Showing papers on "Process architecture published in 1980"

Performance Evaluation of Asynchronous Concurrent Systems Using Petri Nets

Abstract: Some analysis techniques for real-time asynchronous concurrent systems are presented. In order to model clearly the synchronization involved in these systems, an extended timed Petri net model is used. The system to be studied is first modeled by a Petri net. Based on the Petri net model, a system is classified into either: 1) a consistent system; or 2) an inconsistent system. Most real-world systems fall into the first class which is further subclassified into i) decision-free systems; ii) safe persistent systems; and iii) general systems. Procedures for predicting and verifying the system performance of all three types are presented. It is found that the computational complexity involved increases in the same order as they are listed above.

Timed Petri nets and preliminary performance evaluation

Abstract: It is shown that the behavior of a certain class of timed Petri nets can be represented by a finite labeled directed graph in which the labels describe times and probabilities of transitions between vertices of the graph. Further analysis of such a graph can be done by techniques known for Markov chains. The method is applied to evaluation of some performance indices for two simple processor architectures. The timed Petri nets modeling the processors are shown and the resulting performance indices are compared. Some other architectures are discussed shortly.

Protocol Representation with Finite-State Models

Abstract: A three-layer model of a computer network is used to introduce the concept of interface and of end-to-end protocols. Using a simple interface protocol as example, finite state automaton and Petri nets are introduced. The idea of an interface machine is rejected and the problems related to the transmission medium are approached. End-to end protocols request a global model which includes two local models and a transmission medium model. However, the local model has to be generalized. This eventually leads to the association of the state of the automaton with a context. Petri nets have also to be expanded. Models presented here have been successfully used for modeling transport protocols.

Optimization of assembly code generation using Petri nets

Abstract: This paper gives a Petri net approach to the determination of an optimal assembly language code and it appears to be useful for code optimization in the process of compilation. The proposed technique is novel in the sense that only vector addition on a matrix is needed. It is simple and requires little computation.

An Algebraic Structure of Petri Nets

Abstract: The paper concerns algebraic properties of Petrinets. A wide class of nets, called simple nets, is introduced and a lattice of these nets is defined. It turns out that nets representing sequential systems and processes are atoms of this lattice, and this fact provides the natural way of building nets representing. concurrent systems as the superposition of nets representing sequential system components.

Modified Petri nets as flowcharts for recursive programs

Abstract: The problem of graphic representation of recursive program structures is discussed. On the basis of the stack mechanism, modified Petri nets are introduced which only slightly differ from the common state machine flowcharts, but have much more representation power.

Petri Nets and Reliable Real Time Systems

Abstract: The zero-test problem is a well-known limitation of Petri nets, and unfortunately it appears very frequently when reliable real-time systems are concerned. If the Petri net is bounded (it is generally the case when actual systems are specified), the zero-test problem can be solved by the introduction of complementary places. Nevertheless this solution presents three major drawbacks: the specification becomes little readable, the net can rarely be reduced, the information given by the linear invariants does not take into account the elementary loops and therefore the zero-tests.

Petri Nets and Semantics of System Descriptions

Abstract: The full version of this paper has been published as: DAIMI PB-116, Computer Science Department, Aarhus University. It can be requested from the address above.