http://chess.eecs.berkeley.edu/

February 12, 2009 Center for Hybrid and Embedded Software Systems

Encapsulated Model Transformation Rule

A transformation rule contains 3 components:

1. Pattern: match a subgraph in a given model

1) A graph containing interconnected actors and relations.

2) Matchers (e.g., C1 and C2 in SimplifyMultiply) can be used to match arbitraryactors satisfying certain criteria

3) Textual constraints are evaluated once a subgraph is found and for the match tobe successful, all constraints must be true.

2. Replacement: replace the matched subgraph with a new graph

3. Correspondence: relate objects in pattern to replacement

Model Transformation with the Ptera Controller

Thomas H. Feng

Edward A. Lee

Ptera (Ptolemy Event Relationship Actor)

A discrete-event model of computation for event-oriented designs (compared to actor-oriented, object-oriented, state-oriented, etc), originally introduced by Schruben in 1983.

Semantics

1. Initialize event queue to contain only the initial events (green ones)

2. Repeat until event queue is empty

1) Remove the first event from event queue

2) Execute its action

3) For each outgoing edge whose guard is true

• Schedule the event that the edge points to

4) If the event is a final event (red one)

• Clear event queue

Hierarchical Composition

1. An event can be associated with a refinement. Therefinement is fired when:

1) the event is processed, or

2) input is received at any input port, or

3) the refinement itself requests (with fireAt)

2. Ptera as refinement of DE

Event Library (Compared to Actor Library)

Analysis

Analyze the model and annotate it with properties (Jackie Leung and Thomas Mandl)

Execution Control

Execute the model

Wait for a specified amount of real time

Stop the transformation workflow

Test the guards on the outgoing edges

IO

Clone the model

List all files in the directory with filters

Read the model stored in a file

Output the model to a file

User Interaction

Pop up a dialog to ask the user for parameters

Wait for user input but allow time to advance t

Report a message in a window or a dialog

Set window properties (on top, size, enabled, etc)

Transformation

Perform pattern matching and report result

Perform pattern matching and transformation

View the model in a separate window

Generic

Fire an action specified in the Ptolemy action language, and fire the submodel if there is one associated with it as a refinement

Example Applications

Ptera

Simulate sequential discrete-event processes

Compose with concurrent models of computation (DE,dataflow, etc) to specify parallel processes

Describe dependency relationship between tasks inworkflows

Model Transformation

Statically optimize models based on analysis result

Construct new models (by transforming an empty model)

Dynamically configure system structures according to therun-time states

Simulate structural evolution of systems

SimplifyMultiply

SimplifyDivide

RemoveMultiply

And Much More…

Events have an easy-to-extend API similar to actors. Override the fire method to perform customized action:

public RefiringData fire(ArrayToken arguments) throws IllegalActionException;