Secure multi-party contracts for web-services

We consider two complementary formal approaches for describing services and their interactive behaviour. The first approach is based on the notion of contracts. Contracts are CCS-like processes that contain a description of the external observable behavior of a service. A notion of compliace has been introduced allowing to check whether the interaction between two parties terminate or gets stuck. The second proposal is based on λ-req, a core calculus for services, with primitives for expressing security policies and for composing services in a call-by-contract fashion. In the dissertation we express CCS contracts via λ-req expressions and we prove that the proposed transformation preserves compliance of contracts, by exploiting the security mechanism of λ-req. The transformation enjoys further properties. Multi-party and secure contracts are naturally handled. Moreover, the resulting notion of compliance is compositional: one can substitute a service with an equivalent one without breaking the security of the composition

Web Services Support for Dynamic Business Process Outsourcing

Outsourcing of business processes is crucial for organizations to be effective, efficient and flexible. To meet fast-changing market conditions, dynamic outsourcing is required, in which business relationships are established and enacted on-the-fly in an adaptive, fine-grained way unrestricted by geographic distance. This requires automated means for both the establishment of outsourcing relationships and for the enactment of services performed in these relationships over electronic channels. Due to wide industry support and the underlying model of loose coupling of services, Web services increasingly become the mechanism of choice to connect organizations across organizational boundaries. This paper analyzes to which extent Web services support the dynamic process outsourcing paradigm. We discuss contract -based dynamic business process outsourcing to define requirements and then introduce the Web services framework. Based on this, we investigate the match between the two. We observe that the Web services framework requires further support for cross - organizational business processes and mechanisms for contracting, QoS management and process-based transaction support and suggest ways to fill those gaps

Primitives for Contract-based Synchronization

We investigate how contracts can be used to regulate the interaction between processes. To do that, we study a variant of the concurrent constraints calculus presented in [1], featuring primitives for multi-party synchronization via contracts. We proceed in two directions. First, we exploit our primitives to model some contract-based interactions. Then, we discuss how several models for concurrency can be expressed through our primitives. In particular, we encode the pi-calculus and graph rewriting.Comment: In Proceedings ICE 2010, arXiv:1010.530

Lending Petri nets and contracts

Choreography-based approaches to service composition typically assume that, after a set of services has been found which correctly play the roles prescribed by the choreography, each service respects his role. Honest services are not protected against adversaries. We propose a model for contracts based on a extension of Petri nets, which allows services to protect themselves while still realizing the choreography. We relate this model with Propositional Contract Logic, by showing a translation of formulae into our Petri nets which preserves the logical notion of agreement, and allows for compositional verification

Redefining Stewardship: Public Lands and Rural Communities in the Pacific Northwest

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Automated Negotiation for Provisioning Virtual Private Networks Using FIPA-Compliant Agents

This paper describes the design and implementation of negotiating agents for the task of provisioning virtual private networks. The agents and their interactions comply with the FIPA specification and they are implemented using the FIPA-OS agent framework. Particular attention is focused on the design and implementation of the negotiation algorithms