Process architecture

About: Process architecture is a research topic. Over the lifetime, 4876 publications have been published within this topic receiving 104171 citations.

Structuring and composability issues in Petri nets modeling

Abstract: Along Petri nets' history, numerous approaches have been proposed that try to manage model size through the introduction of structuring mechanisms allowing hierarchical representations and model composability. This paper proposes a classification system for Petri nets' structuring mechanisms and discusses each one of them. These include node fusion, node vectors, high-level nets, and object-oriented inspired Petri nets extensions, among others. One running example is used emphasizing the application of the presented mechanisms to specific areas, namely to automation systems modeling, and software engineering, where object-oriented modeling plays a major role.

On the Relationship of CCS and Petri Nets

Abstract: We give a partial order semantics to (pure) CCS via a translation into Petri nets and prove, that the interleaved behaviour of the resulting nets is equivalent to Milner's semantics. We show that a large class of CCS programs can be represented by finite nets and that this is impossible for the whole CCS.

A general way to put time in Petri nets

Abstract: Petri nets have been widely used in the past to model vari&s types of concurrent systems, including real-time systems. To do so, a variety of ad-hoc solutions have been proposed in order to allow time to be taken into account in specifications. In this paper, we initially survey these proposals and then we illustrate a new proposal (TEI nets), that unifies and generalizes all pre,vious ones. Next, we discuss how these and possibly other enrichments of the original model can be formally defined. This will be do,ne in terms of a high-level net model, called ER nets. The ability of ER nets to express a variety of behaviors justifies our choice to use them as a kernel formalism of a specification support environment that we are currently developing. In this environment, it will be possible to define new graphical notations for formal specifications and give them formal semantics in terms of the underlying ER model. This allows the specifier to tune the notation used in formal specifications to the particular expressive needs arising while modelling an application and yet base the notation on firm and rigorous grounds.

Compositional semantics for UML 2.0 sequence diagrams using petri nets

Abstract: With the introduction of UML 2.0, many improvements to diagrams have been incorporated into the language. Some of the major changes were applied to sequence diagrams, which were enhanced with most of the concepts from ITU-T's Message Sequence Charts, and more. In this paper, we introduce a formal semantics for most concepts of sequence diagrams by means of Petri nets as a formal model. Thus, we are able to express the partially ordered and concurrent behaviour of the diagrams natively within the model. Moreover, the use of coloured high-level Petri nets allows a comprehensive and efficient structure for data types and control elements. The proposed semantics is defined compositionally, based on basic Petri net composition operations.

Sealing OS processes to improve dependability and safety

Abstract: In most modern operating systems, a process is a hardware-protected abstraction for isolating code and data. This protection, however, is selective. Many common mechanisms---dynamic code loading, run-time code generation, shared memory, and intrusive system APIs---make the barrier between processes very permeable. This paper argues that this traditional open process architecture exacerbates the dependability and security weaknesses of modern systems.As a remedy, this paper proposes a sealed process architecture, which prohibits dynamic code loading, self-modifying code, shared memory, and limits the scope of the process API. This paper describes the implementation of the sealed process architecture in the Singularity operating system, discusses its merits and drawbacks, and evaluates its effectiveness. Some benefits of this sealed process architecture are: improved program analysis by tools, stronger security and safety guarantees, elimination of redundant overlaps between the OS and language runtimes, and improved software engineering.Conventional wisdom says open processes are required for performance; our experience suggests otherwise. We present the first macrobenchmarks for a sealed-process operating system and applications. The benchmarks show that an experimental sealed-process system can achieve performance competitive with highly-tuned, commercial, open-process systems.