A semantic description framework for web services descriptions and matchmaking

In the M.Sc thesis, the project focuses on the problems of semantic-based representing and retrieving Web services based on the capabilities of services. Service description is critical to application development in Web service environments. There are a number of motivated research developed for representing Web services by different research organisations such as WSDL and UDDI. Both of them are existing standards for Web services. WSDL is designed to provide descriptions of message transport and interface used by each service. UDDI provides a registration structure for businesses and services, and describes businesses and services using their physical attributes in terms of names, addresses, human-understandable business descriptions and service descriptions. Both WSDL and UDDI lack semantic-based description information and a number of essential factors of service capabilities are out of the current description frameworks such as the degrees of service capabilities, relationships between users and services. Moreover, the discovery mechanism provided by UDDI is "exact match” search on the business or service names and descriptions. Actually, service providers and service consumers may have very different background and knowledge, so they do not usually share the same description information for the same item in their minds. It is difficult to locate the proper Web services if users do not express their requirements exactly same with the service provider advertisements. With the consideration of above problems, the development of techniques to semantically represent Web services is necessary for the Web service description and matchmaking. To address the above problems, we identify several requirements and essential factors that a Web service description framework should have and propose a semantic rich modelling framework to integrate these factors to describe Web services capabilities in unambiguous and computer-understandable forms with ontology. The novel description framework is the Business-Service-User (BSU) framework which provides a semantic based description information for business, service and user. Another important goal for the BSU framework is to integrate with current Semantic Web markup languages so that the framework can be easily accessed and understood by the computer. In this thesis, we use the semantic web language OWL to represent the BSU framework and the new semantic description language is called OWL-BSU, which is a computer-interpretable description of the business, service and user. Moreover, a simple and effective matching algorithm is designed to calculate the semantic relationships between service consumers requirements and service descriptions. To make our approach work in the real world, we develop a semantic Web services search engine, which integrates OWL-BSU and the matching algorithm on the top of UDDI registry. The evaluation experimental results have shown that our approach can achieve a great improvement on retrieval performance in terms of recall and precision, comparable to the existing UDDI registry

Ontology for service oriented testing of web services

This paper presents a service oriented architecture for testing Web Services. In this architecture, various parties interoperate with each other to complete testing tasks through testing service registration, discovery and invocation. The analysis of the architecture in a typical scenario shows that it has the advantages of supporting dynamic discovery and invocation of testing services as required by the dynamic discovery and invocation of normal functional services without compromising security, privacy and intellectual property rights. It is flexibleand extendable. It also helps to reduce the risk ofunnecessary disturbances to the normal operations of services due to testing activities. The paper reports a prototype implementation of the architecture by adapting and implementing the ontology of software testing using Semantic Web Services technology. A case studywith the WS wrapping of an automated testing tool is also reported, which demonstrated that the architecture is technically feasible

An intelligent framework for dynamic web services composition in the semantic web

As Web services are being increasingly adopted as the distributed computing technology of choice to securely publish application services beyond the firewall, the importance of composing them to create new, value-added service, is increasing. Thus far, the most successful practical approach to Web services composition, largely endorsed by the industry falls under the static composition category where the service selection and flow management are done a priori and manually. The second approach to web-services composition aspires to achieve more dynamic composition by semantically describing the process model of Web services and thus making it comprehensible to reasoning engines or software agents. The practical implementation of the dynamic composition approach is still in its infancy and many complex problems need to be resolved before it can be adopted outside the research communities. The investigation of automatic discovery and composition of Web services in this thesis resulted in the development of the eXtended Semantic Case Based Reasoner (XSCBR), which utilizes semantic web and AI methodology of Case Based Reasoning (CBR). Our framework uses OWL semantic descriptions extensively for implementing both the matchmaking profiles of the Web services and the components of the CBR engine. In this research, we have introduced the concept of runtime behaviour of services and consideration of that in Web services selection. The runtime behaviour of a service is a result of service execution and how the service will behave under different circumstances, which is difficult to presume prior to service execution. Moreover, we demonstrate that the accuracy of automatic matchmaking of Web services can be further improved by taking into account the adequacy of past matchmaking experiences for the requested task. Our XSCBR framework allows annotating such runtime experiences in terms of storing execution values of non-functional Web services parameters such as availability and response time into a case library. The XSCBR algorithm for matchmaking and discovery considers such stored Web services execution experiences to determine the adequacy of services for a particular task. We further extended our fundamental discovery and matchmaking algorithm to cater for web services composition. An intensive knowledge-based substitution approach was proposed to adapt the candidate service experiences to the requested solution before suggesting more complex and computationally taxing AI-based planning-based transformations. The inconsistency problem that occurs while adapting existing service composition solutions is addressed with a novel methodology based on Constraint Satisfaction Problem (CSP). From the outset, we adopted a pragmatic approach that focused on delivering an automated Web services discovery and composition solution with the minimum possible involvement of all composition participants: the service provider, the requestor and the service composer. The qualitative evaluation of the framework and the composition tools, together with the performance study of the XSCBR framework has verified that we were successful in achieving our goal

A service concept recommendation system for enhancing the dependability of semantic service matchmakers in the service ecosystem environment

A Service Ecosystem is a biological view of the business and software environment, which is comprised of a Service Use Ecosystem and a Service Supply Ecosystem. Service matchmakers play an important role in ensuring the connectivity between the two ecosystems. Current matchmakers attempt to employ ontologies to disambiguate service consumers’ service queries by semantically classifying service entities and providing a series of human computer interactions to service consumers. However, the lack of relevant service domain knowledge and the wrong service queries could prevent the semantic service matchmakers from seeking the service concepts that can be used to correctly represent service requests. To resolve this issue, in this paper, we propose the framework of a service concept recommendation system, which is built upon a semantic similarity model.This system can be employed to seek the concepts used to correctly represent service consumers’ requests, when a semantic service matchmaker finds that the service concepts that are eventually retrieved cannot match the service requests. Whilst many similar semantic similarity models have been developed to date, most of them focus on distance-based measures for the semantic network environment and ignore content-based measures for the ontology environment. For the ontology environment in which concepts are defined with sufficient datatype properties, object properties, and restrictions etc., the content of concepts should be regarded as an important factor in concept similarity measures. Hence, we present a novel semantic similarity model for the service ontology environment. The technical details and evaluation details of the framework are discussed in this paper

Integrating Protein Data Resources through Semantic Web Services

Understanding the function of every protein is one major objective of bioinformatics. Currently, a large amount of information (e.g., sequence, structure and dynamics) is being produced by experiments and predictions that are associated with protein function. Integrating these diverse data about protein sequence, structure, dynamics and other protein features allows further exploration and establishment of the relationships between protein sequence, structure, dynamics and function, and thereby controlling the function of target proteins. However, information integration in protein data resources faces challenges at technology level for interfacing heterogeneous data formats and standards and at application level for semantic interpretation of dissimilar data and queries. In this research, a semantic web services infrastructure, called Web Services for Protein data resources (WSP), for flexible and user-oriented integration of protein data resources, is proposed. This infrastructure includes a method for modeling protein web services, a service publication algorithm, an efficient service discovery (matching) algorithm, and an optimal service chaining algorithm. Rather than relying on syntactic matching, the matching algorithm discovers services based on their similarity to the requested service. Therefore, users can locate services that semantically match their data requirements even if they are syntactically distinctive. Furthermore, WSP supports a workflow-based approach for service integration. The chaining algorithm is used to select and chain services, based on the criteria of service accuracy and data interoperability. The algorithm generates a web services workflow which automatically integrates the results from individual services.A number of experiments are conducted to evaluate the performance of the matching algorithm. The results reveal that the algorithm can discover services with reasonable performance. Also, a composite service, which integrates protein dynamics and conservation, is experimented using the WSP infrastructure

Atomic service-based scheduling for web services composition

With the rapid development of Internet technologies and widespread of Internet applications, Web Services has become an important research issue of World Wide Web Consortium (W3C). In order to cope with various requirements from service users, services need to be thoroughly and precisely described, thus improvement needs to be made in describing services as more properties should be added to the current service description model based on OWL-ร, an ontology structure consisting of service profiles and operations. Semantics is widely considered as one of the core supplements, which is able to provide the metadata of services, so as to better match requirements with services in the service repository. On the other hand, Web Services has attracted people from various fields to perform relevant experiments on how to cope with users' requirements. Service providers tend to coordinate service implementation by means of interacting with available resources and reconstructing existing service modules. The integration of self-contained software components becomes a key step to meet service demands. This thesis makes contributions to current service description. The introduction of the term "Atomic Service" is not only considered to be a more refined service structure, but also serves as the fundamental component for all service modules. Based on this, the thesis will discuss issues including composition and scheduling, with the purpose of building interoperations among composable service units and setting up the mechanism of realising business goals with composite services under the guidance of the service scheduling language. This notion is illustrated in a demonstration system to justify the manageable interrelationship between service modules and the way of composition

Correctness-aware high-level functional matching approaches for semantic web services

Existing service matching approaches trade precision for recall, creating the need for humans to choose the correct services, which is a major obstacle for automating the service matching and the service aggregation processes. To overcome this problem, the matchmaker must automatically determine the correctness of the matching results according to the defined users' goals. That is, only service(s)-achieving users' goals are considered correct. This requires the high-level functional semantics of services, users, and application domains to be captured in a machine-understandable format. Also this requires the matchmaker to determine the achievement of users' goals without invoking the services. We propose the G+ model to capture the high-level functional specifications of services and users (namely goals, achievement contexts and external behaviors) providing the basis for automated goal achievement determination; also we propose the concepts substitutability graph to capture the application domains' semantics. To avoid the false negatives resulting from adopting existing constraint and behavior matching approaches during service matching, we also propose new constraint and behavior matching approaches to match constraints with different scopes, and behavior models with different number of state transitions. Finally, we propose two correctness-aware matching approaches (direct and aggregate) that semantically match and aggregate semantic web services according to their G+ models, providing the required theoretical proofs and the corresponding verifying simulation experiments

Semantic Service Description Framework for Efficient Service Discovery and Composition

Web services have been widely adopted as a new distributed system technology by industries in the areas of, enterprise application integration, business process management, and virtual organisation. However, lack of semantics in current Web services standards has been a major barrier in the further improvement of service discovery and composition. For the last decade, Semantic Web Services have become an important research topic to enrich the semantics of Web services. The key objective of Semantic Web Services is to achieve automatic/semi-automatic Web service discovery, invocation, and composition. There are several existing semantic Web service description frameworks, such as, OWL-S, WSDL-S, and WSMF. However, existing frameworks have several issues, such as insufficient service usage context information, precisely specified requirements needed to locate services, lacking information about inter-service relationships, and insufficient/incomplete information handling, make the process of service discovery and composition not as efficient as it should be. To address these problems, a context-based semantic service description framework is proposed in this thesis. This framework focuses on not only capabilities of Web services, but also the usage context information of Web services, which we consider as an important factor in efficient service discovery and composition. Based on this framework, an enhanced service discovery mechanism is proposed. It gives service users more flexibility to search for services in more natural ways rather than only by technical specifications of required services. The service discovery mechanism also demonstrates how the features provided by the framework can facilitate the service discovery and composition processes. Together with the framework, a transformation method is provided to transform exiting service descriptions into the new framework based descriptions. The framework is evaluated through a scenario based analysis in comparison with OWL-S and a prototype based performance evaluation in terms of query response time, the precision and recall ratio, and system scalability

Grid-based semantic integration of heterogeneous data resources: Implementation on a HealthGrid

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.The semantic integration of geographically distributed and heterogeneous data resources still remains a key challenge in Grid infrastructures. Today's mainstream Grid technologies hold the promise to meet this challenge in a systematic manner, making data applications more scalable and manageable. The thesis conducts a thorough investigation of the problem, the state of the art, and the related technologies, and proposes an Architecture for Semantic Integration of Data Sources (ASIDS) addressing the semantic heterogeneity issue. It defines a simple mechanism for the interoperability of heterogeneous data sources in order to extract or discover information regardless of their different semantics. The constituent technologies of this architecture include Globus Toolkit (GT4) and OGSA-DAI (Open Grid Service Architecture Data Integration and Access) alongside other web services technologies such as XML (Extensive Markup Language). To show this, the ASIDS architecture was implemented and tested in a realistic setting by building an exemplar application prototype on a HealthGrid (pilot implementation). The study followed an empirical research methodology and was informed by extensive literature surveys and a critical analysis of the relevant technologies and their synergies. The two literature reviews, together with the analysis of the technology background, have provided a good overview of the current Grid and HealthGrid landscape, produced some valuable taxonomies, explored new paths by integrating technologies, and more importantly illuminated the problem and guided the research process towards a promising solution. Yet the primary contribution of this research is an approach that uses contemporary Grid technologies for integrating heterogeneous data resources that have semantically different. data fields (attributes). It has been practically demonstrated (using a prototype HealthGrid) that discovery in semantically integrated distributed data sources can be feasible by using mainstream Grid technologies, which have been shown to have some Significant advantages over non-Grid based approaches