Disaster planning using automated composition of semantic OGC web services: A case study in sheltering

Geospatial web services are widely utilised to disseminate spatial data and processing capability over the internet. Combining geospatial web services and generating composite web services out of atomic services can provide users with a higher level of functionality. This paper presents a solution for the automatic composition of geospatial web services. The solution relies on semantic web services technology and Artificial Intelligence (AI) planning techniques to generate composite geospatial web services. Web Service Modelling Ontology (WSMO) is selected as the underlying semantic web service framework. A neoclassical planning algorithm called Graphplan is used as the AI planner. The applicability of the proposed solution for composing web services is illustrated in a case study. The result shows that the proposed approach is well suited for the automatic composition of web services. The future requirements for adaptation of the approach in real world problems are broadly described.

Automatic composition of WSMO based geospatial semantic web services using artificial intelligence planning

In this paper, we present a Petri net-based approach for modeling the choreography of semantic Web services which are described following the OWL-S specification. In our approach, each control construct of the OWL-S choreography is represented through a Petri net pattern that captures formally its operational semantics. The main difference between our work and the main proposals that model the semantics of OWL-S services choreography is that, although both approaches represent the service choreography with Petri nets, our proposal is also concerned with the practical execution of the Petri nets by the client. Therefore we also represent the flow of data, the outputs transformations, the effects in the environment, in addition to the structures that control the choreography of the services in our Petri net models. The implementation of the OWL-S choreography is performed in a Petri net ontology-based engine. This is another difference with traditional approaches that only use Petri nets for the analysis of the service properties. Furthermore, the use of an underlying ontology engine for supporting both the domain models of OWL-S services and the Petri net models provides several advantages in terms of reasoning, extension, and reuse.

Toward the use of Petri nets for the formalization of OWL-S choreographies

With the exponential growth in available web services and diversity of user needs, automatic web service selection and composition techniques have attracted the attention of many researchers. This paper presents a fluent calculus-based, context-aware web service composition model. The model uses an artificial intelligence (AI) planning-based web service composition technique, which translates web service composition problems into AI planning problems, and then achieves target goals by acquisition and reasoning using existing environmental knowledge. We first construct a model for service, service context, and service composition on the basis of the fluent calculus theory. Then, we extend the basic axioms of the fluent calculus (initial state and state update axioms) to describe context information, an approach that endows context-aware ability to the fluent calculus-based web service composition. Furthermore, we implement a fluent calculus-based, context-aware web service composition model using a fluent calculus executor or FLUX in a digital tourism service scenario. The experimental results show that the proposed model has context-aware capability and exhibits better performance in service composition.

http://www.aicit.org/aiss/ppl/0_AISS_Binder_08_8.pdf

Research on Context-aware Web Service Composition based on the Fluent Calculus

Service-Oriented Architecture (SOA) has emerged as a prominent design style that enables an IT infrastructure to allow different applications to participate in business processes, regardless of their underlying features, by encapsulating them as platform-independent entities that become available via a certain network, primarily the Internet. In order to effectively discover and use the most suitable services, service description should provide a complete behavior model, describing the inputs and preconditions that are required before execution, as well as the outputs and effects of a successful execution. Such service specifications are indispensable in a variety of activities, such as conformance and verification checks, adaptation evaluation and deducing composability of services. Service specifications rely on the expression of conditions that should hold before and after service execution. Such specifications are prone to a family of problems, known in the AI literature as the frame, ramification and qualification problems. These problems deal with the succinct and flexible representation of non-effects, indirect effects and preconditions, respectively. Research in services has largely ignored these problems, at the same time ignoring their effects, such as compromising the integrity and correctness of services and service compositions and the inability to provide justification for unexpected execution results. To address these issues, this thesis proposes the Web Service Specification Language (WSSL), a novel, semantics-aware language for the specification and composition of services, independent of service design models. WSSL’s foundation is the fluent calculus, a specification language for robots that offers solutions

A novel specification and composition language for services

This paper presents a novel approach for semantic web service composition based on the formalism of fluent calculus. We show how the planning capabilities of the fluent calculus can be used to automatically generate an abstract composition model . For describing the capabilities of web services we have used an OWL-S ontology. Based on the OWL-S ontology semantics, we encode the web service description in the fluent calculus formalism and provide a planning strategy for service composition. To test our composition method, we have implemented an experimental framework that automatically composes and executes web services. Our approach is similar with McIlraiths [2] in terms of computational model, both approaches having the roots in the theory of situation calculus, but the two solutions are complementary. In the situation calculus, the successor state axioms describe how a particular fluent may be changed by an action, whereas the state update axioms of the fluent calculus describe which fluents are changed by an action. The two approaches also differ in the way to evaluate the conditions in the programming languages (GOLOG and FLUX) that implement the two formalisms. For condition evaluation, GOLOG applies the principle of regression, while FLUX [3] uses the principle of progression. Using regression is efficient for short action sequences, but the computational effort increases with the number of performed actions, while by using progression, the computational effort remains the same, independently of the number of performed actions.

Simona Manole

Papers

Fluent Calculus Based Web Service Composition