In this presentation we will report on a number of projects where we have successfully applied the ASM methodology to provide abstract models for a number of problems that are commonly found in Service Oriented Architectures (SOAs). In particular, we will provide solutions for the following topics: (1) service behaviour mediation, (2) service discovery, and (3) service composition. Introduction. Service Oriented Architecture (SOA) serve as an architectural blueprint for designing flexible information systems. SOAs are built from au- tonomous functional entities, services, which inter-operate through well-defined, message-based interfaces that abstract from both programming languages and implementation platforms. The most prominent incarnation of this architectural blueprint is based on the technical specification set defined by the World Wide Web Consortium (W3C) where services expose their functionality as so-called Web1 services. The corre- sponding W3C technical report on the Web Services Architecture (7) describes a basic engagement model that identifies, among others, the following three fundamental entities: the service requester invoking functionality from a service provider through message exchanges. The definition of these message exchanges has been published and thus can be retrieved through a public service discovery service.
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"Though they provide a definition for job scheduling, they do not detail brokering steps and mechanisms at different levels. Altenhofen et al. investigated Service Oriented Architectures in , more specifically service discovery, mediation and composition. These components have some similar functionalities but this work is more focused on a unified, higher level service framework, and do not explore resource manager components. "
[Show abstract][Hide abstract] ABSTRACT: Coordination in distributed environments, like Grids, involves selecting the most appropriate services, resources or compositions to carry out the planned activities. Such functionalities appear at various levels of the infrastructure and in various means forming a blurry domain, where it is hard to see how the participating components are related and what their relevant properties are. In this paper we focus on a subset of these problems: resource brokering in Grid middleware. This paper aims at establishing a semantical model for brokering and related activities by defining brokering agents at three levels of the Grid middleware for resource, host and broker selection. The main contribution of this paper is the definition and decomposition of different brokering components in Grids by providing a formal model using Abstract State Machines.
Proceedings 8th International Workshop on Parallel and Distributed Methods in verifiCation; 12/2009
[Show abstract][Hide abstract] ABSTRACT: Formal design methods, that might serve as a basis for specifying and analyzing abstract models of service orchestrations, are needed to complement the wide range of domain-specific languages (mainly based on graphical notations) that are currently being defined for engineering service-oriented systems. This paper presents a formal and executable semantic framework for UML4SOA models of service-oriented systems. The UML4SOA language is a UML profile developed in the EU SENSORIA project for modeling services behavior focusing on service orchestration aspects. We complement the graphical model of a service orchestration scenario with a formal description that is suitable for rigorous execution-platform-independent analysis. We map the behavioral primitives of UML4SOA activity diagrams into a particular class of Abstract State Machines (ASMs) able to model notions of service interactions and orchestrations.
[Show abstract][Hide abstract] ABSTRACT: We survey the use of the Abstract State Machines (ASM) method for a rigor- ous foundation of modeling and validating web services, workflows, interaction patterns and business processes. We show in particular that one can tailor business process definitions in application-domain yet rigorous terms in such a way that the resulting ASM models can be used as basis for binding contracts between domain experts and IT technologists. The method combines the expressive power and accuracy of rule-based modeling with the intuition pro- vided by visual graph-based descriptions. We illustrate this by an ASM-based semantical framework for the OMG standard for BPMN (Business Process Modeling Notation). The framework supports true concurrency, heterogeneous state and modularity (compositional design and verification techniques). As validation example we report some experiments, car- ried out with a special-purpose ASM simulator, to evaluate various definitions proposed in the literature for the critical OR-join construct of BPMN.1
Abstract State Machines, B and Z, First International Conference, ABZ 2008, London, UK, September 16-18, 2008. Proceedings; 01/2008