基于本体和会话策略的多主体交互协议描述方法

提出一种基于会话策略的多主体交互协议描述方法。交互协议中的消息用言语动作来表示,这些言语动作被描述为WS-Agreement的schema;会话策略则描述了消息传递的流程以及交互过程中的上下文信息,如参与者属性、时间阈值等等,所有这些会话策略组成了一个多主体交互协议;采用本体描述语言OWL作为会话策略的表示语言。这种方法使得主体在一个开放、动态的环境中可以灵活地选择交互协议。     

A centralized and a decentralized method to automatically derive choreography-conforming web service systems

We present a formal model to represent orchestrations and choreographies and we define several conformance semantic relations allowing to detect whether a set of orchestration models, representing some web services, leads to the overall communications described in a choreography. Given this formal model, we develop automatic methods to derive a set of web services from a given choreography, in such a way that the system consisting of these services necessarily conforms to the choreography. These methods enable the construction of conforming systems of services even in cases where projecting the choreography into each service would lead to a non-conforming system. This issue is addressed by adding some control messages that make services interact as required by the choreography. Two different derivation methods are presented. In the centralized method, a new service is responsible of managing these additional control messages. In the decentralized method, the responsibility of handling these messages is distributed among all services.     

Oblivious and fair server-aided two-party computation

We show efficient, practical (server-aided) secure two-party computation protocols ensuring privacy, correctness and fairness in the presence of malicious (Byzantine) faults. Our requirements from the server are modest. To ensure privacy and correctness, we only assume a circuit evaluation service, executing an initialisation program provided by both parties. To ensure fairness, we further assume a trusted-decryption service, providing decryption service using a known public key. Our fairness-ensuring protocol is optimistic, i.e., the decryption service is invoked only in case of faults.Both of these trusted services are feasible in practice, and may be useful for additional tasks; both can also be distributed, with linear overhead, for redundancy. We believe that the protocols are sufficiently efficient, to allow deployment, in particular for financial applications. We also propose applications which constitute natural candidates to benefit from our protocols.     

Automatic derivation of BPEL4WS from IDEF0 process models

Integration definition for function modelling (IDEF0) is one of the most popular notations for modelling business processes. It employs a rather simple and intuitive modelling construct, consisting of boxes representing functions and arrows connecting them signifying flow of information and materials. Web services on the other hand are an emerging technology for implementing distributed systems. Web service orchestration languages, such as Business Process Execution Language for Web Services (BPEL4WS), are the emerging approach for describing processes as networks of coordinated web services. Business processes as captured in IDEF0 models, however, may contain both web services as well as other types of activities which need to be coordinated. By automatically analysing the Extensible Markup Language (XML) definition of an IDEF0 model, we can identify how web services interact with other activities and at runtime generate code to support the orchestration of web services with the overall business process. The approach proposed is independent of the orchestration language and ensures an implementation independent model for specifying web service orchestrations. This approach also enables the top-down analysis of a business process to its constituent web services and avoids any misalignment problems during design time between the two.     

A smartphone watch for mobile surveillance service

Mobile surveillance service is regarded as one of the Internet applications to which much attention is recently given. However, the time and cost problem resulting from using heterogeneous platforms and proprietary protocols must be a burden to developing such systems and expanding their services. In this paper, we present a framework of mobile surveillance service for smartphone users. It includes the design and implementation of a video server and a mobile client called smartphone watch. A component-based architecture is employed for the server and client for easy extension and adaptation. We also employ the well-known standard web protocol HTTP to provide higher compatibility and portability than using a proprietary one. Three different video transmission modes are provided for efficient usage of limited bandwidth resource. We demonstrate our approach via real experiments on a commercial smartphone.     

Static consistency checking of web applications with WebDSL

Modern web application development frameworks provide web application developers with high-level abstractions to improve their productivity. However, their support for static verification of applications is limited. Inconsistencies in an application are often not detected statically, but appear as errors at run-time. The reports about these errors are often obscure and hard to trace back to the source of the inconsistency. A major part of this inadequate consistency checking can be traced back to the lack of linguistic integration of these frameworks. Parts of an application are defined with separate domain-specific languages, which are not checked for consistency with the rest of the application. Examples include regular expressions, query languages and XML-based languages for definition of user interfaces. We give an overview and analysis of typical problems arising in development with frameworks for web application development, with Ruby on Rails, Lift and Seam as representatives.To remedy these problems, in this paper, we argue that domain-specific languages should be designed from the ground up with static verification and cross-aspect consistency checking in mind, providing linguistic integration of domain-specific sub-languages. We show how this approach is applied in the design of WebDSL, a domain-specific language for web applications, by examining how its compiler detects inconsistencies not caught by web frameworks, providing accurate and clear error messages. Furthermore, we show how this consistency analysis can be expressed with a declarative rule-based approach using the Stratego transformation language.     

Supporting the semi-automatic semantic annotation of web services: A systematic literature review

ContextSemantically annotating web services is gaining more attention as an important aspect to support the automatic matchmaking and composition of web services. Therefore, the support of well-known and agreed ontologies and tools for the semantical annotation of web services is becoming a key concern to help the diffusion of semantic web services.ObjectiveThe objective of this systematic literature review is to summarize the current state-of-the-art for supporting the semantical annotation of web services by providing answers to a set of research questions.MethodThe review follows a predefined procedure that involves automatically searching well-known digital libraries. As a result, a total of 35 primary studies were identified as relevant. A manual search led to the identification of 9 additional primary studies that were not reported during the automatic search of the digital libraries. Required information was extracted from these 44 studies against the selected research questions and finally reported.ResultsOur systematic literature review identified some approaches available for semantically annotating functional and non-functional aspects of web services. However, many of the approaches are either not validated or the validation done lacks credibility.ConclusionWe believe that a substantial amount of work remains to be done to improve the current state of research in the area of supporting semantic web services.     

Quality models for web services: A systematic mapping

ContextQuality of Service (QoS) is a major issue in various web service related activities. Quality models have been proposed as the engineering artefact to provide a common framework of understanding for QoS, by defining the quality factors that apply to web service usage.ObjectiveThe goal of this study is to evaluate the current state of the art of the proposed quality models for web services, specifically: (1) which are these proposals and how are they related; (2) what are their structural characteristics; (3) what quality factors are the most and least addressed; and (4) what are their most consolidated definitions.MethodWe have conducted a systematic mapping by defining a robust protocol that combines automatic and manual searches from different sources. We used a rigorous method to elicitate the keywords from the research questions and a selection criteria to retrieve the final papers to evaluate. We have adopted the ISO/IEC 25010 standard to articulate our analysis.ResultsWe have evaluated 47 different quality models from 65 papers that fulfilled the selection criteria. By analyzing in depth these quality models, we have: (1) distributed the proposals along the time dimension and identified their relationships; (2) analyzed their size (visualizing the number of nodes and levels) and definition coverage (as indicator of quality of the proposals); (3) quantified the coverage of the different ISO/IEC 25010 quality factors by the proposals; (4) identified the quality factors that appeared in at least 30% of the surveyed proposals and provided the most consolidated definitions for them.ConclusionsWe believe that this panoramic view on the anatomy of the quality models for web services may be a good reference for prospective researchers and practitioners in the field and especially may help avoiding the definition of new proposals that do not align with current research.     

OntoPipeliner: An ontology-based automatic semantic service pipeline generator

The Web is a distributed environment rich with Web services going through continual metamorphosis; thus, sustaining semantic stability of service composition has become a major challenge. Automatic service composition – enabled both by the use of ontologies that describe service domains and by user-specified constraints bound to the ontologies – provides us candidate service pipelines at composition design time. The ontology-based languages for semantically describing web services, such as OWL-S, have been widely used. Though rich and comprehensive in their expressiveness, the use of these languages still leaves much of composition process manual. In this work, we present an ontology-based semantic web service composition system called OntoPipeliner. It employs a novel way of utilizing characteristics of Web services that reflect the classes and properties of domain ontologies and provides the ontology-guided constraints for automatic composition of services, in order to guide the user toward the best pipeline that meets the user requirements.     

CASD: Management of a context-aware service directory

Traditional web service discovery is strongly related to the use of service directories. Especially in the case of mobile web services, where both service requestors and providers are mobile, the dynamics impose the need for directory-based discovery. Context plays an eminent role with mobility, as a filtering mechanism that enhances service discovery through the selection of the most appropriate service. However, current service directory specifications do not focus on mobility of services or context-awareness. In this paper, we propose CASD, a context-aware service directory, envisioned as a context-based index for services on top of any traditional service directory, and design algorithms for construction, search, update and merge of such directories. Furthermore, we describe the architecture of our system for context-aware service discovery, we present a prototype implementation and discuss the experimental results as well as the overall evaluation. The contribution of this work is the proposal for a novel, enhanced representation model for a context-aware service directory.     

Time-constrained services: a framework for using real-time web services in industrial automation

The use of web services in industrial automation, e.g. in fully automated production processes like car manufacturing, promises simplified interaction among the manufacturing devices due to standardized protocols and increased flexibility with respect to process implementation and reengineering. Moreover, the adoption of web services as a seamless communication backbone within the overall industrial enterprise has additional benefits, such as simplified interaction with suppliers and customers (i.e. horizontal integration) and avoidance of a break in the communication paradigm within the enterprise (i.e. vertical integration). The Time-Constrained Services (TiCS) framework is a development and execution environment that empowers automation engineers to develop, deploy, publish, compose, and invoke time-constrained web services. TiCS consists of four functional layers—tool support layer, real-time infrastructural layer, real-time service layer, and hardware layer—which contain several components to meet the demands of a web service based automation infrastructure. This article gives an overview of the TiCS framework. More precisely, the general design considerations and an architectural blueprint of the TiCS framework are presented. Subsequently, selected key components of the TiCS framework are discussed in detail: the SOAP4PLC engine for equipping programmable logic controllers with a web service interface, the SOAP4IPC engine for processing web services in real-time on industrial PCs, the WS-TemporalPolicy language for describing time constraints, and the TiCS Modeler for composing time-constrained web services into a time-constrained BPEL4WS workflow.     

SemantiClean

In our research on using information extraction to help populate semantic web resources, we have encountered significant obstacles to interoperability between the technologies. We believe these obstacles to be endemic to the basic paradigms and not quirks of the specific implementations we have worked with. In particular, we identify five dimensions of interoperability that must be addressed to successfully employ information extraction systems to populate semantic web resources that are suitable for reasoning. We call the task of transforming IE data into knowledge-based resources knowledge integration and we report results of experiments in which the knowledge integration process uses the deeper semantics of OWL ontologies to improve by between 8% and 13% the precision of relation extraction from text.     

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.     

Modeling and verifying choreographed multi-agent-based web service compositions regulated by commitment protocols

The competency to compose web services from available services is one of the most crucial problems in the paradigm of service-oriented computing. Conventional software engineering approaches and even standard languages compose web services as workflow models that control the business logic required to coordinate data over participating services. Such models would not apply to the design of multi-agent based web services, which offer high-level abstractions that support autonomy, business-level compliance, and flexible dynamic changes. In this article, we model interactions among multi-agent based web services by commitment modalities in the form of contractual obligations and devote multi-agent commitment protocols to regulate such interactions and engineer services composition. We develop and fully implement an automatic verifier by enriching the MCMAS model checker with certain symbolic algorithms to verify the correctness of protocols, given properties expressed in a temporal commitment logic, suitably extended with actions. We analyze the time and space complexity of the verifier. Finally, we present the experimental results of two case studies, adopted to check the verifier’s efficiency and scalability.