Distributed execution of bigraphical reactive systems

The bigraph embedding problem is crucial for many results and tools about bigraphs and bigraphical reactive systems (BRS). Current algorithms for computing bigraphical embeddings are centralized, i.e. designed to run locally with a complete view of the guest and host bigraphs. In order to deal with large bigraphs, and to parallelize reactions, we present a decentralized algorithm, which distributes both state and computation over several concurrent processes. This allows for distributed, parallel simulations where non-interfering reactions can be carried out concurrently; nevertheless, even in the worst case the complexity of this distributed algorithm is no worse than that of a centralized algorithm

Modelling IEEE 802.11 CSMA/CA RTS/CTS with stochastic bigraphs with sharing

Stochastic bigraphical reactive systems (SBRS) is a recent formalism for modelling systems that evolve in time and space. However, the underlying spatial model is based on sets of trees and thus cannot represent spatial locations that are shared among several entities in a simple or intuitive way. We adopt an extension of the formalism, SBRS with sharing, in which the topology is modelled by a directed acyclic graph structure. We give an overview of SBRS with sharing, we extend it with rule priorities, and then use it to develop a model of the 802.11 CSMA/CA RTS/CTS protocol with exponential backoff, for an arbitrary network topology with possibly overlapping signals. The model uses sharing to model overlapping connectedness areas, instantaneous prioritised rules for deterministic computations, and stochastic rules with exponential reaction rates to model constant and uniformly distributed timeouts and constant transmission times. Equivalence classes of model states modulo instantaneous reactions yield states in a CTMC that can be analysed using the model checker PRISM. We illustrate the model on a simple example wireless network with three overlapping signals and we present some example quantitative properties

Towards a bigraphical encoding of actors

Actors are self-contained, concurrently interacting entities of a computing system. They can perform local computations, communicate via asynchronous message passing with other actors and can be dynamically created. Bigraphs are a fully graphical process algebraic formalism, capable of representing both the position in space of agents and their inter-connections. Their behaviour is specified by a set of reaction rules. In this paper, we present a bigraphical encoding of a simplified actor language with static topology. We express actor configurations in terms of sorted bigraphs while the rules of the actor operational semantics are encoded by bigraphical reactive rules

Towards distributed bigraphical reactive systems

3noThe bigraph embedding problem is crucial for many results and tools about bigraphs and bigraphical reactive systems (BRS). There are algorithms for computing bigraphical embedding but these are designed to be run locally and assume a complete view of the guest and host bigraphs, putting large bigraphs and BRS out of their reach. To overcome these limitations we present a decentralized algorithm for computing bigraph embeddings that allows us to distribute both state and computation over several concurrent processes. Among various applications, this algorithm offers the basis for distributed BRS simulations where non-interfering reactions are carried out concurrently.openopenMansutti, Alessio; Peressotti, Marco; Miculan, MarinoMansutti, Alessio; Peressotti, Marco; Miculan, Marin

Computing (optimal) embeddings of directed bigraphs

Bigraphs and bigraphical reactive systems are a well-known meta-model successfully used for formalizing a wide range of models and situations, such as process calculi, service oriented architectures, multi-agent systems, biological systems, etc. A key problem in the theory and the implementations of bigraphs is how to compute embeddings, i.e., structure-preserving mappings of a given bigraph (the pattern or guest) inside another (the target or host). In this paper, we present an algorithm for computing embeddings for directed bigraphs, an extension of Milner's bigraphs which take into account the request directions between controls and names. This algorithm solves the embedding problem by means of a reduction to a constraint satisfaction problem. We first prove soundness and completeness of this algorithm; then we present an implementation in jLibBig, a general Java library for manipulating bigraphical reactive systems. The effectiveness of this implementation is shown by several experimental results. Finally, we show that this algorithm can be readily adapted to find the optimal embeddings in a weighted variant of the embedding problem

Towards a bigraphical encoding of actors

Actors are self-contained, concurrently interacting entities of a computing system. They can perform local computations, communicate via asynchronous message passing with other actors and can be dynamically created. Bigraphs are a fully graphical process algebraic formalism, capable of representing both the position in space of agents and their inter-connections. Their behaviour is specified by a set of reaction rules. In this paper, we present a bigraphical encoding of a simplified actor language with static topology. We express actor configurations in terms of sorted bigraphs while the rules of the actor operational semantics are encoded by bigraphical reactive rules

Bigraph Metaprogramming for Distributed Computation

Ubiquitous computing is a paradigm that emphasises integration of computing activities into the fabric of everyday life. With the increasing availability of small, cheap computing devices, the ubiquitous computing model seems more and more likely to supplant desktop computing as the dominant paradigm. Similarly, the presence of high-speed network connectivity between vast numbers of computers has already made distributed computing the preferred paradigm for many application domains. Unfortunately, traditional approaches to software development are not necessarily well-suited to developing software in a post-desktop world. We present an extension to the bigraphical reactive systems formalism that enables us to construct a programming language based upon it. We believe that this programming language provides programmers with an environment better suited to the challenges that arise when creating software within a distributed or ubiquitous computing paradigm. We detail our modification to the theory of bigraphical reactive systems that enables metaprogramming. Finally, we provide a description of our prototype implementation of a programming language that enables metaprogramming of bigraphical reactive systems

A Bigraphical Vending Machine as a Webservice: From Specification and Analysis to Implementation using the Bigraph Toolkit Suite

A bigraph-driven vending machine is implemented. The application is realized as a Spring-based webservice. Actions can be initiated by REST endpoints. The system follows a rule-based architecture, where possible operations are grounded on a rule set. Bigraphical Reactive Systems are used for the specification and execution. The actual state of the application is a bigraph stored in a database, which can be viewed and altered directly in the database. A history of states is kept - the application can be transferred to any prior state. The application can be updated or extended by merely changing the bigraphical database model.:First Part: A system of a vending machine is specified and analyzed using BDSL. This concerns the static and dynamic aspects of the system. Second Part: The analysis results are re-used for the implementation using Bigraph Framework. The application is realized as a webservice that is built using the Spring framework.Ein bigraph-gesteuerter Verkaufsautomat wird implementiert. Die Anwendung ist als Spring-basierter Webservice realisiert. Aktionen können über REST-Endpunkte initiiert werden. Das System folgt einer regelbasierten Architektur, bei der die möglichen Operationen auf einem Regelsatz beruhen. Für die Spezifikation und Ausführung werden Bigraphical Reactive Systems verwendet. Der aktuelle Zustand der Anwendung ist ein in einer Datenbank gespeicherter Bigraph, der direkt in der Datenbank eingesehen und verändert werden kann. Es wird eine Historie der Zustände geführt - die Anwendung kann in einen beliebigen früheren Zustand überführt werden. Die Anwendung kann aktualisiert oder erweitert werden, indem lediglich das bigraphische Datenbankmodell geändert wird.:First Part: A system of a vending machine is specified and analyzed using BDSL. This concerns the static and dynamic aspects of the system. Second Part: The analysis results are re-used for the implementation using Bigraph Framework. The application is realized as a webservice that is built using the Spring framework