Olivier Le Goaërolivier.legoaer@univ-pau.fr

Séminaire LIRMMMontpellier, 30/09/2016

Executable modeling Executable modeling &&

dynamic adaptation dynamic adaptation

2/31

A short bioA short bio

Positions● Ph.D in 2009 – AeLoS team, LINA

● Associate Professor since 2010 – MOVIES team, LIUPPA

Research topics● Software Evolution/Adaptation

● Software Architecture

● Model-Driven Engineering

Hobbies● Mobile technologies

● Web technologies

3/31

Domain-specific languages (DSL)Domain-specific languages (DSL)

General Purpose Languages● Not targeted to a particular kind of problem, but to any kinds of

software problem

Domain-Specific Languages● Targeted to a particular kind of problem

– with dedicated notations (textual or graphical), support (editor, checkers, etc.)

● Promises: more « efficient » languages for resolving a set of specific problems in a domain

● Each concern described in its own language– For software developpers (modeling, programming, querying, building,

documenting, ...), for software architects (ADL), for statisticians (R), for biologists, for sociologists, ...

4/31

Shapes for a DSLShapes for a DSL

Internal● Hosted by a

GPL

External● Stand-alone

Implicit● API-like

C# & Linq SQL Querydsl SQLJava API

QCustomer customer;customer = new QCustomer("c");

SQLQuery<?> query = new SQLQuery<Void>(connection);

List<String> lastNames = query.select(customer.lastName) .from(customer) .where(customer.firstName.eq("Bob")) .fetch();

System.out.print(lastNames);

SELECT lastNameFROM customerWHERE firstName = 'Bob';

var queryBobCustomers = from cust in customer where cust.firstName == "Bob" select cust.lastName;

foreach (var n in queryBobCustomers){ Console.WriteLine(n);}

5/31

Shapes for a DSLShapes for a DSL

Internal● Hosted by a

GPL

External● Stand-alone

Implicit● API-like

C# & Linq SQL Querydsl SQLJava API

QCustomer customer;customer = new QCustomer("c");

SQLQuery<?> query = new SQLQuery<Void>(connection);

List<String> lastNames = query.select(customer.lastName) .from(customer) .where(customer.firstName.eq("Bob")) .fetch();

System.out.print(lastNames);

SELECT lastNameFROM customerWHERE firstName = 'Bob';

var queryBobCustomers = from cust in customer where cust.firstName == "Bob" select cust.lastName;

foreach (var n in queryBobCustomers){ Console.WriteLine(n);}

6/31

Models are taking a new roleModels are taking a new role

« marauders map » – Harry Potter

Model playing a static role (design-time)

Model playing a dynamic role (run-time)

● Tells us about the structure of the castle (every classroom, every hallway, and every corner)

● Tells us about moving persons (shows foot prints)

7/31

Crossing the demarcation lineCrossing the demarcation line

Model of a system(conforms to a metamodel)

S

Running system

INTERPRETATION

Running system=

model under execution

Design-time

Run-time

COM

PILAT

ION

</xml>

sub{ }MDA ®

MM

exec(M)exec(M)

8/31

Executable modeling (xModeling)Executable modeling (xModeling)

Compilation● Translational semantics

– Code generation in a target language

Direct execution (~VM/interpreter)● Operational semantics

– Using an « action » language

– Using a M2M transformation (rare in practice)

Breathing life into models● Simulation, V&V, rapid prototyping...

● Ultimately, skip the implementation stage !

9/31

Controversies and debatesControversies and debates

Executable models "can be run, tested, debugged, and measured for performance"

UML / fUML as prominent examples● Is a class diagram executable? Alone ?

● Is a paquage diagram executable?

● Is a sequence diagram executable?

Raises the question of an executable nature● Behavior of a software system captured by a model M

● Ability to define a current execution state within M

● Ability to compute the next state (aka « step ») within M

10/31

xModeling built with MDExModeling built with MDE

Meta-models are just a specific OO data structures to represent abstract syntax trees● Operational semantics = computation steps and runtime data

● A VM/interpreter is a program working with such AST and that implements a given operational semantics

Executable metamodeling● xMOF (eXecutable MOF)

● Kermeta

● Ecore + body of operation(s) written Java/EMF

● …

11/31

xModeling's componentsxModeling's components

Abstract Syntax

Metamodel +

Well-formedness rules

Concrete Syntax

Graphical or textual

Semantics

How it behaves at runtime ?

12/31

Modeling with StatechartsModeling with Statecharts

--The instance of the finite state machine is unique (root)context StateMachine inv singleStateMachine: StateMachine.allInstances()->size() = 1 and self.container.oclIsUndefined()

--All the states are included in composites except the finite state machine herselfcontext State inv containerForAllStates: not self.oclIsTypeOf(StateMachine) implies not self.container.oclIsUndefined()

13/31

Train Cruise Control ModelTrain Cruise Control Model

14/31

xModeling with Statecharts xModeling with Statecharts

runToCompletion()

isActive:boolean

0..1

lastKnownActiveState

-- When an history state exists and references a state, the latter must belongs to the compositecontext CompositeState inv historyInComposite: if self.historyState.oclIsUndefined() then true else if self.historyState.referencedState.oclIsUndefined() then true else self.states->includes(self.historyState.lastKnownActiveState) endif endif

15/31

xModeling with Statecharts xModeling with Statecharts

runToCompletion()

isActive:boolean

0..1

lastKnownActiveState

-- When an history state exists and references a state, the latter must belongs to the compositecontext CompositeState inv R3: if self.historyState.oclIsUndefined() then true else if self.historyState.referencedState.oclIsUndefined() then true else self.states->includes(self.historyState.lastKnownActiveState) endif endif

//operationnal semantics of UML2aspect class StateMachine { operation runToCompletion(e : Event) is do // suivre la transition trouvée en activant l'état // cible et en modifiant en conséquence la hiérarchie d'états actifs end}

//operationnal semantics of UML2aspect class StateMachine { operation runToCompletion(e : Event) is do // suivre la transition trouvée en activant l'état // cible et en modifiant en conséquence la hiérarchie d'états actifs end}

16/31

Running system = exec(Model)Running system = exec(Model)

17/31

Model@run.timeModel@run.time

Overloaded term● Deals originally with software

adaptation issues at runtime

Advantage● Provides a reasoning support

on a running system

Drawback● Holding a causal link: M has to

remain the strict reflect of S

MM

SS

adaptation ?

représentation modification

Adaptationloop

18/31

Model@run.time + xModelingModel@run.time + xModeling

Treats the specific case where the considered running system is a model under execution

Idea : collapsing the adaptation loop● Solves the causal link issue...

● ...but the merge may leads to a burdened model M''

M

S = exec(M')S = exec(M')

adaptation ?

représentation modification S = exec(M'')

adaptation ?

modification

collapse

19/31

Non-supervised adaptation (self-*)Non-supervised adaptation (self-*)

Detect a situation requiring adaptation● Known versus unknown context (e.g. a new signal)

– Green runtime event is sometimes ignored (designer's choice at design-time)

– White runtime event is actually unknown at design-time

Perform adaptation actions● CRUD operators on any runtime data

Metamodel specialization unlocks adaptation● Model (sub)typing : adding new metaclasses and new constraints

– Adding new operations accordingly : for (a) detect and (b) perform

● Choosing the right level of specialization is tactful– Domain adaptations are rare but apply on any model instance of the metamodel

– Business adaptations are frequent but only apply on some models

20/31

Subtyped Cruise Control ModelSubtyped Cruise Control Model

completeness

tagged value

+

Consistency

21/31

Dynamic adaptation of the modelDynamic adaptation of the model

22/31

Adaptable xModelingAdaptable xModeling

RunToCompletion()*

-- Each state must be associated to a transition for each identified eventcontext State def: knownEvents : Set(String) = Set{...};context State inv Completeness:self.knownEvents -> forAll( e | self.existsTransitionFor(e))

-- A transition tagged with {p, v} leads to a state also tagged with with {p, v} context StateMachine inv Consistency:......

23/31

Adaptable xModelingAdaptable xModeling

RunToCompletion()*

-- Each state must be associated to a transition for each identified eventcontext State def: knownEvents : Set(String) = Set{...};context State inv Completeness:self.knownEvents -> forAll( e | self.existsTransitionFor(e))

-- A transition tagged with {p, v} leads to a state tagged with with {p, v} context StateMachine inv Consistency:......

//adaptation operational semanticsaspect class StateMachine { operation runToCompletion(e : Event) is do if not e.isKnown() then

//introduces the new state and transitions thereofend

//same as usual (nominal behavior) end}

//adaptation operational semanticsaspect class StateMachine { operation runToCompletion(e : Event) is do if not e.isKnown() then

//introduces the new state and transitions thereofend

//same as usual (nominal behavior) end}

aspect class Event { operation isKnown() : Boolean is do //checks if an event is unknown or not end}

aspect class Event { operation isKnown() : Boolean is do //checks if an event is unknown or not end}isKnown()*

24/31

From craft to engineering with MDEFrom craft to engineering with MDE

Modeling

xModeling

AdaptablexModeling

Metamodel (static)+ [exec. translational semantics]

Metamodel (static + dynamic)+ exec. operational semantics

Metamodel (static + dynamic + adaptative) + adapt. operational semantics

25/31

Adaptation extends executionAdaptation extends execution

Execution semantics● Deals with the nominal behavior (known context)

● Operation(s) only apply on the dynamic part (the static part is on read-only mode)

Adaptation semantics● Is-a-kind-of execution semantics

● Deals with extra-ordinary situation (unknown context)

● Operation(s) may apply on all parts (static, dynamic, adaptation)

The two kinds of semantics are mixed

26/31

Implementation ChoicesImplementation Choices

Classic programming● Adaptation is tangled into execution

OO programming● Adaptation overrides execution (and calls « super »)

Contract-based programming● Adaptation occurs when a precondition of execution is violated

Aspect-oriented programming● Adaptation is woven into execution

xModeling !● Adaptation is modeled with a DSL and calls back to execution

27/31

xModeling built without MDExModeling built without MDE

PauWare engine (www.pauware.com)● Execution engine (VM) for statechart models

● Implements the complete UML2 execution semantics specification

● API written in Java (hence ported effortlessly to Android)

JavaJavaPauWare APIPauWare API

Code/xml that describes the statechart model to be loaded

Engine that executes the model loaded (« run-to-completion »)

Free implementation of the actions(called by reflection from the engine)

Consumes an event for each execution step

28/31

Android + PauWareAndroid + PauWare

SERVICEBROADCAST

RECEIVER

Android OS

AN

DR

OID

C

ON

NE C

TOR

e1/foo

e1

public void foo() { //do something}

public void bar() { //do other thing}

A statechart model

runs-to-completion

starts invokes

PauWareExecution

Engine

Java

xmiscxml

29/31

Supervised adaptationSupervised adaptation

Ability to load a new model on-the-fly● A model is just a runtime data taken as input of the engine

● Actions' implementation have to stay unchanged

SERVICE

BROADCASTRECEIVER

Android OS

AN

DR

OID

C

ON

NEC

TOR

events

runs-to-completion

starts invokes

PauWareExecution

Engine

Model Server

Google Cloud

Messaging

Push Notification

Fresh data retrieval

Adapter

e1/foo

public void foo() { //do something}

public void bar() { //do other thing}

30/31

World Wide Modeling (wwm)World Wide Modeling (wwm)

MDE-specific URI● model://host[:port]/M3/M2/M1

– model://localhost/Ecore/UML2/train

– model://localhost/Ecore/OCL/

Commands● model://host/M3?list

● model://host/M3/M2?info

● model://host/M3/M2/M1#fragment

Getting started (requires )● $> npm install wwm● JavaScript API for client-side and server-side programming

31/31

Thank you for your attentionThank you for your attention

?