DEVSView: A DEVS Visualization Tool

Wilson Venhola

Outline

Background Motivation Design Implementation Current State Future Work

Background

The Discrete EVent Systems (DEVS) specification provides a framework for the construction of discrete event hierarchical models in a modular manner.

Cell-DEVS extends the DEVS formalism, allowing the simulation of discrete event cell spaces.

Basic Models ( atomic ) are created as black boxes, and several DEVS models can be integrated together, forming a hierarchical structural model ( coupled ). In Cell-DEVS, the cells are atomic models and the cell space is created by connecting the cells together to form a coupled model.

Models communicate with each other by sending values over ports when required. These events are recorded by the simulation and indicate how the DEVS simulation is progressing and are key to visualizing the system.

Motivation

Graphical tools are crucial to understanding the behaviour of complex systems. They facilitate thinking, problem solving, and decision making. It would be useful to visualize DEVS and Cell-DEVS simulations in a 3d environment for these reasons.

The CD++ toolkit enables simulating DEVS and Cell-DEVS models, and storing the results in a text log file. The visualization tool (DEVSView) will provide a method of translating the log file into an effective visualization for a DEVS or Cell-DEVS simulation model.

Design

The tool is designed to connect to simulation results through a CD++ link.

The user can either view the simulation, connect to a simulation log file, or edit how the DEVS models are visualized.

Design

The tool design is separated into four packages:– The ViewerDisplay package handles interactions with the user to edit the properties

of the visualization and to observe the 3d animations produced.– The ViewerControl package handles complicated interactions with the

SimulationDatabase package, and ensures the integrity of the database during these interactions.

– The SimulationLink package handles connecting to results produced from a simulation.

– The SimulationDatabase package handles storage of the data associated with the visualization.

Implementation

The tool is implemented in C++, and uses OpenGL to render the output using hardware accelerated graphics.

The user interface is built on top of the cross-platform OpenGL Utility Toolkit ( GLUT ).

Visualization is accomplished by rendering text and/or images associated with the state of the simulation models ( atomic or coupled ).

The state of the visualization is updated by the events received from the simulation results.

How the visualization is updated depends on the transition rules specified in the tool.

Current State

Simple Camera movement completed Loading/Saving visualizations Visual state and Transition rule functionality

complete CD++ log file loading complete Time manipulation functionality implemented

Future Work

Visualization play, pause, speed manipulation Other visualization techniques:

– Event animations– Model movement

3d model loading ( Maya, 3d Studio max ) Environment detail objects ( Terrain, Roads,

Buildings, … ) Improved user interface (positioning/aligning models)

Summary

DEVS requires a visualization tool to facilitate thinking, problem solving and decision making.

The tool presented aims to provide a quick and simple method of visualizing simulations in 3-dimensions.

It updates a visual representation of the simulation using rules that interpret the events produced by the simulation.

The tool is partially implemented, but requires more work to enable the creation of effective visualizations.

Questions?