi-core processor architectureMany processors

Much local memoryGlobal memory (?)

Concurrency is natural here

Concurrency is natural here

Concurrency is NOT natural here!


from Oracle presentation “Divide and Conquer Parallelism with the Fork/Join Framework”

What makes it easier?

Result solve(Problem p) {if (p.size() < SEQUENTIAL_THRESHOLD

{ return p.solveSequentially();

} else { Result left, right; INVOKE-IN-PARALLEL { left = solve(p.leftHalf()); right = solve(p.rightHalf());

} return combine(left, right);

}}

Pseudo-codeDivide and conquer (fork/join)


from Oracle presentation “Divide and Conquer Parallelism with the Fork/Join Framework”




} else { Result left, right; INVOKE-IN-PARALLEL { left = solve(p.leftHalf()); right = solve(p.rightHalf());


}}

class SolutionTaskextends

RecursiveAction {Problem p;SolutionTask(

Problem p) {…}void compute() {SolutionTask left =

new SolutionTask(…);SolutionTask right=

new SolutionTask(…);

invokeAll(left, right);

JavaDivide and conquer (fork/join)





} else { //@parallel{ left = solve(p.leftHalf()); right = solve(p.rightHalf());


}}

solve(in p: Problem): Result {Alf UML

«structured»

«structured»

«structured»

Divide and conquer (fork/join)


What makes it easier?Bulk data (select/map/reduce)

data->select x (filter(x))->collect x (map(x))->reduce combine

Alf

map

«parallel»

filter

«parallel»

«reduce»combine

UMLCopyright © 2014 Ed Seidewitz 25

What makes it easier?Asynchronous objects (actors)

GetAuthorization

ChargeApproved

new CreditCardCharge

ChargeApprovedChargeDenied


But why UML?

Why not

Clojure

Scala F++

HaskellErlang

These all require new ways of thinking about coding

…


But why UML?

UML…

Allows abstractions closer to theproblem domain

Is already familiar to developers fordesign

Has widely available tooling


Deals with concurrency in the

UML as a Programming Language


LieberLieber AM|USE for Sparx Enterprise Architect

http://www.lieberlieber.com/model-engineering/amuse

NoMagic Cameo Simulation Toolkitfor MagicDraw

https://www.magicdraw.com/simulation

Moka Model Execution Enginefor Eclipse Papyrus (open source)

https://wiki.eclipse.org/Papyrus/UserGuide/ModelExecution

http://www.lieberlieber.com/model-engineering/amuse

https://www.magicdraw.com/simulation

https://wiki.eclipse.org/Papyrus/UserGuide/ModelExecution

UML as a Programming Language


fUML Open Source Reference Implementationhttp://fuml.modeldriven.org

(see also http://www.modelexecution.org)

Alf Open Source Reference Implementationhttp://alf.modeldriven.org

Unified Modeling Languagehttp://www.uml.org

Ed [email protected]

@seidewitz

http://fuml.modeldriven.org

http://www.modelexecution.org

http://alf.modeldriven.org

http://www.uml.org

mailto:[email protected]

UML as a Programming Language

Software

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