Describing Web Service Architectures through Design-by-Contract

Architectural description languages (ADLs) are used to specify a high-level, compositional view of a software application, specifying how a system is to be composed from coarse-grain components. ADLs usually come equipped with a formal dynamic semantics, facilitating specification and analysis of distributed and event-based systems. In this paper, we describe the TrustME, an ADL framework that provides both a process and a structural view of web service-based systems. We use Petri-net descriptions to give a dynamic view of business workflow for web service collaboration. We adapt the approach of Schmidt to define a form of Meyer's design-by-contract for configuring workflow architectures. This serves as a configuration-level means of constructing safer, more robust systems.

Trust-By-Contract: Modelling, Analysing and Predicting Behaviour in Software Architectures

Architecture description languages (ADLs) are used to specify high-level, compositional views of a software application. ADL research focuses on software composed of prefabricated parts, so-called software components. ADLs usually come equipped with rigorous state-transition style semantics, facilitating verification and analysis of specifications. Consequently, ADLs are well suited to configuring distributed and event-based systems. However, additional expressive power is required for the description of enterprise software architectures – in particular, those built upon newer middleware, such as implementations of Java’s EJB specification, or Microsoft’s COM+/.NET. The enterprise requires distributed software solutions that are scalable, business-oriented and mission-critical. We can make progress toward attaining these qualities at various stages of the software development process. In particular, progress at the architectural level can be leveraged through use of an ADL that incorporates trust and dependability analysis. Also, current industry approaches to enterprise development do not address several important architectural design issues. The TrustME ADL is designed to meet these requirements, through combining approaches to software architecture specification with rigorous design-by-contract ideas. In this paper, we focus on several aspects of TrustME that facilitate specification and analysis of middleware-based architectures for trusted enterprise computing systems.

Handling Mitigating Circumstances for Electronic Contracts

Electronic contracts are a means of representing agreed responsibilities and expected behaviour of autonomous agents acting on behalf of businesses. They can be used to regulate behaviour by providing negative consequences, penalties, where the responsibilities and expectations are not met, i.e. the contract is violated. However, long-term business relationships require some flexibility in the face of circumstances that do not conform to the assumptions of the contract, that is, mitigating circumstances. In this paper, we describe how contract parties can represent and enact policies on mitigating circumstances. As part of this, we require records of what has occurred within the system leading up to a violation: the provenance of the violation. We therefore bring together contract-based and provenance systems to solve the issue of mitigating circumstances.

Modelling and Administration of Contract-Based Systems

Mirroring the paper versions exchanged between businesses today, electronic contracts offer the possibility of dynamic, automatic creation and enforcement of restrictions and compulsions on agent behaviour that are designed to ensure business objectives are met. However, where there are many contracts within a particular application, it can be difficult to determine whether the system can reliably fulfil them all; computer-parsable electronic contracts may allow such verification to be automated. In this paper, we describe a conceptual framework and architecture specification in which normative business contracts can be electronically represented, verified, established, renewed, etc. In particular, we aim to allow systems containing multiple contracts to be checked for conflicts and violations of business objectives. We illustrate the framework and architecture with an aerospace example.

A contract-based system for aerospace aftercare

The logistics of the aerospace aftermarket raises a number of very interesting challenges from the perspective of electronic contracting. This is a highly dynamic domain, where contracts are established between airlines and engine manufacturers, as well as between engine manufacturers all the way down the supply lines, providing a particularly illustrative showcase for the technologies developed in the CONTRACT project. In this paper, we describe such a domain, as well as our modelling of it as a multiagent simulator where the CONTRACT framework has been used to monitor for compliance with norms.

Case studies for contract-based systems

Of the ways in which agent behaviour can be regulated in a multiagent system, electronic contracting – based on explicit representation of different parties' responsibilities, and the agreement of all parties to them – has significant potential for modern industrial applications. Based on this assumption, the CONTRACT project aims to develop and apply electronic contracting and contract-based monitoring and verification techniques in real world applications. This paper presents results from the initial phase of the project, which focused on requirements solicitation and analysis. Specifically, we survey four use cases from diverse industrial applications, examine how they can benefit from an agent-based electronic contracting infrastructure and outline the technical requirements that would be placed on such an infrastructure. We present the designed CONTRACT architecture and describe how it may fulfil these requirements. In addition to motivating our work on the contract-based infrastructure, the paper aims to provide a much needed community resource in terms of use case themselves and to provide a clear commercial context for the development of work on contract-based system.

Vector Theory of Spontaneous Lorentz Violation

Classical electromagnetism predicts two massless propagating modes, which are known as the two polarizations of the photon. On the other hand, if the Lorentz symmetry of classical electromagnetism is spontaneously broken, the new theory will still have two massless Nambu-Goldstone modes resembling the photon. If the Lorentz symmetry is broken by a bumblebee potential that allows for excitations out of the minimum, then massive modes arise. Furthermore, in curved spacetime, such massive modes will be created through a process other than the usual Higgs mechanism because of the dependence of the bumblebee potential on both the vector field and the metric tensor. Also, it is found that these massive modes do not propagate due to the extra constraints.

Psychological and biochemical mechanisms of schizoprenia

Schizophrenia is a disease whose physical cause is unknown despite the attempts of several research teams to discover a physical basis for it. Some success has been gained in genetic studies which indicate that schizophrenia is an inherited disability. However, since research tools are at present so sadly inadequate, the value of pursuing a genetic line of reasoning is questionable. To compensate for the lack of biochemical certainties in treating mental illness, psychological theories have been constructed to explain the schizophrenia syndrome. Normal personality is seen as the resultant of environmental and inherited influences. Involved in the formation of personality are the processes of differentiation and integration, maturation of inherited traits, and the learning processes. As personality develops. consciousness of the self, inferiority feelings, and compensatory mechanisms, and the transformation of interests into drives exert a decided influence upon personality growth. Finally, in the mature personality, an integrating philosophy of life, a large variety of interests, and the possibility of self-objectification become evident.

Contract enforcement and incentive compatibility in large economies with differential information: the role of exact feasibility

We consider exchange economies with a continuum of agents and differential information about finitely many states of nature. It was proved in Einy, Moreno and Shitovitz (2001) that if we allow for free disposal in the market clearing (feasibility) constraints then an irreducible economy has a competitive (or Walrasian expectations) equilibrium, and moreover, the set of competitive equilibrium allocations coincides with the private core. However when feasibility is defined with free disposal, competitive equilibrium allocations may not be incentive compatible and contracts may not be enforceable (see e.g. Glycopantis, Muir and Yannelis (2002)). This is the main motivation for considering equilibrium solutions with exact feasibility. We first prove that the results in Einy et al. (2001) are still valid without free-disposal. Then we define an incentive compatibility property motivated by the issue of contracts’ execution and we prove that every Pareto optimal exact feasible allocation is incentive compatible, implying that contracts of a competitive or core allocations are enforceable.

"Escala de ambiguidade"

O objetivo deste trabalho foi a construção de um instrumento para medir o nível de ambiguidade expresso pelos indivíduos em situações simples do cotidiano. Definiu-se como nível de ambiguidade, a capacidade do indivíduo para criar ambiguidade diante de determinadas situações sociais. Este trabalho vem como consequência da tese de doutorado "Anomia e Desorganização: estudo psicológico em contexto brasileiro", elaborada em 1981 e cujos resultados, confrontados com a realidade cotidiana, fizeram ressaltar o modelo ambíguo característico de nossa sociedade, que se afigura sob a forma de variadas contradições nas atitudes dos indivíduos. A ambiguidade parece ser encontrada no sistema como resultante da interpretação que o indivíduo dá a padrões, leis, normas e valores ambíguos ou ainda como consequência da própria violação ou desinformação a respeito das regras, das constantes reformulações, da desconfiança, da adaptação social de um modo geral. O enfoque teórico se baseou fundamentalmente em teorias antropológicas e sociais que propõem a realidade como algo construído pelo indivíduo e onde apareceria o comportamento ambíguo como resultante da interrelação entre o indivíduo e o meio social no qual ele se desenvolve. Para a fundamentação da escala foram isolados dois fatores a saber: (1) a ambiguidade como fator social e (2) a ambiguidade como fator psicológico.