Web Service Repository Research Articles

A novel and efficient index based web service discovery approach

Nowadays, with the expansion of the number of web services, the discovery and the selection of the latter are becoming complex tasks. To address this issue, different methods (indexing, clustering, database etc.) have been proposed in the literature so far. In this paper, we deal with index based methods to manage web service repositories. Indeed, using indexes perspective in web services discovery can help to promote the web service composition. Within this context, we propose a novel index method named Multi Level Sorted Index (MLSI) to improve the run time of the discovery process. The implementation and the simulation of our method have shown the efficiency of our approach in comparison with the inverted index and Multilevel Index Model (MLIM) in term of retrieval and addition times.

QoS aware web service selection using orthogonal array learning on fruit fly optimization approach

PurposeThis paper aims to solve the web service selection problem using an efficient meta-heuristic algorithm. The problem of selecting a set of web services from a large-scale service environment (web service repository) while maintaining Quality-of-Service (QoS), is referred to as web service selection (WSS). With the explosive growth of internet services, managing and selecting the proper services (or say web service) has become a pertinent research issue.Design/methodology/approachIn this paper, to address WSS problem, the authors propose a new modified fruit fly optimization approach, called orthogonal array-based learning in fruit fly optimizer (OL-FOA). In OL-FOA, they adopt a chaotic map to initialize the population; they add the adaptive DE/best/2mutation operator to improve the exploration capability of the fruit fly approach; and finally, to improve the efficiency of the search process (by reducing the search space), the authors use the orthogonal learning mechanism.FindingsTo test the efficiency of the proposed approach, a test suite of 2500 web services is chosen from the public repository. To establish the competitiveness of the proposed approach, it compared against four other meta-heuristic approaches (including classical as well as state-of-the-art), namely, fruit fly optimization (FOA), differential evolution (DE), modified artificial bee colony algorithm (mABC) and global-best ABC (GABC). The empirical results show that the proposed approach outperforms its counterparts in terms of response time, latency, availability and reliability.Originality/valueIn this paper, the authors have developed a population-based novel approach (OL-FOA) for the QoS aware web services selection (WSS). To justify the results, the authors compared against four other meta-heuristic approaches (including classical as well as state-of-the-art), namely, fruit fly optimization (FOA), differential evolution (DE), modified artificial bee colony algorithm (mABC) and global-best ABC (GABC) over the four QoS parameter response time, latency, availability and reliability. The authors found that the approach outperforms overall competitive approaches. To satisfy all objective simultaneously, the authors would like to extend this approach in the frame of multi-objective WSS optimization problem. Further, this is declared that this paper is not submitted to any other journal or under review.

Development of a Smart Technique for Mobile Web Services Discovery

Web service (WS) presents a good solution to the interoperability of different types of systems that aims to reduce the overhead of high processing in a resource-limited environment. With the increasing demand for mobile WS (MWS), the WS discovery process has become a significant challenging point in the WS lifecycle that aims to identify the relevant MWSs that best match the service requests. This discovery process is a resource-consuming task that cannot be performed efficiently in a mobile computing environment due to the limitations of mobile devices. Meanwhile, a cloud computing can provide rich computing resources for mobile environments given its unlimited and easily scalable resources. This paper proposes a semantic WS discovery and invocation framework in mobile environments based on cloud and a relationship-aware matchmaking algorithm. The discovery algorithm enriches MWS and user requests semantically with the functional and non-functional properties of Ontology Web Language for Services, such as Quality of Web Service, device context, and user preferences. The WS repository is filtered based on logical reasoning and a parameter-based matching algorithm to minimize the matching space and improve runtime performance. The cosine similarity between the user request and services repository is then assessed to generate the most relevant WS. The relationships among concepts in the ontology are considered to improve the recall and precision ratio. After the WS discovery process, users can invoke and test these services in a mobile environment through a dynamic user interface. The interface of the invocation process is changed according to the WS description document. An application prototype is also developed to evaluate the framework based on a Cordova cross-mobile development framework.

A Gen-Fuzzy Based Strategy (GFBS) for Web Service Classification

Service oriented computing makes great growth in developing web services. A web service is a software application with a standardized way of providing interoperability between disparate applications. Web service repository has a main challenging task in how it can help end user and another web service to group and retrieve their service with high performance. With increased number of both unrestricted and distributed services in web that belong to different domains, web services classification become necessary. This paper proposes a new classification strategy for web services called Gen-Fuzzy Based Strategy. The proposed strategy consists of two stages, which are; (i) Outlier Rejection Stage (ORS) and (ii) Classification Stage. In ORS, a proposed fuzzy system has been presented. It used four parameters which are; Distance to Class Center, Cooling Force, Class Belonging Degree and Domain Belonging Degree. In CS, a proposed Distance Based Ensemble Classifiers (DBEC) has been presented. The aim of DBEC is to train each individual classifier independently by using bagging technique. A collective decision is made by their aggregation in several ways. Experimental results have shown the effectiveness of DBEC in terms of accuracy, precision and recall.

System Design through the Exploration of Contemporary Web Services

In this article, we develop a Contemporary Web Service (CWS) repository of system designs, which are encoded as metadata of contemporary web services. We examine if this CWS repository serves as an effective design tool for initial CWS design and as an effective support tool for business users and analysts working together on system design. The CWS repository reduces the cognitive load of both the analyst and the business user as they jointly explore the CWS repository of system designs. It supports an evolutionary approach to system design through rapid selection of appropriate CWS metadata. To accomplish that, we introduce several new design characteristics for the CWS repository. The evaluation results demonstrate that the CWS repository is an effective tool for supporting designers during initial service design, as well as for supporting business users and analysts during system design.

Biological Web Service Repositories Review.

Web services play a key role in bioinformatics enabling the integration of database access and analysis of algorithms. However, Web service repositories do not usually publish information on the changes made to their registered Web services. Dynamism is directly related to the changes in the repositories (services registered or unregistered) and at service level (annotation changes). Thus, users, software clients or workflow based approaches lack enough relevant information to decide when they should review or re‐execute a Web service or workflow to get updated or improved results. The dynamism of the repository could be a measure for workflow developers to re‐check service availability and annotation changes in the services of interest to them. This paper presents a review on the most well‐known Web service repositories in the life sciences including an analysis of their dynamism. Freshness is introduced in this paper, and has been used as the measure for the dynamism of these repositories.

WSGM‐SD: An Approach to RESTful Service Discovery Based on Weighted Service Goal Model

Faced with the rapidly increasing Web services, it becomes a challenging issue for users to effectively and accurately discover and reuse services. Existing service discovery approaches are mainly developed for services with WSDL documents, while only a few attention is being paid to services described in natural language, especially to the RESTful services. Towards this issue, we introduce a Weighted service goal model (WSGM) by measuring the weights of service goals extracted from the textual descriptions of services. Based on the WSGM, a novel service discovery approach called Service discovery based on WSGM (WSGM-SD) is proposed. Experiments on ProgrammableWeb, a public Web service repository, demonstrate the effectiveness of the proposed approach.

E-Healthcare System based on Service oriented architecture With JavaScript Object Notation (Json) Framework

E-Healthcare simply refers to the use of electronic devices, mainly computer systems to help deliver healthcare services in a hospital. In eHealthcare, a number of systems are integrated in other to allow for rendering of healthcare services in a manner that minimizes the errors in the process as well as speed up the process. Recent researches on this topic show the lack of a proper underlying architecture or framework that allows the involvement of various stakeholders without sabotaging the security of the data and maintaining limited access control. This implies the need for a broader research into software architectures that will allow for the proper implementation of the eHealthcare system. In this paper, I introduce to you a new way of healthcare service delivery that is based on service oriented architecture. I started by presenting an in-depth literature review of an array of research documents published on eHealthcare in order to show the current state of the eHealthcare solutions and to present the absolute need for more research especially on the underlying architecture. Then, I proceed to propose my concept of eHealthcare called eHealthcare delivery system (e-HDS). It consists of basically three parts the eHDS node, the Web Service repository, the Web Service enabler/provider and the communication middleware. The web service repository is accessed through the web service enabler/provider which is implemented as a server on the web. The communication middleware is implemented based on service oriented architecture to provide controlled access to web services for the eHDS nodes. With e-HDS, various stakeholders like doctors, nurses, pharmacists, laboratories as well as patients will have controlled and secure access to a number of functionalities as well as a wide range of information that will otherwise be near impossible or unconventional and insecure.

Prefiltering Strategy to Improve Performance of Semantic Web Service Discovery

Discovery of semantic Web services is a heavyweight task when the number of Web services or the complexity of ontologies increases. In this paper, we present a new logical discovery framework based on semantic description of the capability of Web services and user goals using F-logic. Our framework tackles the scalability problem and improves discovery performance by adding two prefiltering stages to the discovery engine. The first stage is based on ontology comparison of user request and Web service categories. In the second stage, yet more Web services are eliminated based upon a decomposition and analysis of concept and instance attributes used in Web service capabilities and the requested capabilities of the client, resulting in a much smaller pool of Web services that need to be matched against the client request. Our prefiltering approach is evaluated using a new Web service repository, called WSMO-FL test collection. The recall rate of the filtering process is 100% by design, since no relevant Web services are ever eliminated by the two prefiltering stages, and experimental results show that the precision rate is more than 53%.

Distributed web service repository

The increasing availability and popularity of computer systems has resulted in a demand for new language- and platform-independent ways of data exchange. This demand has, in turn, led to significant growth in the importance of systems based on Web services. Alongside the growing number of systems accessible via Web services came the need for specialized data repositories that could oer eective means of searching the available services. The development of mobile systems and wireless data transmission technologies has allowed us to use dis- tributed devices and computer systems on a greater scale. The accelerating growth of distributed systems might be a good reason to consider the develop- ment of distributed Web service repositories with built-in mechanisms for data migration and synchronization.

Dynamic composition of Web services using efficient planners in large-scale service repository

Web services as independent software components are published by service providers over the Internet and invoked by service requesters for their desired functionalities. In many cases, however, there is no single service in a Web service repository satisfying a service request. So how to design an efficient method for composing a chain of connected services has become an important research issue. Recently, much research has been done into the search time reduction when finding a composite service. However, most methods take a long time for traversing all of the Web services in a service repository, thus it makes their response time significantly overrun a user’s waiting patience. This paper develops an efficient approach for automatic composition of Web services using the state-of-the-art Artificial Intelligence (AI) planners, where a Web service composition (WSC) problem is regarded as a WSC planning problem. Unlike most traditional WSC methods that traverse a Web service repository many times, our approach converts a Web service repository into a planning domain in PDDL just once, which will only be regenerated when the Web service repository changes. This treatment substantially reduces the response time and improves the scalability of solving WSC problems. We have implemented a prototype system and conducted extensive experiments on large-scale Web service repositories. The experimental results demonstrate that our proposed approach outperforms the state-of-the-art.

QoS-Aware Dynamic Composition of Web Services Using Numerical Temporal Planning

Web service composition (WSC) is the task of combining a chain of connected single services together to create a more complex and value-added composite service. Quality of service (QoS) has been mostly applied to represent nonfunctional properties of web services and differentiate those with the same functionality. Many research has been done on QoS-aware service composition, as it significantly affects the quality of a composite service. However, existing methods are restricted to predefined workflows, which can incur a couple of limitations, including the lack of guarantee for the optimality on overall QoS and for the completeness of finding a composite service solution. In this paper, instead of predefining a workflow model for service composition, we propose a novel planning-based approach that can automatically convert a QoS-aware composition task to a planning problem with temporal and numerical features. Furthermore, we use state-of-the-art planners, including an existing one and a self-developed one, to handle complex temporal planning problems with logical reasoning and numerical optimization. Our approach can find a composite service graph with the optimal overall QoS value while satisfying multiple global QoS constraints. We implement a prototype system and conduct extensive experiments on large web service repositories. The experimental results show that our proposed approach largely outperforms existing ones in terms of solution quality and is efficient enough for practical deployment.

Bootstrapping Ontologies for Web Services

Ontologies have become the de-facto modeling tool of choice, employed in many applications and prominently in the semantic web. Nevertheless, ontology construction remains a daunting task. Ontological bootstrapping, which aims at automatically generating concepts and their relations in a given domain, is a promising technique for ontology construction. Bootstrapping an ontology based on a set of predefined textual sources, such as web services, must address the problem of multiple, largely unrelated concepts. In this paper, we propose an ontology bootstrapping process for web services. We exploit the advantage that web services usually consist of both WSDL and free text descriptors. The WSDL descriptor is evaluated using two methods, namely Term Frequency/Inverse Document Frequency (TF/IDF) and web context generation. Our proposed ontology bootstrapping process integrates the results of both methods and applies a third method to validate the concepts using the service free text descriptor, thereby offering a more accurate definition of ontologies. We extensively validated our bootstrapping method using a large repository of real-world web services and verified the results against existing ontologies. The experimental results indicate high precision. Furthermore, the recall versus precision comparison of the results when each method is separately implemented presents the advantage of our integrated bootstrapping approach.

Eucalyptus Cloud to Remotely Provision e-Governance Applications

Remote rural areas are constrained by lack of reliable power supply, essential for setting up advanced IT infrastructure as servers or storage; therefore, cloud computing comprising an Infrastructure-as-a-Service (IaaS) is well suited to provide such IT infrastructure in remote rural areas. Additional cloud layers of Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS) can be added above IaaS. Cluster-based IaaS cloud can be set up by using open-source middleware Eucalyptus in data centres of NIC. Data centres of the central and state governments can be integrated with State Wide Area Networks and NICNET together to form the e-governance grid of India. Web service repositories at centre, state, and district level can be built over the national e-governance grid of India. Using Globus Toolkit, we can achieve stateful web services with speed and security. Adding the cloud layer over the e-governance grid will make a grid-cloud environment possible through Globus Nimbus. Service delivery can be in terms of web services delivery through heterogeneous client devices. Data mining using Weka4WS and DataMiningGrid can produce meaningful knowledge discovery from data. In this paper, a plan of action is provided for the implementation of the above proposed architecture.

An Efficient Web Service Discovery Architecture

There is been a continuous effort by the software developers to reduce cost and time to deliver the software and this has led to the advancements in service oriented paradigm. Organizations across all spectra have already deployed their main operations to the Web, which has brought about a fast growth of various Web services. This has dramatically increased the need to build a fundamental infrastructure for efficient deployment and access of the exponentially growing repository of Web services. Probably the most important aspect in dynamic web service access is the web service discovery. The challenge remains in handling and processing request queries and presenting the requester the most appropriate set of web service interfaces. Many approaches and frameworks have been proposed to discover web services. Some of the approaches assume that the requests are placed in SOAP compatible formats whereas some works are based on handling the plain text queries by their semantics while others focus on key word based query processing. We have tried to formulate an approach that uses the Principle of Compositionality of language to derive interface descriptions and aggregate or filter for their appropriateness. Going by lexical and syntactic structure of a language, a skeletally parsed corpus of a written piece of text has been used to resolve the plain text query. This paper also tries to propose an architecture based on x-SOA that the organizes the method of web service discovery in an efficient and structured manner using a intermediary, requester friendly layer called the Request Analyzer(abbreviated as RA) between the service provider and service requester via a service broker. We describe how the RA facilitates the processing of a plain text request query to finally being resolved to a most appropriate web service. We propose an algorithm for a complete cycle of web-service discovery. A cache based service broker approach has been proposed that consumes even lesser time towards discovery path. A reputation based mechanism has also been incorporated for keeping track of the trustworthiness and type of license of a web service being used and hence ensuring the authenticity for future use in terms of their past performances.

A monolithic approach to automated composition of semantic web services with the Event Calculus

In this paper, a web service composition and execution framework is presented for semantically -annotated web services. A monolithic approach to automated web service composition and execution problem is chosen, which provides some benefits by separating composition and execution phases. An AI planning method using a logical formalism, namely Abductive Event Calculus, is chosen for the composition phase. This formalism allows one to generate a narrative of actions and temporal orderings using abductive planning techniques given a goal. The functional properties of services, namely input/output/precondition/effects (IOPE) are taken into consideration in the composition phase and non-functional properties, namely Quality of Service (QoS) parameters are used in selecting the most appropriate solution to be executed. The repository of OWL-S semantic web services are translated to the Event Calculus axioms and the resulting plans found by the Abductive Event Calculus Planner are converted to graphs. These graphs can be sorted according to a score calculated using the defined quality of service parameters of the atomic services in the composition to determine the optimal solution. The selected graph is converted to an OWL-S file which is executed consequently.

A novel approach to annotating web service based on interface concept mapping and semantic expansion

With the rapid development of web service technology in these years, traditional standards have been matured during the process of service registry and discovery. However, it is difficult for service requesters to discover satisfactory web services. The reason for this phenomenon is that the traditional service organization mode lacks semantic understanding ability for service function interface. This paper proposes a novel approach to annotating web services. We first adopt domain ontology as a semantic context, and give our general framework of service semantic annotation. Then, interface concept mapping algorithm and service interface expansion algorithm are respectively presented in detail. Finally, the generation process of semantic web service repository is presented based on preceding algorithms. Simulation experiment results demonstrate that annotated web services by the proposed method can more satisfy requirements for service requesters than traditional ones by service matchmaking engine. It can get better service discovery effectiveness.

Context-Based Matching and Ranking of Web Services for Composition

In this work, we propose a two-step, context-based semantic approach to the problem of matching and ranking Web services for possible service composition. We present an analysis of different methods for classifying Web services for possible composition and supply a context-based semantic matching method for ranking these possibilities. Semantic understanding of Web services may provide added value by identifying new possibilities for compositions of services. The semantic matching ranking approach is unique since it provides the Web service designer with an explicit numeric estimation of the extent to which a possible composition ldquomakes sense.rdquo First, we analyze two common methods for text processing, TF/IDF and context analysis; and two types of service description, free text and WSDL. Second, we present a method for evaluating the proximity of services for possible compositions. Each Web service WSDL context descriptor is evaluated according to its proximity to other services' free text context descriptors. The methods were tested on a large repository of real-world Web services. The experimental results indicate that context analysis is more useful than TF/IDF. Furthermore, the method evaluating the proximity of the WSDL description to the textual description of other services provides high recall and precision results.

Graph Theoretic Topological Analysis of Web Service Networks

Using graph theory, we analyze the topological landscape of web service networks formed by real-world data set, either downloaded from web service repositories or crawled by a search engine. We first propose a flexible framework to study syntactic web service matchmaking in a unified manner. Under the framework, then, the data set is analyzed from diverse perspectives and granularity. By and large, the data set is shown to exhibit small world network well and power-law-like distribution to some extent. Finally, using random graph theory, we demonstrate how to accurately estimate the size of the giant component of such web service networks.

Towards semantically enhanced Web service repositories

The success of the Web services technology has brought topics as software reuse and discovery once again on the agenda of software engineers. While there are several efforts towards automating Web service discovery and composition, many developers still search for services via online Web service repositories and then combine them manually. However, from our analysis of these online repositories, it yields that, unlike traditional software libraries, they rely on little metadata to support service discovery. We believe that the major cause is the difficulty of automatically deriving metadata that would describe rapidly changing Web service collections. In this paper, we discuss the major shortcomings of state of the art Web service repositories and as a solution, we report on ongoing work and ideas on how to use techniques developed in the context of the Semantic Web (ontology learning, matching, metadata based presentation) to improve the current situation.