An object based algebra for specifying a fault tolerant software architecture

AbstractIn this paper we present an algebra of actors extended with mechanisms to model crash failures and their detection. We show how this extended algebra of actors can be successfully used to specify distributed software architectures. The main components of a software architecture can be specified following an object-oriented style and then they can be composed using asynchronous message passing or more complex interaction patterns. This formal specification can be used to show that several requirements of a software system are satisfied at the architectural level despite failures. We illustrate this process by means of a case study: the specification of a software architecture for intelligent agents which supports a fault tolerant anonymous interaction protocol

Ontology driven multi-agent systems : an architecture for sensor web applications.

Thesis (Ph.D.)-University of KwaZulu-Natal, 2009.Advances in sensor technology and space science have resulted in the availability of vast quantities of high quality earth observation data. This data can be used for monitoring the earth and to enhance our understanding of natural processes. Sensor Web researchers are working on constructing a worldwide computing infrastructure that enables dynamic sharing and analysis of complex heterogeneous earth observation data sets. Key challenges that are currently being investigated include data integration; service discovery, reuse and composition; semantic interoperability; and system dynamism. Two emerging technologies that have shown promise in dealing with these challenges are ontologies and software agents. This research investigates how these technologies can be integrated into an Ontology Driven Multi-Agent System (ODMAS) for the Sensor Web. The research proposes an ODMAS framework and an implemented middleware platform, i.e. the Sensor Web Agent Platform (SWAP). SWAP deals with ontology construction, ontology use, and agent based design, implementation and deployment. It provides a semantic infrastructure, an abstract architecture, an internal agent architecture and a Multi-Agent System (MAS) middleware platform. Distinguishing features include: the incorporation of Bayesian Networks to represent and reason about uncertain knowledge; ontologies to describe system entities such as agent services, interaction protocols and agent workflows; and a flexible adapter based MAS platform that facilitates agent development, execution and deployment. SWAP aims to guide and ease the design, development and deployment of dynamic alerting and monitoring applications. The efficacy of SWAP is demonstrated by two satellite image processing applications, viz. wildfire detection and monitoring informal settlement. This approach can provide significant benefits to a wide range of Sensor Web users. These include: developers for deploying agents and agent based applications; end users for accessing, managing and visualising information provided by real time monitoring applications, and scientists who can use the Sensor Web as a scientific computing platform to facilitate knowledge sharing and discovery. An Ontology Driven Multi-Agent Sensor Web has the potential to forever change the way in which geospatial data and knowledge is accessed and used. This research describes this far reaching vision, identifies key challenges and provides a first step towards the vision

Concurrency and knowledge-level communication in agent languages

In this paper we try to answer the following questions: Is it possible to program solely at the level of an agent communication language? And if this is the case, what requirements and conditions need to be taken into account? We argue that, although a number of languages defining abstract communication primitives have been proposed in the past few years, knowledge-level programming can only be supported if a number of careful assumptions about the communication primitives and the underlying architecture are made, including asynchronous communication mechanisms, reliable message passing, and nonblocking primitives. To achieve a more rigorous understanding of these issues we proceed in a formal way. First, we postulate a set of requirements that an agent communication language should satisfy to be regarded as knowledge level. Then, we define a weak agent communication language, and we show that a synchronous version of the language does not satisfy requirements for knowledge-level programming. Finally, we show how an alternative asynchronous version of the language can be defined, which avoids the aforementioned problems. To prove these results, we introduce a general framework for reasoning on communication and concurrency aspects in the context of agent communication languages. © 1998 Elsevier Science B.V. All rights reserved