Service Discovery and Composition Based on Contracts and Choreographic Descriptions

2012 ◽  
pp. 60-88
Author(s):  
Mario Bravetti ◽  
Gianluigi Zavattaro
Keyword(s):  
Service Discovery ◽  
Operational Semantics ◽  
Asynchronous Communication ◽  
Synchronous Communication ◽  
Transition Systems ◽  
Service Contracts ◽  
Contract Compliance ◽  
Service Oriented ◽  
Labeled Transition System ◽  
Contract Language

The authors discuss the interplay between the notions of contract compliance, contract refinement, and choreography conformance in the context of service oriented computing, by considering both synchronous and asynchronous communication. Service contracts are specified in a language independent way by means of finite labeled transition systems. In this way, the theory is general and foundational as the authors abstract away from the syntax of contracts and simply assume that a contract language has an operational semantics defined in terms of a labeled transition system. The chapter makes a comparative analysis of synchronous and asynchronous communication. Concerning the latter, a realistic scenario is considered in which services are endowed with queues used to store the received messages. In the simpler context of synchronous communication, the authors are able to resort to the theory of fair testing to provide decidability results.

PROCESS MODEL ONTOLOGY-BASED MATCHMAKING OF SEMANTIC WEB SERVICES

2011 ◽  
Vol 20 (04) ◽  
pp. 357-370 ◽  
Author(s):  
D. PAULRAJ ◽  
S. SWAMYNATHAN ◽  
M. MADHAIYAN
Keyword(s):  
Web Services ◽  
Semantic Web ◽  
Web Service ◽  
Process Model ◽  
Service Discovery ◽  
Service Oriented Architecture ◽  
Semantic Web Services ◽  
Functional Part ◽  
Service Oriented ◽  
Concise Description

One of the key challenges of the Service Oriented Architecture is the discovery of relevant services for a given task. In Semantic Web Services, service discovery is generally achieved by using the service profile ontology of OWL-S. Profile of a service is a derived, concise description and not a functional part of the semantic web service. There is no schema present in the service profile to describe the input, output (IO), and the IOs in the service profile are not always annotated with ontology concepts, whereas the process model has such a schema to describe the IOs which are always annotated with ontology concepts. In this paper, we propose a complementary sophisticated matchmaking approach which uses the concrete process model ontology of OWL-S instead of the concise service profile ontology. Empirical analysis shows that high precision and recall can be achieved by using the process model-based service discovery.

scholarly journals The Interplay of Content and Community in Synchronous and Asynchronous Communication: Virtual Communication in a Graduate Seminar

2002 ◽  
Vol 28 (2) ◽  
Author(s):  
Richard A. Schwier ◽  
Shelly Balbar
Keyword(s):  
Sense Of Community ◽  
Asynchronous Communication ◽  
Synchronous Communication ◽  
Bulletin Board ◽  
Virtual Communication ◽  
Graduate Seminar ◽  
Different Types ◽  
Group A ◽  
The University ◽  
Intellectual Limitations

A group of graduate students and an instructor at the University of Saskatchewan experimented with the use of synchronous communication (chat) and asynchronous communication (bulletin board) in a theory course in Educational Communications and Technology for an eight-month period. Synchronous communication contributed dramatically to the continuity and convenience of the class, and promoted a strong sense of community. At the same time, it was viewed as less effective than asynchronous communication for dealing with content and issues deeply, and it introduced a number of pedagogical and intellectual limitations. We concluded that synchronous and asynchronous strategies were suitable for different types of learning, and what we experienced was a balancing act between content and community in our group. A combination of synchronous and asynchronous experiences seems to be necessary to promote the kind of engagement and depth required in a graduate seminar.

Issues on the Compatibility of Web Service Contracts

2013 ◽  
pp. 154-188 ◽  
Author(s):  
Surya Nepal ◽  
John Zic
Keyword(s):  
Web Service ◽  
Service Composition ◽  
Large Scale ◽  
Service Oriented Architecture ◽  
Distributed Applications ◽  
Compatibility Conditions ◽  
Service Contract ◽  
Service Contracts ◽  
Service Oriented ◽  
Application Developers

In the Service Oriented Architecture (SOA) model, a service is characterized by its exchange of asynchronous messages, and a service contract is a desirable composition of a variety of messages. Though this model is simple, implementing large-scale, cross-organizational distributed applications may be difficult to achieve in general, as there is no guarantee that service composition will be possible because of incompatibilities of Web service contracts. We categorize compatibility issues in Web service contracts into two broad categories: (a) between contracts of different services (which we define as a composability problem), and (b) a service contract and its implementation (which we define as a conformance problem). This chapter examines and addresses these problems, first by identifying and specifying contract compatibility conditions, and second, through the use of compatibility checking tools that enable application developers to perform checks at design time.

Event Processing in Web Service Runtime Environments

2010 ◽  
pp. 284-306 ◽  
Author(s):  
Anton Michlmayr ◽  
Philipp Leitner ◽  
Florian Rosenberg ◽  
Schahram Dustdar
Keyword(s):  
Web Service ◽  
Service Discovery ◽  
Historical Event ◽  
Event Processing ◽  
Service Oriented Architectures ◽  
Loosely Coupled ◽  
Service Invocation ◽  
Runtime Environment ◽  
Service Oriented ◽  
Runtime Environments

Service-oriented Architectures (SOA) and Web services have received a lot of attention from both industry and academia. Services as the core entities of every SOA are changing regularly based on various reasons. This poses a clear problem in distributed environments since service providers and consumers are generally loosely coupled. Using the publish/subscribe style of communication service consumers can be notified when such changes occur. In this chapter, we present an approach that leverages event processing mechanisms for Web service runtime environments based on a rich event model and different event visibilities. Our approach covers the full service lifecycle, including runtime information concerning service discovery and service invocation, as well as Quality of Service attributes. Furthermore, besides subscribing to events of interest, users can also search in historical event data. We show how this event notification support was integrated into our service runtime environment VRESCo and give some usage examples in an application context.

Distributed and Adaptive Service Discovery Using Preference

2010 ◽  
pp. 396-424
Author(s):  
Ryota Egashira ◽  
Akihiro Enomoto ◽  
Tatsuya Suda
Keyword(s):  
Service Discovery ◽  
Service Providers ◽  
End Users ◽  
Research Community ◽  
End User ◽  
Network Service ◽  
Preference Information ◽  
Extensive Simulation ◽  
Service Oriented Computing ◽  
Service Oriented

In Service-Oriented Computing, service providers publish their services by deploying service components which implement those services into a network. Since such services are distributed around the network, Service-Oriented Computing requires the functionality to discover the services that meet certain criteria specified by an end user. In order to overcome the scalability issue that the current centralized discovery mechanism inherently has, distributed discovery mechanisms that the P2P research community has developed may be promising alternatives. This chapter outlines existing distributed mechanisms and proposes a novel discovery mechanism that utilizes end users’ preferences. The proposed mechanism allows end users to return their feedback that describes the degree of the preference for discovered services. The returned preference information is stored at nodes and utilized to decide where to forward subsequent queries. The extensive simulation demonstrates that the proposed mechanism meets key requirements such as selectivity, efficiency and adaptability.

Interoperable Semantic and Syntactic Service Discovery for Ambient Computing Environments

2011 ◽  
pp. 213-232 ◽  
Author(s):  
Sonia Ben Mokhtar ◽  
Pierre-Guillaume Raverdy ◽  
Aitor Urbieta ◽  
Roberto Speicys Cardoso
Keyword(s):  
Service Discovery ◽  
Description Language ◽  
Semantic Approach ◽  
Service Oriented Architectures ◽  
Prototype Implementation ◽  
Service Oriented ◽  
Computing Environments ◽  
Efficient Matching ◽  
Ambient Computing ◽  
Resource Constrained Devices

The inherent heterogeneity of ambient computing environments and their constant evolution requires middleware platforms to manage networked components designed, developed, and deployed independently. Such management must also be efficient to cater for resource-constrained devices and highly dynamic situations due to the spontaneous appearance and disappearance of networked resources. For service discovery protocols (SDP), one of the main functions of service-oriented architectures (SOA), the efficiency of the matching of syntactic service descriptions is most often opposed to the fullness of the semantic approach. As part of the PLASTIC middleware, the authors present an interoperable discovery platform that features an efficient matching and ranking algorithm able to process service descriptions and discovery requests from both semantic and syntactic SDPs. To that end, the paper defines a generic, modular description language able to record service functional properties, potentially extended with semantic annotations. The proposed discovery platform leverages the advanced communication capabilities provided by the PLASTIC middleware to discover services in multi-network environments. An evaluation of the prototype implementation demonstrates that multi-protocols service matching supporting various levels of expressiveness can be achieved in ambient computing environments.

Service Discovery

2011 ◽  
pp. 107-127
Author(s):  
Gerhard Austaller
Keyword(s):  
Web Services ◽  
Real Time ◽  
Service Provider ◽  
Service Discovery ◽  
Business Processes ◽  
Software Component ◽  
Service Oriented Architectures ◽  
Network Connection ◽  
Service Oriented ◽  
The Moment

The chapter “Ubiquitous Services and Business Processes” discussed the benefits for real time enterprises of service oriented architectures (SOA) in terms of reusability and flexibility. Web services are one incarnation of SOA. This chapter gives a brief introduction to SOA. It discusses the attributes that define SOA, the roles of the participants in a service oriented environment. The essence of SOA is that clients use services offered by a service provider to get a task done. For the moment we simplify service to “a software component with network connection”. Services are offered with a description at wellknown “places” (also called registries, repositories), where clients choose services according to their needs. The chapter discusses several approaches to describe services and to look for them. Moreover, some well-known systems, and also current research, are discussed.

Experiences in Building Mobile E-Business Services

2009 ◽  
pp. 275-297
Author(s):  
Ivano De Furio ◽  
Giovanni Frattini ◽  
Luigi Romano
Keyword(s):  
Web Services ◽  
Service Discovery ◽  
New Technologies ◽  
Service Oriented Architecture ◽  
Building Blocks ◽  
Service Description ◽  
Semantic Approach ◽  
Business Services ◽  
Business Agility ◽  
Service Oriented

Organizations in all sectors of business and government are pursuing service-oriented architecture (SOA) initiatives in response to their need for increased business agility. This is particularly true for mobile telecommunications companies. That is why mobile telecom operators need to research new and innovative sources of revenue. Innovation is not an easy task. It requires embracing a new way of doing business, where new technologies are fundamental. SOA architecture and Web services technology are proposed by IT industry as the best solution to create a network of partnership and new services, but despite software producer claims, interoperability issues arise with service composition. Such a problem can be significantly reduced by adopting a semantic approach in service description and service discovery. Our research is focused on new methods and tools for building high personalized, virtual e-business services. A new service provisioning architecture based on Web services has been conceived, taking into account issues related to end-user mobility. The following pages deal with a proposal for creating real localized, personalized virtual environments using Web services and domain ontologies. In particular, to overcome interoperability issues that could arise from a lack of uniformity in service descriptions, we propose a way for controlling and enforcing annotation policies based on a Service Registration Authority. It allows services to be advertised according to guidelines and domain rules. Furthermore, this solution enables enhanced service/component discovery and validation, helping software engineers to build services by composing building blocks and provision/deliver a set of personalized services.

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