Ptolemy: A Framework for Simulating and Prototyping Heterogeneous Systems

Abstract

Ptolemy is an environment for simulation and prototyping of heterogeneous systems. It uses modern object-oriented software technology (C++) to model each subsystem in a natural and efficient manner, and to integrate these subsystems into a whole. Ptolemy encompasses practically all aspects of designing signal processing and communications systems, ranging from algorithms and communication strategies, simulation, hardware and software design, parallel computing, and generating real-time prototypes. To accommodate this breadth, Ptolemy must support a plethora of widely-differing design styles. The core of Ptolemy is a set of object-oriented class definitions that makes few assumptions about the system to be modeled; rather, standard interfaces are provided for generic objects and more specialized, application-specific objects are derived from these. A basic abstraction in Ptolemy is the Domain, which realizes a computational model appropriate for a particular type of subsystem. Current examples of domains include synchronous and dynamic dataflow, discrete-event, and others appropriate for control software and embedded microcontrollers. Domains can be mixed as appropriate to realize an overall system simulation. Some current applications of Ptolemy include networking and transport, call-processing and signaling software, embedded microcontrollers, signal processing (including implementation in realtime real-time), scheduling of parallel digital signal processors, board-level hardware timing simulation, and combinations of these.Key words: Heterogeneity, mixed-mode, simulation, prototyping, object-oriented programming INTRODUCTIONPtolemy is a simulation and rapid prototyping framework for heterogeneous systems. It is ideal for applications in which heterogeneity is a key characteristic. such as:• Design of multimedia networks;• Real-time embedded software;• Hardware/Software codesign;• Control and call-processing in telecommunications networks;• Rapid prototyping of new telecommunications services;• Mixed-mode hardware simulation;• Mapping applications onto heterogeneous multiprocessor systems; and• Mixed signal processing and real-time control.For example, in the design of multimedia networks, we are interested in studying the interaction between transport, compression or compositing signal processing, and control software in voice or video services over cell-relay networks. In telecommunication systems we are interested in studying the interaction between call-processing software and hardware switch elements. To develop new telecommunication services, we must jointly design control software, signal processing, transport, and hardware elements.In hardware design we are interested in modeling components with varying detail, such as behavioral, logic, timing, and circuit. In system-level design, we may wish to jointly design the communications infrastructure and the processing elements. We may also wish to synthesize (in combination) microcode for specialized processors, C code for generic processors, routi...

Disciplined Heterogeneous Modeling

“…In this paper, we focus on techniques that combine actors with multi-paradigm modeling. An early systematic approach to such mixed models was realized in Ptolemy Classic [4]. Ptolemy II is a successor to Ptolemy Classic [5].…”

“…The technique I describe is that developed in the Ptolemy Project, and largely previously presented in [4,5,6]. The key idea is to use a common abstract syntax for a diverse set of actor-oriented models, and to hierarchically compose those models using an abstract semantics.…”

Off-Line Performance Prediction of Message-Passing Applications on Cluster Systems

“…However, a wide number of papers deals with parallel and distributed system modeling and performance analysis [17][18], and it is likely that many existing simulation environments and tools could be applied to carry out performance analyses similar to those that are the object of this paper. Other authors focus their interest in tools for performance-driven software development, mainly in the context of Performance Engineering (see per example [19][20]).…”

Analyzing concurrency in streaming applications

“…The system components in the collection of components that form a system can be described in different models of computation. The Ptolemy framework [BHLM94] formalizes the interaction of different models of computation. As a result, a system composed out of system components in different models of computation can be analyzed.…”