Bi-Level Selection Model for Web Services Search

Service registries and web service engines are the main approaches for discovering web services. Current service directories are mainly based on Universal Description, Discovery and Integration (UDDI), which is an industry standard for service registries, developed to solve the web service search problem. However, UDDI offers limited search functionalities which may return a huge number of irrelevant services. Another critical challenge in web service search and composition is the selection of web services, to be executed or to be composed, from the pool of matching services. Most of the current service selection proposals apply a weighted sum model (WSM) as an evaluation method for selection of services with the same functionality. In this paper, we propose a Bi-level service selection approach that selects the most appropriate web services from the pool of matching services that considers both the functional and non-functional requirements for service selection. The functional requirements are provided by the user as a set of input parameters provided for and output parameters desired from the web service. The user also provides a set of desired QoS values and the order of their preference for selection. The experimental results demonstrate the efficiency of service search in our bi-level model and the variety of user queries supported

Extended Service Registry for Efficient Web Service Search

Service registries and web service engines are the main approaches for discovering web services. Current service directories are mainly based on Universal Description, Discovery and Integration (UDDI), which is an industry standard for service registries, developed to solve the web service search problem. However, UDDI offers limited search functionalities which may return a huge number of irrelevant services. Often consumers may be unaware of precise keywords to retrieve the required services satisfactorily and may be looking for services capable of providing certain outputs. In this paper, we propose a new system called Extended Service Registry (ESR) for extended and efficient service search using an object relational database. The functional requirements are provided by the user as a set of input parameters provided for and output parameters desired from the web service. The experimental results demonstrate the efficiency of service search in our Extended Service Registry (ESR) and the variety of user queries supported

Using a private UDDI for publishing location-based information to mobile users

This paper describes our experience with the use of Universal Description, Discovery and Integration (UDDI) technology for supporting location-based service discovery. Our goal is to allow Web Services to be associated with physical locations and then queried according to spatial criteria. This would enable location-based applications to use local UDDI registries to discover the Web Services that are relevant for the current location of a mobile user. However, the current model for Web Services discovery in UDDI does not directly support the particular requirements of location-based discovery. The main limitation is the inadequacy of the query-processing mechanism, based on exact matching between query criteria and service categorizations, to support discovery models based on proximity. We propose an approach that includes a space model that allows external entities to obtain information about the spatial structure of the local environment, a set of querying taxonomies that allow UDDI queries to include spatial criteria while maintaining conformance with the UDDI standards, and a proxy that allows application to benefit from spatial queries while maintaining the approach transparent. This approach is currently being used and evaluated in the VADE project

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

Web service-based exploration of Earth Observation time-series data for analyzing environmental changes

The increasing amount of Earth observation (EO) data requires a tremendous change, in order to property handle the number of observations and storage size thereof. Due to open data strategies and the increasing size of data archives, a new market has been developed to provide analysis and application-ready data, services, and platforms. It is not only scientists and geospatial processing specialists who work with EO data; stakeholders, thematic experts, and software developers do too. There is thus a great demand for improving the discovery, access, and analysis of EO data in line with new possibilities of web-based infrastructures. With the aim of bridging the gap between users and EO data archives, various topics have been researched: 1) user requirements and their relation to web services and output formats; 2) technical requirements for the discovery and access of multi-source EO time-series data, and 3) management of EO time-series data focusing on application-ready data. Web services for EO data discovery and access, time-series data processing, and EO platforms have been reviewed and related to the requirements of users. The diversity of data providers and web services requires specific knowledge of systems and specifications. Although service specifications for the discovery of EO data exist, improvements are still necessary to meet the requirements of different user personas. For the processing of EO time-series data, various data formats and processing steps need to be handled. Still, there remains a gap between EO time-series data access and analysis tools, which needs to be addressed to simplify work with such data. Within this thesis, web services for the discovery, access, and analysis of EO time-series data have been described and evaluated based on different user requirements. Standardized web services specifications, output and data formats are proposed, introduced and described to meet the needs of the different user personas

QoS-aware Mobile Web Services Discovery Using Utility Functions

Existing QoS-aware Web Services discovery architectures tend to focus solely on fulfilling the requirements of either the client or the provider. However, the interests of the provider and client are not equivalent. The provider’s goal is to maximize the profit and consume the least amount of resources. On the other hand, the client’s selection is determined by their own requirements which do not always reflect the real resource overheads. This research aims to provide a novel mobile Web Services discovery and selection method based on utility functions to balance the requirements for clients and providers. In the mobile environment, it is critical to conserve resource consumption in addition to fulfilling user requirements, as resources such as wireless network bandwidth and mobile device power are precious. The proposed service selection strategy enables service providers to balance the cost/performance ratios and utilize the network bandwidth more effectively, while the clients can still attain the functional and quality levels specified in the service request

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

Defining and Prototyping a Life-cycle for Dynamic Service Composition

Since the Internet has become a commodity in both wired and wireless environments, new applications and paradigms have emerged to explore this highly distributed and widespread system. One such paradigm is service-orientation, which enables the provision of software functionality as services, \ud allowing in this way the construction of distributed systems with loosely coupled parts. The Service-Oriented Architecture (SOA) provides a set of principles to create service-oriented systems, by defining how services can be \ud created, composed, published, discovered and invoked. In accordance with these principles, in this paper we address the challenge of performing dynamic service composition. The composition process and its associated tasks have to be precisely defined so that the different problems of dynamic service composition can be identified and tackled. To achieve this, this paper defines a life-cycle for dynamic service composition, which defines the required phases and stakeholders. Furthermore, we present our prototype in which the different phases of the dynamic service composition life-cycle are being implemented. This prototype is being used to experiment with and validate our initial ideas on dynamic service composition

Towards runtime discovery, selection and composition of semantic services

Service-orientation is gaining momentum in distributed software applications, mainly because it facilitates interoperability and allows application designers to abstract from underlying implementation technologies. Service composition has been acknowledged as a promising approach to create composite services that are capable of supporting service user needs, possibly by personalising the service delivery through the use of context information or user preferences. In this paper we discuss the challenges of automatic service composition, and present DynamiCoS, which is a novel framework that aims at supporting service composition on demand and at runtime for the benefit of service end-users. We define the DynamiCoS framework based on a service composition life-cycle. Framework mechanisms are introduced to tackle each of the phases and requirements of this life-cycle. Semantic services are used in our framework to enable reasoning on the service requests issued by end users, making it possible to automate service discovery, selection and composition. We validate our framework with a prototype that we have built in order to experiment with the mechanisms we have designed. The prototype was evaluated in a testing environment using some use case scenarios. The results of our evaluation give evidences of the feasibility of our approach to support runtime service composition. We also show the benefits of semantic-based frameworks for service composition, particularly for end-users who will be able to have more control on the service composition process