Semantic Web Service Composition via Logic-based Program Synthesis

The ability to efficient selection and integration of inter-organizational heterogeneous Web services at runtime becomes an important requirement to the Web service provision. In an Web service application, if no single existing Web service can satisfy the functionality required by the user, there should be a program or an agent to automated combine existing services together in order to fulfill the request. The aim of this thesis is to consider the Web service composition problem from the viewpoint of logic-based program synthesis, and to propose an agent-based framework for supporting the composition process in scalable and flexible manner. The approach described in this thesis uses Linear Logic-based theorem proving to assist and automate composition of Semantic Web services. The approach uses a Semantic Web service language (DAML-S) for external presentation of Web services, while, internally, the services are presented by extralogical axioms and proofs in Linear Logic. Linear Logic, as a resource conscious logic, enables us to capture the concurrent features of Web services formally (including parameters, states and non-functional attributes). The approach uses a process calculus to present the process model of the composite service. The process calculus is attached to the Linear Logic inference rules in the style of type theory. Thus the process model for a composite service can be generated directly from the complete proof. We introduce a set of subtyping rules that defines a valid dataflow for composite services. The subtyping rules that are used for semantic reasoning are presented with Linear Logic inference figures. The composition system has been implemented based on a multi-agent architecture, AGORA. The agent-based design enables the different components for Web service composition system, such as the theorem prover, semantic reasoner and translator to integrated to each other in a loosely coupled manner. We conclude with discussing how this approach has been directed to meet the main challenges in Web service composition. First, it is autonomous so that the users do not required to analyze the huge amount of available services manually. Second, it has good scalability and flexibility so that the composition is better performed in a dynamic environment. Third, it solves the heterogeneous problem because the Semantic Web information is used for matching and composing Web services. We argue that LL theorem proving, combined with semantic reasoning offers a practical approach to the success to the composition of Web services. LL, as a logic for specifying concurrent programming, provides higher expressive powers in the modeling of Web services than classical logic. Further, the agent-based design enables the different components for Web service composition system to integrated to each other in a loosely coupled manner. The main contributions of this thesis is summarized as follows. First, an generic framework is developed for the purpose of presenting an abstract process of the automated Semantic Web service composition. Second, a specific system based on the generic platform has been developed. The system focuses on the translation between the internal and external languages together with the process extraction from the proof. Third, applications of the subtyping inference rules that are used for semantic reasoning is discussed. Fourth, an agent architecture is developed as the platform for Web service provision and composition

Interleaving Semantic Web Reasoning and Service Discovery to Enforce Context-Sensitive Security and Privacy Policies

Abstract. Enforcing rich policies in open environments will increasingly require the ability to dynamically identify external sources of information necessary to enforce different policies (e.g. finding an appropriate source of location information to enforce a location-sensitive access control policy). In this paper, we introduce a semantic web framework and a metra-control model for dynamically interleaving policy reasoning and external service discovery and access. Within this framework, external sources of information are wrapped as web services with rich semantic profiles allowing for the dynamic discovery and comparison of relevant sources of information. Each entity (e.g. user, sensor, application, or organization) relies on one or more Policy Enforcing Agents responsible for enforcing relevant privacy and security policies in response to incoming requests. These agents implement meta-control strategies to dynamically interleave semantic web reasoning and service discovery and access. The paper also presents preliminary empirical results. This research has been conducted in the context of myCampus, a pervasive computing environment aimed at enhancing everyday campus life at Carnegie Mellon University. The framework presented can be extended to a range of other applications requiring the enforcement of context-sensitive policies (e.g. virtual enterprises, coalition forces, homeland security, etc.)

Toward the composition of semantic web services

Abstract. This paper introduces a method for automatic composition of semantic web services using linear logic theorem proving. The method uses semantic web service language (DAML-S) for external presentation of web services, and, internally, the services are presented by extralogical axioms and proofs in linear logic. Linear logic(LL)[2], as a resource conscious logic, enables us to define the attributes of web services formally (in particular, qualitative and quantitative value of non-functional attributes). The subtyping rules that are used for semantic reasoning are presented as linear logic implication. We propose a system architecture where the DAML-S parser, linear logic theorem prover and semantic reasoner can work together. This architecture has been implemented in Java programming language.

Logic-based web services composition: From service description to process model

This paper introduces a method for automatic composition of Semantic Web services using Linear Logic (LL) theorem proving. The method uses Semantic Web service language (DAML-S) for external presentation of Web services, while, internally, the services are presented by extralogical axioms and proofs in LL. We use a process calculus to present the composite service formally. The process calculus is attached to the LL inference rules in the style of type theory. Thus the process model for a composite service can be generated directly from the proof. The subtyping rules that are used for semantic reasoning are presented with LL inference figures. We propose a system architecture where the DAML-S translator, the LL theorem prover and the semantic reasoner can operate together to fulfill the task. This architecture has been implemented in Java. 1

Value-Added Web Services Composition Using Automatic Program Synthesis

Abstract. The number of products and services available over the Internet increases dramatically during the last years and it is already beyond the human ability to analyze and combine them efficiently. At the same time if we consider works in software engineering (and, in particular, in component-based system development) then we can find quite strong similarity in problem description. The web services can be treated in a way similar to software components and service composition can be considered as problem of software synthesis and composition. Basic idea of our approach is applying the software synthesis and composition methods to value added web services composition. We also describe some technical details within the approach, in particular, a web service description language and a program synthesis method.

A Survey of Automated Web Service Composition Methods

Abstract. In today’s Web, Web services are created and updated on the fly. It’s already beyond the human ability to analysis them and generate the composition plan manually. A number of approaches have been proposed to tackle that problem. Most of them are inspired by the researches in cross-enterprise workflow and AI planning. This paper gives an overview of recent research efforts of automatic Web service composition both from the workflow and AI planning research community.