Atomic Services Research Articles

A Dynamical Reliability Prediction Algorithm for Composite Service

Dynamic selection and dynamic binding and rebinding at runtime are new characters of composite services. The traditional static reliability prediction models are unsuitable to dynamic composite services. A new reliability predicting algorithm for composite services is proposed in this paper. Firstly, a composite service is decomposed into composition unites (executing path, composite module and atomic service) according to their constituents. Consequently, a hierarchical graph of all composite units is constructed. Lastly, a new dynamic reliability prediction algorithm is presented. Comparing with the traditional reliability model, the new dynamic reliability approach is more flexible, which does not recompute reliability for all composite units and only computes the reliability of the effected composite units. In addition, an example to show how to measure the reliability based on our algorithm is designed. The experimental results show our proposed methods can give an accurate estimation of reliability. Furthermore, a more flexible sensitivity analysis is performed to determine which service component has the most significant impact on the improvement of composite service reliability.

NGSON Service Composition Ontology

TheparadigmofNextGenerationServiceOverlayNetworks(NGSON)strives to provide a unified and standardized framework of IP-based service overlay networks, creating an ecosystem of context-aware, dynamically adaptive, and self-organizing networking capabilities, including advanced routing and forwarding schemes. Service composition, i.e. the facility to combine certain atomic services into an aggregated service is considered a vital part of NGSON. As a future directed, next generation oriented paradigm NGSON must enable an intelligent, automated service composition platform. In order to also meet the objectives of being context-aware, dynamically adaptive, and self-organizing this platform needs to know and understand the semantics of its underlying functional entities. Furthermore, to be accepted by users, enterprises and service developers existing, proven, but likewise extendable standards need to be utilized as much as possible. The W3C consortium has released OWL2 for building ontologies that serve to provide machine-understandable semantics. In order to be feasible for NGSON a service composition ontology also needs to include concepts from deontic logic, i.e. needs to be able to differentiate between omissible and permissible classes, or -in finer granularity- prohibited, obligatory and optional components when composing a service from atoms. This paper aims to underline the need for an OWL2 ontology, make suggestions on its structure and required interfaces to other network entities as e.g. Software Defined Networks and Network Virtualization Functions.

Dynamic and quantitative method of analyzing service consistency evolution based on extended hierarchical finite state automata.

This paper is concerned with the dynamic evolution analysis and quantitative measurement of primary factors that cause service inconsistency in service-oriented distributed simulation applications (SODSA). Traditional methods are mostly qualitative and empirical, and they do not consider the dynamic disturbances among factors in service's evolution behaviors such as producing, publishing, calling, and maintenance. Moreover, SODSA are rapidly evolving in terms of large-scale, reusable, compositional, pervasive, and flexible features, which presents difficulties in the usage of traditional analysis methods. To resolve these problems, a novel dynamic evolution model extended hierarchical service-finite state automata (EHS-FSA) is constructed based on finite state automata (FSA), which formally depict overall changing processes of service consistency states. And also the service consistency evolution algorithms (SCEAs) based on EHS-FSA are developed to quantitatively assess these impact factors. Experimental results show that the bad reusability (17.93% on average) is the biggest influential factor, the noncomposition of atomic services (13.12%) is the second biggest one, and the service version's confusion (1.2%) is the smallest one. Compared with previous qualitative analysis, SCEAs present good effectiveness and feasibility. This research can guide the engineers of service consistency technologies toward obtaining a higher level of consistency in SODSA.

WS-SIM: A Toolkit for Modeling and Simulation of Service Composition

Web service has been rapidly developed in recent years. Web service selection is an important issue in web service composition and lots of service selection algorithms have been presented. As lots of them select an atomic service during runtime, it is not an easy task to evaluate the quality of the composited service which composed of several atomic services. In this work we introduce WS-SIM, a simulation toolkit, to solve this problem. WS-SIM supports modeling and simulating composite services and atomic services in the real world. This system also provides many common service selection algorithms and researchers can custom their own service selection algorithm for a simulation experiment. The quality of composite services can also be generated by our system. Furthermore, to demonstrate suitability of the WS-SIM, in this paper, functionalities of our system are illustrated by a case study. This confirms the usability and the applicability of WS-SIM.

Automatic composition of WSMO based geospatial semantic web services using artificial intelligence planning

Geospatial web services are widely utilised to disseminate spatial data and processing capability over the internet. Combining geospatial web services and generating composite web services out of atomic services can provide users with a higher level of functionality. This paper presents a solution for the automatic composition of geospatial web services. The solution relies on semantic web services technology and Artificial Intelligence (AI) planning techniques to generate composite geospatial web services. Web Service Modelling Ontology (WSMO) is selected as the underlying semantic web service framework. A neoclassical planning algorithm called Graphplan is used as the AI planner. The applicability of the proposed solution for composing web services is illustrated in a case study. The result shows that the proposed approach is well suited for the automatic composition of web services. The future requirements for adaptation of the approach in real world problems are broadly described.

Geomatics-based water capacity monitoring for Quake Lake and its web service implementation

A novel geomatics-based dynamic lake or reservoir water capacity computing method is proposed for mountainous area, where the water surface curves with the slope of the topography. This water capacity monitoring framework supported by web service technology was designed and implemented for a geospatial processing service. A pixel-based method to model a three-dimensional water surface was created to monitor total capacity including the dynamic capacity. First, the upstream areas are extracted from geometrically corrected SPOT-5 satellite image. The riverbed digital elevation model was intersected with the upstream area to obtain the boundary consisting of a set of points with altitude values for the water body. Considering rationality and efficiency, an improved, pixel-based river segmentation algorithm was then developed and implemented. Taking Tangjiashan Quake Lake dammed by landslide sandstone after the Wenchuan Earthquake in China in 2008 as an example, an evaluation indicates that the improved pixel-based river segmentation algorithm has the advantages of higher computational efficiency and accuracy, useful for daily monitoring of lake or reservoir water capacity in mountainous regions. Finally, water capacity monitoring models were decomposed to atomic services, to support data sharing and service model interoperability by web service. The reusable atomic services were freely customized and combined to execute water capacity calculations for different data-sets. The web service implementation experiment demonstrated powerful interoperability and remotely processing between multiusers in this geomatics-based water capacity monitoring system, which can be implemented on interplatform. It provides a general mechanism to allow client to perform distributed geospatial processing in GeoSpatial Web Service.

Determinant of Adoption Pattern of New Product/Services in Hotel Industry in Awka, Nigeria

In light of the intense competition facing the providers of hotel services/product, some managers are constantly engaged in the creation of new products that would hopefully win consumers acceptance. However, against a backdrop of changing technology and sophisticated consumer wants, inventing a successful innovation is an uphill task. The main aim of this research was to shed some light on the adoption pattern of consumers in relation to new hotel consumer innovations. In this study, the researcher chose hotel services to represent the various innovations in the consumer hospitality market. With the use of focus group discussions, interview followed by a survey in order to get an insight of consumers with regard to their adoption behaviour, the research finds factors that influenced adoption pattern of a consumer. High degree of confidence on the part of hotel staff, staff‟s good knowledge of product/service, new addition of service/product to company portfolio, influence of age, Boss influence, occupational influence, gift influence, product/service pricing, introductory marketing communication, continuing marketing communication, time effect of marketing communication. With the crunch in the consumer hospitality industry, managers are under tremendous pressure to create new products. The consumer hospitality industry has been a wave of innovation sweeping the industry, with companies experimenting with a wide range of products from lodging to atomic services. Given the advent of new technologies and shorter product development cycles, new products are constantly being introduced.

Bloom filter-based workflow management to enable QoS guarantee in wireless sensor networks

As a popular service composition technology, workflow has been successfully used in wireless sensor networks (WSNs) to compose a set of atomic services for service-oriented WSN applications. However, in a resource-constrained WSN, the sensed data is usually inaccurate or even missing, and this affects the normal execution of atomic services and may result in the non-guaranteed workflow QoS. Because the implementation of workflows in WSNs is usually hierarchical, effective workflow management in a WSN should consider both aspects of atomic services and sensor nodes, though this has largely been overlooked in existing research. Hence, a dynamic QoS-oriented, effective and efficient hierarchical workflow management mechanism is necessary. In this paper, we propose a Bloom filter-based hierarchical workflow management model, which coordinates both the atomic service level and the node level for guaranteed workflow QoS. Through constructing the service-level counting Bloom filter (CBF) to maintain the set of normal atomic services, and constructing the node-level Bloom filter (BF) to maintain the set of attribute strings of the current working nodes, an effective and efficient QoS degradation locating can be realized. Furthermore, the corresponding adaptation mechanism for guaranteed QoS is also developed. The case study and experimental evaluations demonstrate the capability of the proposed approach in WSNs.

Optimizing customized services: efficient computation in large Service Value Networks

Many times, service innovation occurs when service consumers pose innovative requirements on service providers. The trend towards standardization, simplification and modularization in the service sector has fostered the raise of Service Value Networks where providers and consumers jointly co-create value in an innovative manner. With many different competing services available, the user experience, which is captured by the non-functional Quality-of-Service (QoS) attributes, is an important competitive factor. QoS computation for complex Web services, i.e. the aggregation of QoS factors from atomic services, is essential for an automated an optimized service selection process. However, the computational complexity has often been disregarded in the respective field of research, whereas computational efficiency is inevitable for the application in online scenarios. The threefold contribution of this paper consists of a model for describing the optimization process in Service Value Networks, an extensive elaboration on different optimization techniques that allow for a computational efficient service selection and a broad analytical and simulation-based evaluation of these techniques.

SRM: a staged reliability model for Web service

SOA (Service-oriented Architecture) is becoming the major architecture for building complex Web service systems. In SOA, the lifecycle of Web services consists of four stages: service publication, service discovery, service binding and service execution. Faults may occur in any stage and cause a failure of service. The reliability of services depends on not only the faults of the remote services itself, but also the faults that may occur in any SOA stage. Designing an effective and accurate reliability prediction model for Web services has become an important and necessary task. This study first proposes a staged reliability model for atomic services, which structures the reliability estimation based on the faults that may occur at each stage. Then, the reliability of composite services or service systems can be estimated based on this staged model. An experiment is conducted to study the influence of failures at each stage on the reliability of atomic services and a case study is designed to demonstrate the reliability of composite services using our staged model. In addition, the accuracy of our approach is investigated by comparing it against CBRM (component-based reliability model). Sensitivity analysis is also performed to identify critical service. Experimental results show that our staged model can obtain higher reliability prediction accuracy and is more suitable for Web services than traditional model.

New Framework and Mechanisms of Context-Aware Service Composition in the Future Internet

The ongoing proliferation of new services, applications, and contents is leading the Internet to an architectural crisis owing to its inability to provide efficient solutions to new requirements. Clean-slate architectures for the future Internet offer a new approach to tackle current and future challenges. This proposal introduces a novel clean-slate architecture in which the TCP/IP protocol stack is decoupled in basic functionalities, that is, atomic services (ASs). A negotiation protocol, which enables context-aware service discovery for providing adapted communications, is also specified. Then, we present how ASs can be discovered and composed according to requesters' requirements. In addition, a media service provisioning use case shows the benefits of our framework. Finally, a proof-of-concept implementation of the framework is described and analyzed. This paper describes the first clean-slate architecture aligned with the work done within the ISO/IEC Future Network working group.

A New Algorithm for Semantic Web Service Matching

Considering the existing problems in Web service such as lack of semantic information and interoperability, atomic services can not cooperate with each other and be combined into composite services. In this paper, based on extended UDDI, we present a semantic annotation framework for Web service description and composition. The novel service matching algorithm not only takes into account the height factor of ontology tree and local density factor for the impact of semantic distance, but also the degree of semantic overlap. Experimental results show that the proposed service matching algorithm improved the efficiency of Web service discovery, and thus Web service can be composed easily to form more complicated inter-related services.

An Approach to Composite QoS Parameter based Web Service Selection

In any enterprise application Quality of Service (QoS) is an important attribute for selecting a service during the service composition process. Although availability and reliability have been considered as the predominant factors for estimating reputation, two aspects are lacking in the literature. First, their use is limited to composite service level and does not count at the atomic level. Second, their combined effect is not evaluated. Hence, the methodology of estimating reputation and its use for atomic service will have compounding effect on the overall quality of the composite service. We feel, better estimation of QoS can be done with both factors considered together on the simple premise that availability tells about only the probability of that service being up/running, but doesnot tell about its failure trend. In our work we present mathematical modelling of these predominant QoS factors using Markov model and Weibull analysis. A scenario has been simulated using Colored Petri Nets (CPN) to study the behavioral aspects. The outcome of our research is two fold. First, counting on probability of a service being up/running and its failure trend, together, results in a better estimation of its behavior and helps selecting the most appropriate one. Second, this resulted in selection of a service with higher reputation but lower usage cost, as opposed to using a single factor that resulted in higher reputation with higher cost.

Process model-based atomic service discovery and composition of composite semantic web services using web ontology language for services (OWL-S)

Web Service composition has become indispensable as a single web service cannot satisfy complex functional requirements. Composition of services has received much interest to support business-to-business (B2B) or enterprise application integration. An important component of the service composition is the discovery of relevant services. In Semantic Web Services (SWS), service discovery is generally achieved by using service profile of Ontology Web Languages for Services (OWL-S). The profile of the service is a derived and concise description but not a functional part of the service. The information contained in the service profile is sufficient for atomic service discovery, but it is not sufficient for the discovery of composite semantic web services (CSWS). The purpose of this article is two-fold: first to prove that the process model is a better choice than the service profile for service discovery. Second, to facilitate the composition of inter-organisational CSWS by proposing a new composition method which uses process ontology. The proposed service composition approach uses an algorithm which performs a fine grained match at the level of atomic process rather than at the level of the entire service in a composite semantic web service. Many works carried out in this area have proposed solutions only for the composition of atomic services and this article proposes a solution for the composition of composite semantic web services.

Smart Home Service Composition Research Based on Function Decomposition Tree

To meet the increasingly requirements of users in smart home and improve Web service reusable rate, this paper introduces a service composition method based on function decomposition tree. First, this method used function decomposition tree to describe the component relationship of each service component and atomic service. Second, to realize the automation in the execution of service composition, the tree expanded on logic and timing aspect based on OWL-S. In the experiment, it describes the design of function decomposition tree and its transformation to service composition file.

QoS-aware and multi-granularity service composition

Composition of Web services can be very complex, and usually involves multiple atomic services and varieties of message exchange patterns. Worst still, with the increasing amount of available services with varying granularity and quality, selecting the best combination of services becomes very challenging. This paper addresses the issues on multi-granularity service composition with awareness of the service quality. In particular, we consider how a new service composition plan is produced, while preserving its original observable behaviors of a service that are shown to the service user, by substituting the service with another service or a set of services of finer or coarser grain. The new plan aims to have services of better quality (if the corresponding underlying services are available). To achieve this, we firstly define a behavioral signature model to capture observable behaviors of services. We then present that two service composition plans are choreography equivalent if they comply with the same behavioral signature model. We then propose a behavioral extracting algorithm to obtain the behavioral signature model from a service composition plan. We also present a method to determine choreography equivalence. Finally we briefly describe our prototype implementation that captures all these proposed algorithms.

Optimal Selection and Composition of Web Services - A Survey

Internet provides huge number of Web Services and it has become an overhead for the clients to select the appropriate web Service. Different service providers offer the same service with same functionalities, and it is crucial for the users to choose the best. Also some users may need certain service that needs to be combined with already existing atomic services – thus forming a composite service. Many researchers have worked on optimal selection and composition of web services. This paper will provide a clear perspective for the future research.

“Adore”, a logical meta-model supporting business process evolution

The Service Oriented Architecture (Soa) paradigm supports the assembly of atomic services to create applications that implement complex business processes. Since “real-life” processes can be very complex, composition mechanisms inspired by the Separation of Concerns paradigm (e.g. features, aspects) are good candidates to support the definition and the upcoming evolutions of large systems. We propose Adore, “an Activity meta-moDel supOrting oRchestration Evolution” to address this issue. The Adore meta-model allows process designers to express in the same formalism business processes and fragments of processes. Such fragments define additional activities that aim to be integrated into other processes and adequately support their evolution. The underlying logical foundations of Adore allow the definition of interference detection rules as logical predicate, as well as the definition of consistency properties on Adore models. Consequently, the Adore framework supports process designers while they design and then apply evolutions on large processes, managing the detection of interferences among fragments and ensuring that the composed processes are consistent and do not depend on the order of the composition.

Service Composition in Knowledge-based SOA Systems

In this paper, we present the solution of the problem of Service Composition in Knowledge-based SOA (Service Oriented Architecture) Systems. SOA based systems are built of services - atomic or complex ones. Each service may have a different functional and non-functional description. The methods how to retrieve atomic service and compose complex services according to the user’s needs are discussed here.

Composing web services enacted by autonomous agents through agent-centric contract net protocol

ContextAgents are considered as one of the fundamental technologies underlying open and dynamic systems that are largely enabled by the semantic web and web services. Recently, there is a trend to introduce the notion of autonomy empowered by agents into web services. However, it has been argued that the characteristics of autonomy will make agents become available intermittently and behave variedly over time, which therefore increase the complexity on devising mechanisms for composing services enacted by autonomous agents. ObjectiveIn this work, we propose an extension to Contract Net protocol, called Agent-centric Contract Net Protocol (ACNP), as a negotiation mechanism with three key features for composing web services enacted by autonomous agents. Method(1) A matchmaking mechanism embedded in a middle agent (as a service matchmaker) for discovering web services that are available intermittently is presented based on the concept of agent roles; (2) A selection algorithm based on risk-enabled reputation model (REAL) embedded in a manager agent (as a service composer) is introduced to serve a basis for selecting web services with variant performance; and (3) A negotiation mechanism between a manager agent and contractor agents (as atomic services) is devised and enables both a service composer and the atomic services to request, refuse or agree on adapting changes of services. ResultsThe problem of assembling a computer is discussed in this paper. ConclusionIt is increasingly recognised that web services would become more autonomous by introducing diverse agent technologies to better constitute more complex systems in open and dynamic environments. As web service technologies are best exploited by composite services, it is imperative to devise mechanisms for composing services of autonomy.