276 research outputs found
Semantic Web Services Provisioning
Semantic Web Services constitute an important research area, where vari ous underlying frameworks, such as WSMO and OWL-S, define Semantic Web
ontologies to describe Web services, so they can be automatically discovered,
composed, and invoked. Service discovery has been traditionally interpreted
as a functional filter in current Semantic Web Services frameworks, frequently
performed by Description Logics reasoners. However, semantic provisioning
has to be performed taking Quality-of-Service (QOS) into account, defining
user preferences that enable QOS-aware Semantic Web Service selection.
Nowadays, the research focus is actually on QOS-aware processes, so cur rent proposals are developing the field by providing QOS support to semantic
provisioning, especially in selection processes. These processes lead to opti mization problems, where the best service among a set of services has to be
selected, so Description Logics cannot be used in this context. Furthermore,
user preferences has to be semantically defined so they can be used within
selection processes.
There are several proposals that extend Semantic Web Services frameworks
allowing QOS-aware semantic provisioning. However, proposed selection
techniques are very coupled with their proposed extensions, most of them
being implemented ad hoc. Thus, there is a semantic gap between functional
descriptions (usually using WSMO or OWL-S) and user preferences, which are
specific for each proposal, using different ontologies or even non-semantic de scriptions, and depending on its corresponding ad hoc selection technique.
In this report, we give an overview of most important Semantic Web Ser vices frameworks, showing a comparison between them. Then, a thorough
analysis of state-of-the art proposals on QOS-aware semantic provisioning and
user preferences descriptions is presented, discussing about their applicabil ity, advantages, and defects. Results from this analysis motivate our research
work, which has been already materialized in two early contributions.Los servicios web semánticos constituyen un importante campo de inves tigación, en el cual distintos frameworks, como por ejemplo WSMO y OWL-S,
definen ontologías de la web semántica para describir servicios web, de for ma que estos puedan ser descubiertos, compuestos e invocados de manera
automática. El descubrimiento de servicios ha sido interpretado tradicional mente como un filtro funcional en los frameworks actuales de servicios web
semánticos, usando para ello razonadores de lógica descriptiva. Sin embargo,
las tareas de aprovisionamiento semántico deberían tener en cuenta la calidad
del servicio, definiendo para ello preferencias de usuario de manera que sea
posible realizar una selección de servicios web semánticos sensible a la cali dad.
Actualmente, el foco de la investigación está en procesos sensibles a la ca lidad, por lo que las propuestas actuales están trabajando en este campo intro duciendo el soporte adecuado a la calidad del servicio dentro del aprovisio namiento semántico, y principalmente en las tareas de selección. Estas tareas
desembocan en problemas de optimización, donde el mejor servicio de entre
un concjunto debe ser seleccionado, por lo que las lógicas descriptivas no pue den ser usadas en este contexto. Además, las preferencias de usuario deben ser
definidas semánticamente, de forma que puedan ser usadas en las tareas de
selección.
Existen bastantes propuestas que extienden los frameworks de servicios
web semánticos para habilitar el aprovisionamiento sensible a la calidad. Sin
embargo, las técnicas de selección propuestas están altamente acopladas con
dichas extensiones, donde la mayoría de ellas implementan algoritmos ad hoc.
Por tanto, existe un salto semántico entre las descripciones funcionales (nor malmente usando WSMO o OWL-S) y las preferencias de usuario, las cuales
son definidas específicamente por cada propuesta, usando ontologías distin tas o incluso descripciones no semánticas que dependen de la correspondiente
técnica de selección ad hoc
Towards a Unifying View of QoS-Enhanced Web Service Description and Discovery Approaches
The number of web services increased vastly in the last years. Various
providers offer web services with the same functionality, so for web service
consumers it is getting more complicated to select the web service, which best
fits their requirements. That is why a lot of the research efforts point to
discover semantic means for describing web services taking into account not
only functional characteristics of services, but also the quality of service
(QoS) properties such as availability, reliability, response time, trust, etc.
This motivated us to research current approaches presenting complete solutions
for QoS enabled web service description, publication and discovery. In this
paper we present comparative analysis of these approaches according to their
common principals. Based on such analysis we extract the essential aspects from
them and propose a pattern for the development of QoS-aware service-oriented
architectures
On User Preferences and Utility Functions in Selection: A Semantic Approach
Discovery tasks in the context of Semantic Web Services are
generally performed using Description Logics. However, this formalism
is not suited when non-functional, numerical parameters are involved
in the discovery process. Furthermore, in selection tasks, where an optimization
algorithm is needed, DLs are not capable of computing the
optimum. Although there are DLs extensions that can handle numerical
parameters, they bring decidability problems. Other solutions, as hybrid
approaches which use DLs in functional discovery and other formalisms
in non-functional selection, do not provide a semantic framework to describe
user preferences based on non-functional properties. In this work,
we propose to semantically describe user preferences, so they can be used
to perform selection within a hybrid solution. By using semantically described
utility functions in order to define user preferences, our proposal
enables interoperability between service offers and demands, while providing
a high level of expressiveness in these preferences and including
them within SWS descriptions.Comisión Interministerial de Ciencia y Tecnología TIN2006-0047
QoS-Aware Middleware for Web Services Composition
The paradigmatic shift from a Web of manual interactions to a Web of programmatic interactions driven by Web services is creating unprecedented opportunities for the formation of online Business-to-Business (B2B) collaborations. In particular, the creation of value-added services by composition of existing ones is gaining a significant momentum. Since many available Web services provide overlapping or identical functionality, albeit with different Quality of Service (QoS), a choice needs to be made to determine which services are to participate in a given composite service. This paper presents a middleware platform which addresses the issue of selecting Web services for the purpose of their composition in a way that maximizes user satisfaction expressed as utility functions over QoS attributes, while satisfying the constraints set by the user and by the structure of the composite service. Two selection approaches are described and compared: one based on local (task-level) selection of services and the other based on global allocation of tasks to services using integer programming
Semantic Web: An Integrated Approach for Web Service Discovery, Selection and Composition
Web services are remote methods can be invoked through open standards such as Simple Object Access Protocols. The increasing web services in the repositories makes the selection process very complex. The same can be extended in forming the composition of web services. This research focuses on the semantic web service selection and composition through design and implementation of a framework. The proposed framework is an ontology based service selection approach and the selected services are participating in the composition process. This approach deals with semantic search, which uses Quality of services for service selection and composition. The entire framework is implemented with semantic web technology and the performance of the system is observed with domain specific ontologies
Usages of Semantic Web Services Technologies in IoT Ecosystems and its Impact in Services Delivery: A survey
Internet of things (IoT) has begun to emerge in our daily life through the huge number of smart services provided by the devices that deploy around us. Vague and uncertainty in attributes that using in describing services, different levels of quality of each service and the limitation in capabilities of IoT devices are affect and hinder the process of discovering or selecting services. The services in IoT need to be well described to enable users to receive their services that relevant to their query. This survey will investigate the most popular semantic services models and explore the use of these models in enhancing services discovery and services selection in IoT domain. Furthermore, the survey will investigate the evaluation metrics used by each study and compare the results that they obtained. 
An Hybrid, Qos-Aware Discovery of Semantic Web Services Using Constraint Programming
Most Semantic Web Services discovery approaches are not
well suited when using complex relational, arithmetic and logical expressions,
because they are usually based on Description Logics. Moreover,
these kind of expressions usually appear when discovery is performed including
Quality-of-Service conditions. In this work, we present an hybrid
discovery process for Semantic Web Services that takes care of QoS conditions.
Our approach splits discovery into stages, using different engines
in each one, depending on its search nature. This architecture is extensible
and loosely coupled, allowing the addition of discovery engines at
will. In order to perform QoS-aware discovery, we propose a stage that
uses Constraint Programming, that allows to use complex QoS conditions
within discovery queries. Furthermore, it is possible to obtain the
optimal offer that fulfills a given demand using this approach.Comisión Interministerial de Ciencia y Tecnología TIN2006-0047
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
Non-functional Property based service selection: A survey and classification of approaches
In recent years there has been much effort dedicated to developing approaches for service selection based on non-functional properties. It is clear that much progress has been made, and by considering the individual approaches there is some overlap in functionality, but obviously also some divergence. In this paper we contribute a classification of approaches, that is, we define a number of criteria which allow to differentiate approaches. We use this classification to provide a comparison of existing approaches and in that sense provide a survey of the state of the art of the field. Finally we make some suggestions as to where the research in this area might be heading and which new challenges need to be addressed
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