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Most service composition approaches rely on top-down decomposition of a problem and AI-style planning to assemble service components into a meaningful whole, impeding reuse and flexibility. In this article, we propose an approach that starts from declarative knowledge about the semantics of individual service components and algorithmically constructs a full-blown service orchestration process that supports sequence, choice, and parallelism. The output of our algorithm can be mapped directly into a number of service orchestration languages such as OWL-S and BPEL. The approach consists of two steps. First, semantic links specifying data dependencies among the services are derived and organized in a flexible network. Second, based on a user request indicating the desired outcomes from the composition, an executable composition is constructed from the network that satisfies the dependencies. The approach is unique in producing complex compositions out of semantic links between services in a flexible way. It also allows reusing knowledge about semantic dependencies in the network to generate new compositions through new requests and modification of services at runtime. The approach has been implemented in a prototype that outperforms related composition prototypes in experiments.

Ranking and optimization of web service compositions represent challenging areas of research with significant implications for the realization of the “Web of Services” vision. “Semantic web services” use formal semantic descriptions of web service functionality and interface to enable automated reasoning over web service compositions. To judge the quality of the overall composition, for example, we can start by calculating the semantic similarities between outputs and inputs of connected constituent services, and aggregate these values into a measure of semantic quality for the composition. This paper takes a specific interest in combining semantic and nonfunctional criteria such as quality of service (QoS) to evaluate quality in web services composition. It proposes a novel and extensible model balancing the new dimension of semantic quality (as a functional quality metric) with a QoS metric, and using them together as ranking and optimization criteria. It also demonstrates the utility of Genetic Algorithms to allow optimization within the context of a large number of services foreseen by the “Web of Services” vision. We test the performance of the overall approach using a set of simulation experiments, and discuss its advantages and weaknesses.

Web service composition enhanced by semantic technologies is currently one of the most hyped and addressed issues in Service Oriented Computing. This work focuses on both i) conditional composition, i.e., how to automate the composition of services that produces non-deterministic outcomes, and ii) consistent connections between web services (also known as data flows) in the composition. To this end, we suggest the joint use of semantic links and causal laws, respectively, in the area of Description Logics and AI planning. In more detail, an augmented and adapted version of the logic programming language Golog, i.e., sslGolog, is presented as a natural formalism not only for reasoning about the latter semantic links and causal laws, but also for automatically composing non-deterministic services. sslGolog operates as an offline interpreter that supports not only binary but also n-ary sensing services (i.e., services conditioned on their possible output parameters) to achieve conditional compositions of services. Lastly, sslGolog has been implemented and tested in the context of Telecommunication scenarios.

Most of the work on automated web service composition has focused so far on composition of stateful web services. This level of composition so-called "Process Level" considers web services with their internal and complex behaviors. At process level formal models such as State Transition Systems (STS from now) or Interface Automata are the most appropriate models to represent the internal behavior of stateful web services. However such models focus only on semantics of their behaviors and unfortunately not on semantics of actions and their parameters. In this paper, we suggest to extend the STS model, by following the WSMO based annotation for Abstract State Machine. This semantic enhancement of STS so called S2 TS will enable to model semantics of internal behaviors and semantics of their actions together with their input and output parameters. Secondly, we will focus on automated generation of data flow (or the process to perform automated assignments between parameter of services involved in a composition). Thus we do not restrict to assignments of exact parameters (which is practically never used in industrial scenario) but extend assignments to semantically close parameters (e.g., through a subsumption matching) in the same ontology. Our system is implemented and interacting with web services dedicated to Telecommunication scenarios. The preliminary evaluation results showed high efficiency and effectiveness of the proposed approach.

International audience; Automated composition of Web services or the process of forming new value-added Web services is one of the most promising challenges facing the Semantic Web today. Semantics enables Web service to describe capabilities together with their processes, hence one of the key elements for the automated composition of Web services. In this paper, we focus on the functional level of Web services i.e. services are described according to some input, output parameters semantically enhanced by concepts in a domain ontology. Web service composition is then viewed as a composition of semantic links wherein the latter links refer to semantic matchmaking between Web service parameters (i.e. outputs and inputs) in order to model their connection and interaction. The key idea is that the matchmaking enables, at run time, finding semantic compatibilities among independently defined Web service descriptions. By considering such a level of composition, a formal model to perform the automated composition of Web services i.e. Semantic Link Matrix, is introduced. The latter model is required as a starting point to apply problem-solving techniques such as regression (or progression)-based search for Web service composition. The model supports a semantic context in order to find correct, complete, consistent and robust plans as solutions. In this paper, an innovative and formal model for an AI (Artificial Intelligence) planning-oriented composition is presented. Our system is implemented and interacting with Web services which are dedicated to Telecom scenarios. The preliminary evaluation results showed high efficiency and effectiveness of the proposed approach. Read More: http://www.worldscientific.com/doi/abs/10.1142/S0218843009001975

Les avancees recentes des technologies « NTIC » (Nouvelles Technologies de l’Information et des Telecommunications) ont (re)-ouvert la voie a de nouvelles solutions pour le developpement d’architectures de traitement distribue dont l’impact industriel et commercial semble cette fois tres prometteur. En effet, la conjonction de la maturite des architectures logicielles a composants distribues, la tres forte penetration des technologies du Web et enfin la forte pression de l’economie mondiale ont conduit a une irresistible proliferation de composants physiques ou logiciels autonomes disponibles et distribues sur le web. Le W3C les definit comme des « services web » : « le service web est un systeme logiciel concu pour rendre interoperable la communication de Machine a Machine connectees en reseaux. Il est decrit par une interface (WSDL) et peut interagir avec d’autres systemes par l’envoi de messages (SOAP) typiquement vehicules par un protocole HTTP et une representation syntaxique XML conjointement a d’autres standards du Web ». Une tres importante fonctionnalite de ces systemes a base de services web est leur capacite a offrir des services composites construits a partir de ces composants physiques ou logiciels autonomes et reutilisables, formant une nouvelle infrastructure de traitement informatique distribue sur le Web. Profitant de l’infrastructure du web semantique, les services web dits « semantiques » ouvrent des perspectives d’avancees cles dans le traitement d’information couvrant un large spectre d’applications comme les services commerciaux (e-Enterprise, e-Business), la recherche scientifique (ex. grille de calcul « e-Science »), l’education (e-Learning) et enfin les services aux citoyens (e-Government, e-Democracy). Nous presentons dans ce tutoriel (en deux parties) un etat de l’art synthetique des langages et technologies associes aux services web semantiques, un panorama detaille des raisonnements de decouverte existants et des solutions majeures pour la composition de services web, pour terminer sur des exemples d’applications et une feuille de route.

Recent advances in networks, information and computation grids, and WWW have resulted in the proliferation of a multitude of physically distributed and autonomously developed Web services. This second part presents two key scenarios in B2B and B2C, the central function of services composition and orchestration, the languages and prominent technologies and lastly an industry and research roadmap.

Scalable means for the search of relevant web services are essential for the development of intelligent service-based applications in the future Internet. Key idea of semantic web services is to enable such applications to perform a high-precision search and automated composition of services based on formal ontology-based representations of service semantics. In this paper, we briefly survey the state of the art of semantic web service search.

Automation of service composition is one of the most interesting challenges facing the Semantic Web and the Web of services today. Despite approaches which are able to infer a partial order of services, its data flow remains implicit and difficult to be automatically generated. Enhanced with formal representations, the semantic links between output and input parameters of services can be then exploited to infer their data flow. This work addresses the problem of effectively inferring data flow between services based on their representations. To this end, we introduce the non standard Description Logic reasoning join, aiming to provide a "constructive evidence" of why services can be connected and how non trivial links (many to many parameters) can be inferred in data flow. The preliminary evaluation provides evidence in favor of our approach regarding the completeness of data flow.

Most of existing approaches consider composition optimization as a back-end process and rarely expect non-technical end-users to interact directly with the optimization process. Thus these approaches do not enable the end-user to leverage the effects of direct interaction of the process of composition. Indeed, corrective actions can be taken only before and after the execution, not during composition construction. We focus on end-user support and optimized service selection during composition modeling. Of particular interest hereby is whether business users with limited IT skills can leverage our approach to optimize and consume web services and their composition.

Traditional service composition approaches are top-down(using domain knowledge to break-down the desired functionality), or bottom-up (using planning techniques). The former rely on available problem decomposition knowledge, whilst the latter rely on the availability of a known set of services, otherwise automatic composition has been considered impossible. We address this by proposing a third approach: Cooperative Service Composition (CSC),inspired by the way organisations come together in consortia to deliver services. CSC considers each service provider as proactive in service composition, and provides a semantics-based mechanism allowing innovative service compositions to emerge as result of providers' interactions. The key challenges we resolve are how to determine if a contribution brings the composition closer to its goal, and how to limit the number of possible solutions. In this paper we describe the approach and the solutions to the two key challenges, and demonstrate their application to the composition of financial web services.

Nowadays web users have clearly expressed their wishes to receive and interact with personalized services directly. However, existing approaches, largely syntactic content-based, fail to provide robust, accurate and useful personalized services to its users. Towards such an issue, the semantic web provides technologies to annotate and match services' descriptions with users' features, interests and preferences, thus allowing for more efficient access to services and more generally information. The aim of our work, part of service personalization, is on automated instantiation of services which is crucial for advanced usability i.e., how to prepare and present services ready to be executed while limiting useless interactions with users? To this end, we exploit Description Logics reasoning through semantic matching to (i) identify useful parts of a user profile that satisfy services requirements (i.e., input parameters) and (ii) compute the description required by a service to be executed but not provided by the user profile. Our approach, part of the EC-funded project SOA4All, was evaluated on its applicability in real world scenarios with end-users.

The current proliferation of software services means users should be supported when selecting one service out of the many which meet consumer's needs. Recommender Systems provide such support for selecting products, yet their direct application to software services is not straightforward. In this paper, we derive three requirements for software service recommender systems and then propose a hybrid recommendation approach to address these requirements and provide effective recommendations in conditions of scarce user feedback. The approach combines semantic Content-based reasoning and context-dependent Collaborative Filtering. The paper ends with the experiments based on a realistic set of semantic services against existing approaches, demonstrating how our approach can produce effective recommendation using semantic reasoning over service specifications.

Automation of web service composition is one of the most interesting challenges facing the semantic web today. Despite approaches which are able to infer partial order on services, data flow (i.e., the way data is exchanged among services) remains implicit and difficult to be inferred and automatically generated. Since web services have been enhanced with formal semantic descriptions, it becomes conceivable to exploit and reason on their semantic links (i.e., semantic matching between their functional output and input parameters) to infer data flow. Our approach has been directed to meet the main challenges facing the latter problem i.e., how to effectively i) guarantee whether a data flow is well-formed and ii) infer data flow between services based on their Description Logics (DL) descriptions. To this end, we apply constructive DL reasoning abduction, contraction and introduce the non standard DL reasoning join to model and infer data flow in compositions. The preliminary evaluation results showed high efficiency and effectiveness of the proposed approach.

Nowadays web users have clearly expressed their wishes to receive and interact with personalized services directly. However, existing approaches, largely syntactic content-based, fail to provide robust, accurate and useful personalized services to its users. Towards such an issue, the semantic web provides technologies to annotate and match services' descriptions with users' features, interests and preferences, thus allowing for more efficient access to services and more generally information. The aim of our work, part of service personalization, is on automated instantiation of services which is crucial for advanced usability i.e., how to prepare and present services ready to be executed while limiting useless interactions with users? To this end, we exploit Description Logics reasoning through semantic matching to (i) identify useful parts of a user profile that satisfy services requirements (i.e., input parameters) and (ii) compute the description required by a service to be executed but not provided by the user profile. Our approach, part of the EC-funded project SOA4All, was evaluated on its applicability in real world scenarios with end-users.

Automated web service composition has been tackled from different directions and to different purposes. In addition, most of the approaches address the composition problem with under specified requirements, returning compositions models that do not necessarily satisfy and fulfill end-users objectives. Satisfying the latter objectives is a difficult problem, especially from scratch, which requires stronger requirements and a further step of integration with service-based components in order to make service oriented computing and service composition a reality. In this work, we address this issue by presenting an innovative and integrated approach to service composition which consists of i) an automatic template process generator, that is able to generate abstract process templates and their hierarchy from past executions; ii) a novel and scalable approach to AI parametric-design techniques using a multi agent approach to configure and adapt services processes, heavily relying on the latter set of abstract process templates; iii) an optimization process that maximizes the overall quality of final compositions. Finally, we compare the scalability of these components with some experiments.

Involving people who do not have programming background in assembling and tailoring service-based applications promises to open up access to the creativity of millions of users. An increasing number of development environments aim to do this by offering drag-and-drop visual representations connecting different service components into an assembly. In contrast to the majority of these, we did not start with the technology but with the users - service producers and consumers, and studied the core issues which should be resolved before people who are not programmers can start to assemble services into meaningful applications, over and above the presentation-level integration offered by current mash-up environments. The result is an assisted approach to service composition for end users, which uses semantic technologies to shield users from the irrelevant complexity of service technology and from the need to manually resolve dependencies between services. The approach was evaluated by a focus group of non-technical users, who ranked it highly and provided valuable suggestions for further improvements and supporting features.

International audience; The proliferation of web services has led to an increased number of approaches aiming to support service composition, reusing services within larger assemblies. Looking at composition fragments is one way to facilitate composition and reuse, known as macro-level composition. In this work, we focus on the discovery and selection of such fragments to achieve a given composition goal. Our approach aims at discovering fragments using their semantic descriptions based on Description Logic. The discovery is performed by applying different levels of semantic matchmaking between fragments and goals descriptions. A Multi-Agent-System is introduced on top of the discovery process to select the most relevant fragments using three types of criteria: (i) non functional criteria such as execution price (described by service providers), (ii) cohesion criteria related to the overlap between fragments, which is inferred from the fragmentation technique, and also (iii) the goodness of semantic fit between fragments and goals. The selection process is based on an agent negotiation where each agent is responsible for a semantically coherent list of fragments. Finally, we present an approach which minimizes the number of fragments relevant for the composition goal by both (i) minimizing their overlap and (ii) maximizing the number of goals they could achieve.

Semantic web service compositions must be aligned with requirements from the target users in terms of quality requirements. Given a set of quality requirements, one can choose to either find the optimal composition or a “good enough” composition, which satisfies these requirements. Since optimizing compositions of semantic services under quality constraints is known to be NP-hard, it is unsuitable for realistic problems within large search spaces. The authors address the issue by using the “good enough” approach, selecting the first composition that passes their quality threshold. Firstly, this paper defines quality constraints within an innovative and extensible model designed to balance semantic fit (or functional quality) with quality of service (QoS) metrics. The semantic fit criterion evaluates the quality of semantic links between the semantic descriptions of Web services parameters, while QoS focuses on non-functional criteria of services. User quality requirements are met by selecting a valid composition. To allow the use of this model with a large number of candidate services as foreseen by the strategic EC-funded project SOA4All the authors formulate the selection problem as a Constraint Satisfaction Problem and test the use of a stochastic search method.

Optimizating semantic web service compositions is known to be NP-hard, so most approaches restrict the number of services and offer poor scalability. We address the scalability issue by selecting compositions which satisfy a set of constraints rather than attempting to produce an optimal composition. Firstly, we define constraints within an innovative and extensible quality model designed to balance semantic fit (or functional quality) with quality of service (QoS) metrics. The semantic fit criterion evaluates the quality of semantic links between the semantic description of Web services parameters, whilst QoS focuses on non-functional criteria of services. Coupling these criteria allows us to further constrain and select valid compositions. To allow the use of this model in the context of millions of services as foreseen by the strategic EC-funded project SOA4All, we i) formulate the selection problem as a Constraint Satisfaction Problem and ii) test the use of a stochastic search method. Finally we compare the latter with state-of-the-art approaches.

Ranking and optimization of web service compositions are some of the most interesting challenges at present. Since web services can be enhanced with formal semantic descriptions, forming the "semantic web services", it becomes conceivable to exploit the quality of semantic links between services (of any composition) as one of the optimization criteria. For this we propose to use the semantic similarities between output and input parameters of web services. Coupling this with other criteria such as quality of service (QoS) allow us to rank and optimize compositions achieving the same goal. Here we suggest an innovative and extensible optimization model designed to balance semantic fit (or functional quality) with non-functional QoS metrics. To allow the use of this model in the context of a large number of services as foreseen by the strategic EC-funded project SOA4All we propose and test the use of Genetic Algorithms.

Most of the work on automated Web service composition has focused so far on composition of stateful Web services. This level of composition so called “Process Level” considers Web services with their internal and complex behaviours. At process level formal models such as State Transition Systems (STS from now) or Interface Automata are the most appropriate models to represent the internal behaviour of stateful Web services. However such models focus only on semantics of their behaviours and unfortunately not on semantics of actions and their parameters. In this paper, we suggest to extending the STS model in the latter direction w.r.t the semantic Web. This semantic enhancement of STS so called S2TS will enable to model semantics of internal behaviours and semantics of their actions together with their input and output parameters. Secondly, we will focus on automated generation of data flow (or the process to perform automated assignments between services of a composition). Thus we do not restrict to assignments of exact parameters (which is practically never used in industrial scenario) but extend assignments to semantically close parameters (e.g., through a subsumption matching). Our system is implemented and interacting with Web services dedicated on Telecom scenarios. The preliminary evaluation results showed high efficiency and effectiveness of the proposed approach.

Automating Web service composition is a challenging area of Service Oriented Computing, requiring progress on a number of issues concerning the automation of control flow, the alignment of data flow, verification, execution monitoring, etc. In this paper, we focus on aligning data flow in semantic web service composition to ensure the robustness when executing the composed service by preventing any cases when the wrong type of data is passed on from one service to the next. The proposed solution is unique in that it ensures the robustness of data flow when automatically composing web services through the use of agent-based negotiation between web service providers. Starting from the semantic specification of a non-robust composition, we adapt the mechanism of Concept Abduction to compute the set of additional semantic descriptions necessary to ensure robustness of the semantic connections within the composed service. An agent-based negotiation is then used to solicit the additional semantic definitions which are required for achieving robust web service compositions.

International audience; Automation of Web service composition is one of the most interesting challenges facing the Service Oriented Computing today. From this challenge, many issues such as control flow, data flow, verification, execution monitoring, or recovery actions (e.g., compensation) follows. In this paper we focus on automated data flow in Web service composition. The semantic Web, as an evolving extension of the current Web, seems a key initiative to overcome the latter issue. However, even if some approaches focus on discovering potential semantic connections between Web services, few or none of these tackle implementations issues related to XML messages management at syntactic level. In this direction we present an approach for performing automated data flow in Web service composition by i) exploiting semantic matchmaking between Web service parameters (i.e., outputs and inputs) to enable their connection and interaction, and ii) adapting XML database solutions, specifically XML Schema mapping, to perform syntactic data transformation and integration of exchanged messages. Our system is implemented and interacting with Web services dedicated on a Telecom scenario. The preliminary evaluation results showed not only high efficiency and effectiveness of the proposed approach but also complementarity of the semantic matchmaking and syntactic mapping to achieving data flow in Web service composition.

Most of the work on automated semantic Web service composition has focused so far on two main levels of composition i.e., functional level and process level composition (respectively FLC and PLC from now). The former level of composition considered Web services as atomic components that can be executed in a single request-response step whereas the latter level studies in more details the protocol and the behavioural features of Web services. Since PLC i.e., a time and particularly space consuming level of composition makes difficult the scalability of composition-based applications, it seems interesting to restrict the composition of stateful but (only) independent Web services. Such a restriction make possible the composition of a large number of Web services in industrial scenarios, the whole with convincing results. In this paper we suggest to study the advantages to apply FLC together with β-composition in order to perform an automated end to end composition of stateful and independent services. In particular we focus on computational complexity results concerning the two models of composition i.e., the well-known PLC vs. the newest FLC+β-composition. Moreover we prove that FLC is an interesting and necessary level of composition to significantly reduce computational complexity not only in space but also in time.

We claim that a key feature for correct and effective web service composition, and one that has largely been ignored,is the joint consideration of (semantic) causal links and causal laws, respectively in area of description logics (DL) and AI planning. In this paper we propose a means of specifying both causal links and laws into Web service composition by integrating DL reasoning and situation calculus. To this end an augmented and adapted version of the logic programming language Golog i.e., sclGolog is presented as a natural formalism not only for reasoning about the latter links and laws, but also for automatically composing services. sclGolog operates as an offline interpreter that supports n-ary sensing actions to retrieve conditional compositions of services. Lastly sclGolog has been implemented and tested in the context of telecommunication scenarios.

Web services are conveniently advertised and published based on (stateless) functional descriptions, while they are usually realized as (stateful) processes. Therefore, the automated enactment of complex Web services on the basis of pre-existing ones requires the ability to handle services described at very different abstraction levels. This is the main reason behind the current lack of approaches capable to perform automated end-to-end composition, starting from semantic requirements to obtain executable orchestrations of stateful processes. In this paper we achieve such a challenging goal, by modularly integrating a range of incrementally more complex techniques that cover the necessary discovery and composition phases. By gradually bridging the gap between the high-level requirements and the concrete realization of services, our architecture manages sensibly the complexity of the problem: incrementally more complex techniques are provided with incrementally more focused input. The tests of our architecture on a deployed scenario witness the functionality of the platform and its integrability with standard service engines.

The semantic web promises to bring automation to the areas of web service selection, discovery, composition, invocation. In this paper we introduce a means of facilitating automation of web service composition by exploiting semantic matchmaking between web service parameters (i.e., outputs and inputs) to enable their connections and interactions. The idea is that matchmaking functions are key components to find semantic compatibilities among independently web service descriptions. To this end, our approach extends existing methods (exact, plug-in, subsume, intersection and fail) with concept abduction to provide explanations of misconnections between web services. From this we generate web service compositions that realize the goal, discovering and satisfying semantic connections between Web services. Moreover a process of relaxing the hard constraints is introduced in case the composition process failed. Our system is implemented and interacting with web services dedicated on a France Telecom scenario.

Automated composition of Web services or the process of forming new value added Web services is one of the most promising challenges in the semantic Web service research area. Semantics is one of the key elements for the automated composition of Web services because such a process requires rich machine-understandable descriptions of services that can be shared. Semantics enables Web service to describe their capabilities and processes, nevertheless there is still some work to be done. Indeed Web services described at functional level need a formal context to perform the automated composition of Web services. The suggested model (i.e., Causal link matrix) is a necessary starting point to apply problem-solving techniques such as regression-based search for Web service composition. The model supports a semantic context in order to find a correct, complete, consistent and optimal plan as a solution. In this paper an innovative and formal model for an AI planning-oriented composition is presented.

Automation of Web service composition i.e., the process of forming new value added Web services is one of the most promising challenges in Web service research area. Such an automation does not involve only a richer semantic for Web service description but also reasoning processes about those descriptions. Semantics is supposed to be one of the key elements for the automation of Web service composition. Indeed semantic Web services enable a rich machine-understandable descriptions of their capabilities and processes in order to ease automation of processes such as discovery, selection and composition. In this paper one studies the functional level description of Web services and its impact on Web service composition hence the presentation of a formal model CLM (causal link matrix). The model supports a semantic context in order to find a correct, complete and consistent plan as an AI planning-based composition. The innovative and formal model follows a forward chaining-oriented composition. Moreover two methods of optimization (i.e., local-oriented and a global-oriented) of Web service composition are introduced to discover the best plan according to a semantic criterion i.e., the causal link between Web services

The automated composition of Web services is one of the most promising ideas and at the same time one of the most challenging research area for the taking off of service-oriented applications. It is widely recognised that one of the key elements for the automated composition of Web services is semantics, i.e. unambiguous descriptions of Web services capabilities and processes. However Web services described at capability level need a formal context to perform the automated composition of Web services. In this paper a TLB architecture (three levels based architecture) is presented to perform Web service composition. Moreover we introduce the composition process as a matchmaking of domains and solve the latter problem according to a formal model, i.e. the xCLM (eXtended causal link matrix) and a knowledge base of the domain

Evolution in the telecommunications sector has led to companies within it providing APIs for their products and services, allowing others to build communication services into their own service offerings. In order to support mass adoption of this new approach, consumers of these APIs (many of which are RESTful) must be supported by a reduction in the complexity involved with describing, finding, composing and invoking them. Existing efforts to provide automation have, in general, focused on WSDL services rather than REST services. The paper explores the approach of the SOA4All project in supporting interaction with REST services which is being applied in a telecommunications focused case study.