GuideTutorialMarkedGraph

GEMOC xDSML definition tutorial with MarkedGraph

This tutorial aims at demonstrating the power of the GEMOC studio to define an executable semantics and provide graphical animation for a DSML. It relies of the marked graph language.

Starting defining an xDSML

Marked Graph is a Petri net in which every place has exactly one incoming arc and exactly one outgoing arc. As a consequence, it a concurrent language (several transitions may be fired) and has no conflict.

In this section, we first initialize the xDSML project for MarkedGraph with the provided Abstract Syntax (AS) and Concrete Syntax (CS). The next subsections explains MarkedGraph and can be skipped by the reader who already know that language.

Initializing the MarkedGraph xDSML project with the provided AS and CS

First, start by creating a new xDSML project (New > Project > GEMOC Project / new xDSML Project), with your desired name (for instance "org.gemoc.example.markedgraph"). A file project.xml is created. When opened, it provides the xDSML view which summarizes all the important resources used in an xDSML project (which are part of and managed by other projects). This view is a kind of dashboard or control center to have quick access to any important resource of the project.

TODO : Show the xDSML view?

TODO : Click on the genmodel and select //generate all//

TODO : Explain how to initialize the EMF, EMFmodel, Graphical Visualization, etc.

Abstract Syntax

Figure 1. Abstract Syntax of MarkedGraph

Example of Marked Graph model (and Concrete Syntax)

The one of Wikipedia?

Execution Semantics Definition

TODO: Describe the execution semantics.

A transition can be fired if there is at least one token in every of each entry place. When fired, one token is removed from each entry place and one token is added to each output place.

Only one transition is fired at a time.

One want to know the number of token in any place during the execution. For example, it can be shown as a number inside the circle representing a place and the size of the circle can be XXX proportionel at the number of it contains.

% XXX: Fireable transitions may be drawn in green.

Defining the Execution Semantics of Marked Graph with the GEMOC Studio

DSA

First we define the DSA (Domain Specific Actions). It includes Execution Data (ED) and Execution Functions (EF) which describe evolution of the ED.

Creating the DSA

Click on K3 project in the xDSML view (Behavioral definition / DSA definition). The wizard to create of new Kermeta 3 project is launched with the name of the project initialized (k3dsa is the last name).

Clicking again on K3 project will now allow to choose and open markedgraph.xtend. It has been initialized with a template that can be discarded.

Code of the DSA

Fill in the following code in the markedgraph.xtend resource:

link:MarkedGraph/markedgraph.xtend[role=include]

Explanation of the DSA

When executing a Marked Graph model, we want to know the number of token of a place. This is an Execution Data as it is changed during the execution of the model.

We want to add a new attribute called tokenCount on the Place metaclass.

ED

Current marking

EF

Fire on a transition moves token form input place to output places.

MoCC

Right click on the ECL project in the DSE definition part. Select the Ecore file markedgraph.ecore and the root container model element: markedgraph::MarkedGraph. The file markedgraph.ecl is created in the org.gemoc.example.markedgraph.dse.

link:MarkedGraph/markedgraph.ecl[role=include]

What should be explained?

• The main principles (we can fire as much transition has the initial token count of a place, thus a delayed is introduce)

• We want to ensure that one init is done before any fire (and only once)

Provide a pointer to another tutorial (or a new part of this one) which explains how to capitalize pieces of MoCC in a library.

Provide a pointer to a MoCCML version which uses constraint automata to define the MoCC.

DSE

TODO: In the first place or at the end?

Firing a transition

Visual Animation

Questions/Remarks…​

Questions on the MoCC from summerSchool :

• why delayedBy p.initialMarking and not delayedBy 1? =⇒ Because we can make as much read as there is initialMarking token in the place. Any write in that place, means that a new read can be done.

• is it still right if the initial marking is P2 = 1 (all other places is 0) ? =⇒ No. But in any case, this initialMarking will result in a deadlock.

• what if there is several places which are initially marked? =⇒ See read/write semantics

• typo in the DelayFor expression on slide 93: two times outputTransition.fireCall

Questions on the implementation :

• A transition has no more that one input or output place. Should be any number !

Questions:

• use execute for the EF on transition instead of fire and use fire (or trigger) for the DSE instead of fireCall.

Questions de forme :

• Utilisation des abbréviations (MoCC, DSA, EF, ED, AS, CS, etc.) : Prévoir un lexique sur le site ?

• Éviter d’avoir trop de sections : par exemple, supprimer ED, EF.