39,846 research outputs found
Supporting Dynamic Service Composition at Runtime based on End-user Requirements
Network-based software application services are receiving a lot of attention in recent years, as observed in developments as Internet of Services, Software as a Service and Cloud Computing. A service-oriented computing ecosystem is being created where the end-user is having an increasingly more active role in the service creation process. However, supporting end-users in the creation process, at runtime, is a difficult undertaking. Users have different requirements and preferences towards application services, use services in different situations and expect highly abstract mechanisms in the creation process. Furthermore, there are different types of end-users: some can deliver more detailed requirements or can be provided with more advanced request interface, while others can not. To tackle these issues and provide end-users with personalised service delivery, we claim that runtime automated service composition mechanisms are required. In this paper we present the DynamiCoS framework, which aims at supporting the different phases required to provide end-users with automatic service discovery, selection and composition process. In this paper we also present the developed prototype and its evaluation
A Survey on Service Composition Middleware in Pervasive Environments
The development of pervasive computing has put the light on a challenging problem: how to dynamically compose services in heterogeneous and highly changing environments? We propose a survey that defines the service composition as a sequence of four steps: the translation, the generation, the evaluation, and finally the execution. With this powerful and simple model we describe the major service composition middleware. Then, a classification of these service composition middleware according to pervasive requirements - interoperability, discoverability, adaptability, context awareness, QoS management, security, spontaneous management, and autonomous management - is given. The classification highlights what has been done and what remains to do to develop the service composition in pervasive environments
Towards runtime discovery, selection and composition of semantic services
Service-orientation is gaining momentum in distributed software applications, mainly because it facilitates interoperability and allows application designers to abstract from underlying implementation technologies. Service composition has been acknowledged as a promising approach to create composite services that are capable of supporting service user needs, possibly by personalising the service delivery through the use of context information or user preferences. In this paper we discuss the challenges of automatic service composition, and present DynamiCoS, which is a novel framework that aims at supporting service composition on demand and at runtime for the benefit of service end-users. We define the DynamiCoS framework based on a service composition life-cycle. Framework mechanisms are introduced to tackle each of the phases and requirements of this life-cycle. Semantic services are used in our framework to enable reasoning on the service requests issued by end users, making it possible to automate service discovery, selection and composition. We validate our framework with a prototype that we have built in order to experiment with the mechanisms we have designed. The prototype was evaluated in a testing environment using some use case scenarios. The results of our evaluation give evidences of the feasibility of our approach to support runtime service composition. We also show the benefits of semantic-based frameworks for service composition, particularly for end-users who will be able to have more control on the service composition process
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Towards an aspect weaving BPEL engine
This position paper proposes the use of dynamic aspects and
the visitor design pattern to obtain a highly configurable and
extensible BPEL engine. Using these two techniques, the
core of this infrastructural software can be customised to
meet new requirements and add features such as debugging,
execution monitoring, or changing to another Web Service
selection policy. Additionally, it can easily be extended to
cope with customer-specific BPEL extensions. We propose
the use of dynamic aspects not only on the engine itself
but also on the workflow in order to tackle the problems of
Web Service hot deployment and hot fixes to long running
processes. In this way, composing aWeb Service "on-the-fly"
means weaving its choreography interface into the workflow
Handling Data-Based Concurrency in Context-Aware Service Protocols
Dependency analysis is a technique to identify and determine data
dependencies between service protocols. Protocols evolving concurrently in the
service composition need to impose an order in their execution if there exist
data dependencies. In this work, we describe a model to formalise context-aware
service protocols. We also present a composition language to handle dynamically
the concurrent execution of protocols. This language addresses data dependency
issues among several protocols concurrently executed on the same user device,
using mechanisms based on data semantic matching. Our approach aims at
assisting the user in establishing priorities between these dependencies,
avoiding the occurrence of deadlock situations. Nevertheless, this process is
error-prone, since it requires human intervention. Therefore, we also propose
verification techniques to automatically detect possible inconsistencies
specified by the user while building the data dependency set. Our approach is
supported by a prototype tool we have implemented.Comment: In Proceedings FOCLASA 2010, arXiv:1007.499
Can Component/Service-Based Systems Be Proved Correct?
Component-oriented and service-oriented approaches have gained a strong
enthusiasm in industries and academia with a particular interest for
service-oriented approaches. A component is a software entity with given
functionalities, made available by a provider, and used to build other
application within which it is integrated. The service concept and its use in
web-based application development have a huge impact on reuse practices.
Accordingly a considerable part of software architectures is influenced; these
architectures are moving towards service-oriented architectures. Therefore
applications (re)use services that are available elsewhere and many
applications interact, without knowing each other, using services available via
service servers and their published interfaces and functionalities. Industries
propose, through various consortium, languages, technologies and standards.
More academic works are also undertaken concerning semantics and formalisation
of components and service-based systems. We consider here both streams of works
in order to raise research concerns that will help in building quality
software. Are there new challenging problems with respect to service-based
software construction? Besides, what are the links and the advances compared to
distributed systems?Comment: 16 page
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