programmed graph rewriting with devs

McGill UniversitySchool of Computer Science

1

‘07

Programmed Graph Rewriting with DEVS

Eugene Syrianiand

Hans Vangheluwe

McGill UniversitySchool of Computer Science

http://www.se.eecs.uni-kassel.de/se/index.php?642



2

‘07

OVERVIEW

In the context

Overview of the Discrete EVent system

Specification (DEVS) formalism

Building example with AToM3

Graph Rewriting Control Flow (GRCF):

Mimic AToM3 and beyond

Summary



3

‘07

IN THE CONTEXT• Model transformation: Programmed Graph

Rewriting

• At least as expressive as: GreAT, VMTS, Fujaba, ProGreS, MOFLONSequencing, Branching, Looping, Hierarchy, Parallelism

• Cleanly tear apart– Transformation entities– Control flow, structure, hierarchy

• DEVS gives us time and modularity too



4

‘07

OVERVIEW

In the context






Summary



5

‘07

OVERVIEW OF THE DEVS FORMALISM• Bernard Zeigler, late ‘70s

• Basis for compositional modelling and simulation of discrete event systems

• Design, performance analysis and implementation



6

‘07

OVERVIEW OF THE DEVS FORMALISM

• Block: Atomic / Coupled

• Port: Inport / Outport

• Event

• Global time



7

‘07


Atomic DEVS:– Time Advance– Output Function– Internal Transition– External Transition

ATOMIC



8

‘07

OVERVIEW OF THE DEVS FORMALISMCoupled DEVS

CA1

A2

A3



9

‘07

C


Coupled DEVS:– Select Function

A1

A2



10

‘07


class AExample(AtomicDEVS):

def __init__(self):

self.state = ExampleState() self.in = self.addInPort()

self.out = self.addOutPort()

def extTransition(self):

X = self.peak(self.in)

...

return self.state

def intTransition(self):

...

return self.state

def outputFnc(self):

...

self.poke(self.out, Y)

def timeAdvance(self):

return 1

Our implementation: pythonDEVSclass CExample(CoupledDEVS):

def __init__(self):

self.M1 = self.addSubModel(Example())

self.M2 = self.addSubModel(Example())

self.connectPorts(self.M1.out, self.M2.in)

def select(self, immList):

return immList[0]



11

‘07

OVERVIEW

In the context






Summary



12

‘07

BUILDING EXAMPLE WITH ATOM3 [1]

Simplified PacMan formalism [2]

[1] de Lara J., Vangheluwe H., AToM3: A tool for multi-formalism and meta-modelling, LNCS (2002), 174-188[ 2] Heckel R., Graph Transformation in a nutshell, ENTCS (2006), 187-198



13

‘07

BUILDING EXAMPLE WITH ATOM3

Build the Meta-Model of the PacMan formalism



14

‘07


Build the Graph Grammar



15

‘07



14

2

1

2

5 pacLink

3

ghostLink

3

ghostLink

1: return self.LHS.nodeWithLabel(1).score + 1

1

2

3

1

2

35

4

pacLink

foodLink

6

4

pacLink

P 1

P 2



16

‘07



4

1 2

36

gridLeft

ghostLink

1 2

3

4

7

gridLeft

ghostLink

4

1 2

5

gridRight

pacLink

1 2

4

6

gridRight

pacLink

33

P 3

P 3



17

‘07




18

‘07


• Capture a trace of execution– Keep log of used rules



19

‘07

OVERVIEW

In the context






Summary



20

‘07

GRAPH REWRITING CONTROL FLOW• DEVS blocks– Atomic block: encapsulate the graph rewriting rule

– Coupled block: encapsulate the graph grammar

• Events– Inport: recieve the host graph

– Outport(s): send the transformed graph



21

‘07

GRAPH REWRITING CONTROL FLOW



22

‘07

Trace


Model AToM3’s graph transformation engineUserInput

Control

Graph Transformation

Rules

Input graph Step

Send graph to transform

Transformed graph

Rules used



23

‘07


Graph transformation engineUserInput

g_out out_stepdone_rcv

Controllerg_init done_send in_step

g_out

g_modified

g_unmodified

Trace

g_in g_succeed

match_fail

match_succeed

g_in

match_fail

trace

trace

g_in

g_fail

trace

GGRule

GGRule

match_succeed

GGRules



24

‘07

GRAPH REWRITING CONTROL FLOWManaging priorities

g_in

GGRules

Synchronizer

match_fail

g_in

g_in

abort

match_succeed

Priority ng_in

abort

abort

out_fail

match_failGGRule GGRule

match_succeed

in_success in_fail

out_success g_succeed

g_fail

GGRule

Priority n+1

Non-determinism:Randomize select function



25

‘07

GRAPH REWRITING CONTROL FLOWUse compiled version of AToM3’s rule

class pacDie:

...



26

‘07

import compiled rules…



def __init__(self):

self.state = ExampleState() self.in = self.addInPort()

self.out = self.addOutPort()



...

return self.state

def intTransition(self):

...

return self.state

def outputFnc(self):

...

self.poke(self.out, Y)

def timeAdvance(self):

return 1



27

‘07

GRAPH REWRITING CONTROL FLOWExtension of AToM3’s graph transformation engine

g_out out_step

g_init done_send in_step

done_rcv

g_out

g_succeed

g_failg_in

AutonomousRules

Usercontrolled

Rules

g_fail

g_modifiedg_unmodified

g_in

out_control

control_out

control_in

Controller

User

in_control



28

‘07


Up Down Left Right

g_incontrol_in

key g_in

g_up

g_down

g_in

match_succeedmatch_fail

g_in


g_in


g_in

match_fail

Dispatchg_left

out_fail

in_successin_fail

out_success

g_succeedg_fail

User controlled Rules

match_succeed

g_right



29

‘07

Autonomous Rules

match_fail

g_in

match_fail

g_in


g_in g_succeed

match_succeed

g_in

g_fail

Kill

Eat

Ghost Move

match_succeed

match_fail

match_succeed



30

‘07

OVERVIEW

In the context






Summary



31

‘07

SUMMARY

SequenceBranchingLoopingHierarchy + ModularityParallelism

Control flow structure properties satisfied



32

‘07

Are we at the right level of abstraction?Is it the way industry should go in

model transformation?



33

‘07

“[...] the rule execution semantics is similar to the execution semantics of asynchronous

dataflow graphs and DEVS, but with a difference in the hierarchical rule execution.

[...] the class diagrams Figs. 14 and 15 introduce the same concepts as found in DEVS.”

A. Agrawal et al. The design of a language for model transformations. SoSym, 2006



34

‘07

CONCLUSION AND FUTURE WORK

• DEVS is a sequential, deterministic formalism

• Parallel-DEVS

• Kiltera (CSP-like languages)

Parallelism



35

‘07


• Metric, Statistics

• Timed graph transformation

• Real-Time DEVS

Time



36

‘07


• Event-driven Graph Rewriting

• Modelling of the user

User - Events



37

‘07


• Optimization hints

• Information on the flow

• Replace python code by... Statechart?

• Multi-formalism

• Add an AI block in the autonomous rules

Some Extensions



38

‘07



def __init__(self):

self.state = ExampleState()

self.in = self.addInPort()

self.out =

self.addOutPort()



...

return self.state

return 1

e(AtomicDEVS):

def ___(self):

self.state = ExampleState()


self.out = hsdhfjhb

Sdvjvkv

Ds

v

return 1

classself.state =

ExampleState()sdvv


self.out =

self.addOutPort()



...

return sdsdfsdfsdfsfsdfsdf

In AToM3 Outside AToM3


programmed graph rewriting with devs

Documents