Web Service Choreography Research Articles

Towards automated choreography of Web services using planning in large scale service repositories

Automated composition of Web services is becoming a prominent paradigm for implementing and delivering distributed applications. A composed service can be described either by orchestration or choreography. Service orchestration has a centralized controller which coordinates the services in a composite service. Differently, service choreography assumes that all of the participating services collaborate with each other to achieve a globally shared task. Choreography has received great attention and demonstrated a few key advantages over orchestration such as data efficiency, distributed control, and scalability. Although there is extensive research on the languages and protocols of choreography, automated design of choreography plans, especially distributed plans for multiple roles, is more complex and not studied before. In this paper, we propose a novel planning-based approach, including compilation of contingencies, stateful actions, dependency analysis and communication control, which can automatically convert a given composition task to a distributed choreography specification. The experimental results conducted on large scale service repositories show the effectiveness and efficiency of our approach for automated choreography of Web services.

A Comprehensive Survey of Web Service Choreography, Orchestration And Workflow Building

services and composition of web services play an important role in building a workflow. This paper discusses the basics of a web service, service composition and methods used for service composition. It also discusses various proposals that were provided as solutions to the problems existing in web service composition. It also proposes future research directions that can efficiently tackle the issues of web service composition. Keywordsmining; web service orchestration; choreography; service composition; ranking and selection; semantic service selection

Toward a Better Interoperability of Enterprise Information Systems: A CPNs and Timed CPNs -based Web Service Interoperability Verification in a Choreography

Abstract Service-Oriented Architectures (SOA) claim to facilitate the construction of flexible and loosely coupled business applications. Therefore it is seen as an enabling factor for the interoperability of Enterprise Information Systems (EIS). Web services are currently the most promised concretization of SOA. This concept is currently carried further to address the composition of individual services through orchestration and choreography in order to automate a business process allowing enterprises to develop value added products. Web service choreographies are more collaborative in nature and permit direct interactions between Web services. In order to have a better interoperability of EIS, a good behavior and an efficiency of Web service choreography is necessary. This paper addresses the raised issues by providing a process of Web service choreography. The originality of this process is the formal verification of the service interoperability basing on formal methods and tools, especially Colored Petri Nets (CPNs) and Timed CPNs formal specification languages, and model checking and simulation techniques. This formal verification is done at design time, which is an important step towards reliable Web service choreography, since problems could be detected early in the development cycle before even starting the implementation. It aims to prove that Web service choreography is correct in terms on message ordering constraints and efficient in terms of time constraints. This originality reflects the reality of enterprises interoperability that depends not only on qualitative constraints (message ordering) but also on quantitative ones such as time. The effectiveness of work has been validated using the recent version of CPN Tools.

A modelling language and a tool for web services composition

Web services technology is the most common implementation of service oriented architecture. Web services are based on open technologies such as eXtensible Markup Language (XML) and offer a distributed approach for the integration of heterogeneous applications across the internet. The process of combining web services functionalities into one composite service is called web services composition. To perform this task, several languages such as Business Process Execution Language (BPEL), Web Services Flow Language (WSFL) and Web Service Choreography Interface (WSCI) have emerged. These languages are based on programming concepts and neglect the specification step which is very important in any software development process. In this paper, we address the formal specification of web services descriptions and the modelling of their composition using the model driven engineering principles. To this end, we propose a domain specific language (DSL) called S-GNet. The proposed DSL introduces new modelling elements which make it well adapted to the web services characteristics. We also propose a graph grammar which transforms Web Services Description Language (WSDL) descriptions into their equivalent S-GNet specifications. This grammar is integrated within an S-GNet modelling tool.

Corroboration Strategy for Web Services Choreography using Revise Buchi Automata

Web service choreography is a methodology for building value-added applications by aggregating several existing web services together according to business requirements. Web service choreography has been widely explored in the past and various approaches have been proposed. Only a few works have been carried out for verification of composed web services for deterministic system and no work has been carried for non-deterministic system. This paper introduces an approach for verifying the WSC using Revise Buchi Automata (RBA) for non-deterministic system. The correctness properties of the non-deterministic system have been evaluated based on sparseness and reachability problem. Primarily the web services are composed by using Web Service Choreography Description Language (WS-CDL) and then the composed service is translated into RBA. A new algorithm called Revise Buchi Sparseness Reachability (RBSR) has been developed to avoid the Sparseness problem and Reachability problem. A tool (WSCVT) has been developed using jave for verifying the RBSR algorithm. The proposed approach is verified using this tool and the results revealed better performance in terms of avoiding sparseness and reachability problems at 95% compared to the existing approaches.

Applied Research and Modeling Based on Web Service Choreography Language

In order to generate the realization model of business process quickly, a method of formalize model is proposed which based on Web service choreography language in this paper. The specific studying process is as follows. Firstly, several Web services choreography language and its characteristics are introduced, and then analyzed the natural projection and expansion model of service choreography, finally, model checker SPIN is used to simulate and verify the service choreography. The result shows that the succinct service choreography language can create Web service choreography model efficiently, and through the projection rules, which can better meet the needs of the business process implementation.

Algorithms for checking channel passing in web service choreography

Web service choreography describes global models of service interactions among a set of participants. For an interaction to be executed, the participants must know the required channel(s) used in the interaction, otherwise the execution will get stuck. Since channels are composed dynamically, the initial channel set of each participant is often insufficient to meet the requirements. It is the responsibility of the participants to pass required channels owned (known) by one to others. Since service choreography may involve many participants and complex channel constraints, it is hard for designers to specify channel passing in a choreography exactly as required. We address the problem of checking whether a service choreography lacks channels or has redundant channels, and how to automatically generate channel passing based on interaction flows of the service choreography in the case of channel absence. Concretely, we propose a simple language Chor c , a channel interaction sub-language for modeling the channel passing aspect of service choreography. Based on the formal operational semantics of Chor c , the algorithms for static checking of service choreography and generating channel passing are also studied, and the complexity results of algorithms are discussed. Moreover, some illustrated service choreography examples are presented to show how to formalize and analyze service choreography with channel passing in Chor c .

The semantics and verification of timed service choreography

As a service composition and coordination language, the service choreography gives the global and neutral view on the collaboration among a collection of highly distributed services involving multiple different organizations or heterogeneous independent processes. In this paper, we extend the service choreography by introducing the explicit time activity, which can be used to specify and reason about the timed behaviour of Web service choreography. Then we explore an execution model for the proposed timed service choreography which possesses several novel features, such as timed activity, choreography composition, exception handling and finalization. Furthermore, a set of mapping rules is elaborately designed to translate the timed choreography into communicating sequential programs processes, thus the corresponding simulation and verification of Web services choreographies with timing restrictions can be carried out in the model checker process analysis toolkit. The case study shows that our approach is both effective and practical.

Search GenBank: interactive orchestration and ad-hoc choreography of Web services in the exploration of the biomedical resources of the National Center For Biotechnology Information

BackgroundDue to the growing number of biomedical entries in data repositories of the National Center for Biotechnology Information (NCBI), it is difficult to collect, manage and process all of these entries in one place by third-party software developers without significant investment in hardware and software infrastructure, its maintenance and administration. Web services allow development of software applications that integrate in one place the functionality and processing logic of distributed software components, without integrating the components themselves and without integrating the resources to which they have access. This is achieved by appropriate orchestration or choreography of available Web services and their shared functions. After the successful application of Web services in the business sector, this technology can now be used to build composite software tools that are oriented towards biomedical data processing.ResultsWe have developed a new tool for efficient and dynamic data exploration in GenBank and other NCBI databases. A dedicated search GenBank system makes use of NCBI Web services and a package of Entrez Programming Utilities (eUtils) in order to provide extended searching capabilities in NCBI data repositories. In search GenBank users can use one of the three exploration paths: simple data searching based on the specified user’s query, advanced data searching based on the specified user’s query, and advanced data exploration with the use of macros. search GenBank orchestrates calls of particular tools available through the NCBI Web service providing requested functionality, while users interactively browse selected records in search GenBank and traverse between NCBI databases using available links. On the other hand, by building macros in the advanced data exploration mode, users create choreographies of eUtils calls, which can lead to the automatic discovery of related data in the specified databases.Conclusionssearch GenBank extends standard capabilities of the NCBI Entrez search engine in querying biomedical databases. The possibility of creating and saving macros in the search GenBank is a unique feature and has a great potential. The potential will further grow in the future with the increasing density of networks of relationships between data stored in particular databases. search GenBank is available for public use at http://sgb.biotools.pl/.

A study on the scalable flow model of web services choreography and orchestration based on dynamic workflow

The goal of choreography is to define accurately the sequence of interactions between cooperating web services and guarantee that changes of participating work flow still follow the definition of message exchange. According to the requirement of the municipal and the district petition business docking, and considering the characteristics of the dynamic workflow of petition letters processing and the interaction failure easily caused in the loose coupling environment of inter-process interaction and cooperation mismatches resulting from the participating resources autonomy, this article proposes a method of services choreography and orchestration based on the interaction protocol state machine, which controls the automatic advancement of the petition interaction protocols sequence according to the interaction rules. Ten months operation of this method in the municipal and the district petition businesses docking platform shows that it helps to shield the differences of different dynamic processes, tolerate interaction failures, and accordingly reduce the maintenance complexity.

Deciding choreography realizability

Since software systems are becoming increasingly more concurrent and distributed, modeling and analysis of interactions among their components is a crucial problem. In several application domains, message-based communication is used as the interaction mechanism, and the communication contract among the components of the system is specified semantically as a state machine. In the service-oriented computing domain such communication contracts are called "choreography" specifications. A choreography specification identifies allowable ordering of message exchanges in a distributed system. A fundamental question about a choreography specification is determining its realizability, i.e., given a choreography specification, is it possible to build a distributed system that communicates exactly as the choreography specifies? Checking realizability of choreography specifications has been an open problem for several years and it was not known if this was a decidable problem. In this paper we give necessary and sufficient conditions for realizability of choreographies. We implemented the proposed realizability check and our experiments show that it can efficiently determine the realizability of 1) web service choreographies, 2) Singularity OS channel contracts, and 3) UML collaboration (communication) diagrams.

A TVPCCS Model for Testing Web Service Choreography and Generating BPEL Code

Web services are software applications which can be used through a network (intranet or Internet) via the exchange of messages based on XML standards. They are aimed at wild reusability and are typically designed to interact with other in order to build larger applications. Web service sometimes requires combining more than one to meet our requirements. Service composition is the process of creating new services from a set of services. In this context, one of the important investigations is the choreography compatibility analysis. We mean by the choreography compatibility the capability of a set of Web services of actually interacting by exchanging messages in a proper manner. Whether a set of services are compatible depends not only on their sequences of messages but also on quantitative properties such as timed properties. In this paper, we present a framework for model checking web service choreography based on checking web service (CWB) in which the web services support synchronous or asynchronous timed communications. Particularly, in this paper we present a new modeling of Web services using temporal value passing calculus of communicating systems (TVPCCS).

Realizability of Choreographies Using Process Algebra Encodings

Service-oriented computing has emerged as a new software development paradigm that enables implementation of Web accessible software systems that are composed of distributed services which interact with each other via exchanging messages. Modeling and analysis of interactions among services is a crucial problem in this domain. Interactions among a set of services that participate in a service composition can be described from a global point of view as a choreography. Choreographies can be specified using specification languages such as Web Services Choreography Description Language (WS-CDL) and visualized using graphical formalisms such as collaboration diagrams. In this paper, we present an encoding of collaboration diagrams into the LOTOS process algebra for choreography analysis. This encoding allows us to (1) check the temporal properties of choreographies using a LOTOS verification tool set called the Construction and Analysis of Distributed Processes (CADP) toolbox, (2) check the realizability of choreographies for both synchronous communication and bounded asynchronous communication, and (3) automate the peer generation process. Realizability indicates whether peers can be generated from a given choreography specification in such a way that the interactions of the generated peers exactly match the choreography specification. If a collaboration diagram is unrealizable, our approach extends the peer generation process by adding extra communication that guarantees that the peers behave according to the choreography specification.

Toward the use of Petri nets for the formalization of OWL-S choreographies

In this paper, we present a Petri net-based approach for modeling the choreography of semantic Web services which are described following the OWL-S specification. In our approach, each control construct of the OWL-S choreography is represented through a Petri net pattern that captures formally its operational semantics. The main difference between our work and the main proposals that model the semantics of OWL-S services choreography is that, although both approaches represent the service choreography with Petri nets, our proposal is also concerned with the practical execution of the Petri nets by the client. Therefore we also represent the flow of data, the outputs transformations, the effects in the environment, in addition to the structures that control the choreography of the services in our Petri net models. The implementation of the OWL-S choreography is performed in a Petri net ontology-based engine. This is another difference with traditional approaches that only use Petri nets for the analysis of the service properties. Furthermore, the use of an underlying ontology engine for supporting both the domain models of OWL-S services and the Petri net models provides several advantages in terms of reasoning, extension, and reuse.

Generating test case specifications of web service composition using model checking

Model checking techniques have been widely used in verifying web service compositions to ensure the trustworthiness. However, little research has focused on testing web services. Based on the research of model checking techniques, we propose a model checking based approach for testing web service composition which is described by using the web services choreography description language (WS-CDL). According to worldwide web consortium (W3C) candidate recommendation, the WS-CDL specification provides a language for characterizing interactions between distinct web services using XML. Since the behaviors of web service composition are asynchronous, distributed, low-coupled and platform independent, we employ the guarded automata (GA) model for specifying the composition described in WS-CDL and using the simple promela interpreter (SPIN) model checker for detecting the collaborations of web services. Test cases can be transformed from counterexamples generated by SPIN using adequacy criteria. In this paper we apply the transition coverage criterion for generating counterexamples. To illustrate our approach, we set “E-commerce service system” as an example for demonstrating how test cases can be generated using SPIN for compositions specified in WS-CDL.

Transforming Web Services Choreographies with priorities and time constraints into prioritized-time colored Petri nets

A Web Service is a self-describing, self-contained modular application that can be published, located, and invoked over a network, such as the Internet. Web Service composition provides a way to obtain value-added services by combining different existing facilities, which are then able to support the integration of commercial applications. WS-CDL (Web Services Choreography Description Language) is a W3C candidate recommendation for the description of peer-to-peer collaborations by participants in a Web Services composition. This paper focuses on several important aspects of WS-CDL, namely, data variables, timed restrictions, as well as the priorization of collaborations. In WS-CDL there are no priorities, thus, one of our first goals is to provide a WS-CDL definition of prioritized collaborations. We also define a semantics of WS-CDL (with priorities) by means of prioritized-timed colored Petri nets.

A formal and visual modeling approach to choreography based web services composition and conformance verification

Web services have emerged as the building blocks of a service-oriented architecture that supports not only enterprise application integration (EAI) and business process management (BPM) within an organization but also B2B collaboration based on business process integration. The web services choreography approach to B2B process integration allows business partners to orchestrate their own web services privately, while conforming with an agreed specification of the common ordering conditions and constraints under which messages are exchanged among partners’ web services. In this approach, choreography conformance is an essential requirement for the successful implementation of collaborative processes. A formal approach to web services composition and conformance verification based on WS-CDL and WS-BPEL is presented. This approach involves model checking as an automated means of verifying choreography conformance. The main contributions include a precise notion of choreography conformance on which verification is based as well as support for the complementary use of visual modeling (e.g. UML) and standard WS-∗ notations in composition.

A model-driven approach to predicting dependability of WS-CDL based service composition

Web Service Choreography Description Language (WS-CDL) is a mainstream standard for the description of peer-to-peer collaborations for the participants of service composition. To predict the dependability of composite service processes specified in WS-CDL allows service designers and user to decided whether the process meets the nonfunction requirements of trustworthiness, and to choose the process with better dependability to those with identical function. Unfortunately, very limited research attention is paid to dependability of WS-CDL. In this paper, we propose a model-driven approach for dependability prediction of composite service built on WS-CDL. The main innovation of this research includes a complete translation from WS-CDL to generalized stochastic Petri nets (GSPN) and a dependability (using process-normal-completion-probability as the metric of dependability of service composition) calculation algorithm based on GSPN. We also validate the accuracy of the approach in the experimental study by showing 95% confidence intervals obtained from experimental dependability results that cover the corresponding theoretical prediction values. Copyright © 2011 John Wiley & Sons, Ltd.

Modeling and verifying business processes and choreographies through the abductive proof procedure SCIFF and its extensions

In this article we survey our recent research activity concerning the use of logic programming, and in particular of abduction, for interaction specification and verification in several domains. We outline relevant results in the areas of multi-agent systems, argumentation, web services choreographies and business processes.

Design and Generation of Web Services Choreographies with Time Constraints

In this paper we show how UML 2.0 sequence diagrams can be used for the design of Web service choreographies with time constraints and how these sequence diagrams can be extended with frames for the description of Web service choreogra- phies. We then show how the diagrams can be translated into WS-CDL documents. This translation is of interest, since non-XML experts can find it difficult to implement a composite web service by WS-CDL, i.e. XML code. Graphic models, such as UML sequence diagrams, are a popular and well-studied framework for a compact represen- tation of interoperation among participants in a distributed system and can be used as a starting document for the design of a composite Web service, from which the corresponding WS-CDL document can be derived.