Використання технік AI-планування для вирішення задач композиції Веб-сервісів

Автоматична композиція сервісів, що представлені процесною моделлю, складна, але дуже актуальна задача, вирішення якої потребує, перш за все строгої формалізації та суттєвої семантизації опису сервісу. Схожість визначення задач інтелектуального планування до задач композиції сервісів доводить можливість застосування підходів AI-планування до вирішення проблем композиції Веб-сервісів, за умови вирішення низки проблем. В даній роботі проводиться аналіз схожості та розбіжностей задач HTN- планування та композиції Веб-сервісів, що представлені процесною моделлю, а саме BPEL- сервісів, визначаються основні проблеми щодо безпосереднього застосування технік AI-планування та пропонуються підходи до їх вирішення, шляхом інтеграції дескриптивної логіки та методів HTN-планування, а також пропонуються підходи до трансляції BPEL описів у HTN-DL.Автоматизированная композиция сервисов, представленных процессной моделью, является сложной, но на сегодняшний день очень насущной задачей. Ее решение требует, прежде всего, строгой формализации и сильной семантизации представления сервиса. Подобие определений задач интеллектуального планирования и задач композиции сервисов доказывает возможность применения подходов AI-планирования к решению проблем композиции Веб-сервисов, при условии решения ряда имеющихся проблем. В данной работе проводится анализ схожести и различий задач HTN- планирования и композиции Веб-сервисов, представленных процессной моделью, а именно BPEL- сервисов, определяются основные проблемы, возникающие при непосредственном применении техник AI-планирования и предлагаются подходы к их решению путем интеграции дескриптивной логики и методов HTN-планирования, а также предлагаются подходы к трансляции BPEL описаний в HTN-DL.Automated composition of services described by their process model is difficult but very vital task. Its decision needs strict formalization and strong semantization of a service. Similarity of definitions of intelligent planning tasks and services composition objectives demonstrates the possibility of using AI-planning approaches for resolving Web services composition problems, provided a number of solutions to existing problems. In this article the analysis of task similarity and differences of HTN-planning and composition of Web-services presented by process model is executed. BPEL-services are considered. It is defined main problems that appears when AI-planning methods are used and it is proposed approaches for their resolving by integration DL and HTN-planning. Translation algorithms from BPEL to HTN-DL is also discussed

Backwards State-space Reduction for Planning in Dynamic Knowledge Bases

In this paper we address the problem of planning in rich domains, where knowledge representation is a key aspect for managing the complexity and size of the planning domain. We follow the approach of Description Logic (DL) based Dynamic Knowledge Bases, where a state of the world is represented concisely by a (possibly changing) ABox and a (fixed) TBox containing the axioms, and actions that allow to change the content of the ABox. The plan goal is given in terms of satisfaction of a DL query. In this paper we start from a traditional forward planning algorithm and we propose a much more efficient variant by combining backward and forward search. In particular, we propose a Backward State-space Reduction technique that consists in two phases: first, an Abstract Planning Graph P is created by using the Abstract Backward Planning Algorithm (ABP), then the abstract planning graph P is instantiated into a corresponding planning graph P by using the Forward Plan Instantiation Algorithm (FPI). The advantage is that in the preliminary ABP phase we produce a symbolic plan that is a pattern to direct the search of the concrete plan. This can be seen as a kind of informed search where the preliminary backward phase is useful to discover properties of the state-space that can be used to direct the subsequent forward phase. We evaluate the effectiveness of our ABP+FPI algorithm in the reduction of the explored planning domain by comparing it to a standard forward planning algorithm and applying both of them to a concrete business case study.Comment: In Proceedings GRAPHITE 2014, arXiv:1407.767

OWL-POLAR : A Framework for Semantic Policy Representation and Reasoning

Peer reviewedPreprin

Семантична анотація Веб-сервісів

Важливість опису Веб-сервісів на рівні процесів та створення механізмів для роботи з такими описами широко визнана. Визначення та розуміння клієнтом семантик кожного елементу такого процесу забезпечує можливість їх адекватного вибору та застосування. Використання та формалізація семантичних анотацій відкриває шлях до автоматизованого вирішення такої складної задачі Веб-сервісів, як їх композиція. В даній роботі визначається роль анотацій. Типи семантик, що надаються в анотаціях, розглядаються у взаємозв’язку з існуючими задачами Веб-сервісів на всіх етапах їх життєвого циклу. При цьому Веб-сервіс розглядається як з точки зору даних, так і поведінки. Наведені основні етапи анотування. Розглядається проблема мінімізації анотацій, як механізму підвищення ефективності вирішення проблем Веб-сервісів. Визначається місце та роль дескриптивних логік в семантизації Веб-сервісів

Research Article Novel Security Conscious Evaluation Criteria for Web Service Composition

Abstract: This study aims to present a new mathematical based evaluation method for service composition with respects to security aspects. Web service composition as complex problem solver in service computing has become one of the recent challenging issues in today's web environment. It makes a new added value service through combination of available basic services to address the problem requirements. Despite the importance of service composition in service computing, security issues have not been addressed in this area. Considering the dazzling growth of number of service based transactions, making a secure composite service from candidate services with different security concerns is a demanding task. To deal with this challenge, different techniques have been employed which have direct impacts on secure service composition efficiency. Nonetheless, little work has been dedicated to deeply investigate those impacts on service composition outperformance. Therefore, the focus of this study is to evaluate the existing approaches based on their applied techniques and QoS aspects. A mathematicalbased security-aware evaluation framework is proposed wherein Analytic Hierarchy Process (AHP), a multiple criteria decision making technique, is adopted. The proposed framework is tested on state-of-the-art approaches and the statistical analysis of the results presents the efficiency and correctness of the proposed work

ABSTRACT Title of dissertation: COMBINING DESCRIPTION LOGIC REASONING WITH AI PLANNING FOR COMPOSITION OF WEB SERVICES

As Web Services become more prevalent — with the aim of achieving inter-operability between heterogeneous, decentralized and distributed systems — the problem of selecting and composing services to accomplish a given task becomes more important. Using Web ontologies to describe different properties of Web Ser-vices provided by separate developers facilitates their integration. Automating the composition of Web Services is essential for various different subjects ranging from ordinary users performing tasks on the Web, businesses carrying out complex trans-actions, and scientists collaborating with each other on the computational Grid. In this thesis I present the HTN-DL formalism which combines Hierarchical Task Network (HTN) planning and Description Logics (DL) to automatically com-pose Web Services which are described with Web Ontology Language (OWL). The main contributions of this thesis are as follows: • The HTN-DL formalism, which couples Hierarchical Task Network (HTN) planning and Description Logics. HTN-DL combines the expressivity of De-scription Logics with the efficiency of HTN planning systems to solve We

Reasoning Algebraically with Description Logics

Semantic Web applications based on the Web Ontology Language (OWL) often require the use of numbers in class descriptions for expressing cardinality restrictions on properties or even classes. Some of these cardinalities are specified explicitly, but quite a few are entailed and need to be discovered by reasoning procedures. Due to the Description Logic (DL) foundation of OWL, those reasoning services are offered by DL reasoners. Existing DL reasoners employ reasoning procedures that are arithmetically uninformed and substitute arithmetic reasoning by "don't know" non-determinism in order to cover all possible cases. This lack of information about arithmetic problems dramatically degrades the performance of DL reasoners in many cases, especially with ontologies relying on the use of Nominals and Qualied Cardinality Restrictions. The contribution of this thesis is twofold: on the theoretical level, it presents algebra�ic reasoning with DL (ReAl DL) using a sound, complete, and terminating reasoning procedure for the DL SHOQ. ReAl DL combines tableau reasoning procedures with algebraic methods, namely Integer Programming, to ensure arithmetically better informed reasoning. SHOQ extends the standard DL ALC with transitive roles, role hierarchies, qualified cardinality restrictions (QCRs), and nominals, and forms an expressive subset of OWL. Although the proposed algebraic tableau is double exponential in the worst case, it deals with cardinalities with an additional level of information and properties that make the calculus amenable and well suited for optimizations. In order for ReAl DL to have a practical merit, suited optimizations are proposed towards achieving an efficient reasoning approach that addresses the sources of complexity related to nominals and QCRs. On the practical level, a running prototype reasoner (HARD) is implemented based on the proposed calculus and optimizations. HARD is used to evaluate the practical merit of ReAl DL, as well as the effectiveness of the proposed optimizations. Experimental results based on real world and synthetic ontologies show that ReAl DL outperforms existing reasoning approaches in handling the interactions between nominals and QCRs. ReAl DL also comes with some interesting features such as the ability to handle ontologies with cyclic descriptions without adopting special blocking strategies. ReAl DL can form a basis to provide more efficient reasoning support for ontologies using nominals or QCRs