1,553 research outputs found
A survey of QoS-aware web service composition techniques
Web service composition can be briefly described as the process of aggregating services with disparate functionalities into a new composite service in order to meet increasingly complex needs of users. Service composition process has been accurate on dealing with services having disparate functionalities, however, over the years the number of web services in particular that exhibit similar functionalities and varying Quality of Service (QoS) has significantly increased. As such, the problem becomes how to select appropriate web services such that the QoS of the resulting composite service is maximized or, in some cases, minimized. This constitutes an NP-hard problem as it is complicated and difficult to solve. In this paper, a discussion of concepts of web service composition and a holistic review of current service composition techniques proposed in literature is presented. Our review spans several publications in the field that can serve as a road map for future research
Semantic model-driven development of service-centric software architectures
Service-oriented architecture (SOA) is a recent architectural paradigm that has received much attention. The prevalent focus on platforms such as Web services, however, needs to be complemented by appropriate software engineering methods. We propose the model-driven development of service-centric software systems. We present in particular an investigation into the role of enriched semantic modelling for a modeldriven development framework for service-centric software systems. Ontologies as the foundations of semantic modelling and its enhancement
through architectural pattern modelling are at the core of the proposed approach. We introduce foundations and discuss the benefits and also the challenges in this context
NLSC: Unrestricted Natural Language-based Service Composition through Sentence Embeddings
Current approaches for service composition (assemblies of atomic services)
require developers to use: (a) domain-specific semantics to formalize services
that restrict the vocabulary for their descriptions, and (b) translation
mechanisms for service retrieval to convert unstructured user requests to
strongly-typed semantic representations. In our work, we argue that effort to
developing service descriptions, request translations, and matching mechanisms
could be reduced using unrestricted natural language; allowing both: (1)
end-users to intuitively express their needs using natural language, and (2)
service developers to develop services without relying on syntactic/semantic
description languages. Although there are some natural language-based service
composition approaches, they restrict service retrieval to syntactic/semantic
matching. With recent developments in Machine learning and Natural Language
Processing, we motivate the use of Sentence Embeddings by leveraging richer
semantic representations of sentences for service description, matching and
retrieval. Experimental results show that service composition development
effort may be reduced by more than 44\% while keeping a high precision/recall
when matching high-level user requests with low-level service method
invocations.Comment: This paper will appear on SCC'19 (IEEE International Conference on
Services Computing) on July 1
Distribution pattern-driven development of service architectures
Distributed systems are being constructed by composing a number of discrete components. This practice is particularly prevalent within the Web service domain in the form of service process orchestration and choreography. Often, enterprise systems are built from many existing discrete applications such as legacy applications exposed using Web service interfaces. There are a number of architectural configurations or distribution patterns, which express how a composed system is to be deployed in a distributed environment. However, the amount of code
required to realise these distribution patterns is considerable. In this paper, we propose a distribution
pattern-driven approach to service composition and architecting. We develop, based on a catalog of patterns, a UML-compliant framework, which takes existing Web service interfaces as its input and generates executable Web service compositions based on a distribution pattern chosen by the software architect
A Requirement-centric Approach to Web Service Modeling, Discovery, and Selection
Service-Oriented Computing (SOC) has gained considerable popularity for implementing Service-Based Applications (SBAs) in a flexible\ud
and effective manner. The basic idea of SOC is to understand users'\ud
requirements for SBAs first, and then discover and select relevant\ud
services (i.e., that fit closely functional requirements) and offer\ud
a high Quality of Service (QoS). Understanding users requirements\ud
is already achieved by existing requirement engineering approaches\ud
(e.g., TROPOS, KAOS, and MAP) which model SBAs in a requirement-driven\ud
manner. However, discovering and selecting relevant and high QoS\ud
services are still challenging tasks that require time and effort\ud
due to the increasing number of available Web services. In this paper,\ud
we propose a requirement-centric approach which allows: (i) modeling\ud
users requirements for SBAs with the MAP formalism and specifying\ud
required services using an Intentional Service Model (ISM); (ii)\ud
discovering services by querying the Web service search engine Service-Finder\ud
and using keywords extracted from the specifications provided by\ud
the ISM; and(iii) selecting automatically relevant and high QoS services\ud
by applying Formal Concept Analysis (FCA). We validate our approach\ud
by performing experiments on an e-books application. The experimental\ud
results show that our approach allows the selection of relevant and\ud
high QoS services with a high accuracy (the average precision is\ud
89.41%) and efficiency (the average recall is 95.43%)
An Analysis of Service Ontologies
Services are increasingly shaping the worldâs economic activity. Service provision and consumption have been profiting from advances in ICT, but the decentralization and heterogeneity of the involved service entities still pose engineering challenges. One of these challenges is to achieve semantic interoperability among these autonomous entities. Semantic web technology aims at addressing this challenge on a large scale, and has matured over the last years. This is evident from the various efforts reported in the literature in which service knowledge is represented in terms of ontologies developed either in individual research projects or in standardization bodies. This paper aims at analyzing the most relevant service ontologies available today for their suitability to cope with the service semantic interoperability challenge. We take the vision of the Internet of Services (IoS) as our motivation to identify the requirements for service ontologies. We adopt a formal approach to ontology design and evaluation in our analysis. We start by defining informal competency questions derived from a motivating scenario, and we identify relevant concepts and properties in service ontologies that match the formal ontological representation of these questions. We analyze the service ontologies with our concepts and questions, so that each ontology is positioned and evaluated according to its utility. The gaps we identify as the result of our analysis provide an indication of open challenges and future work
A graph-based framework for optimal semantic web service composition
Web services are self-described, loosely coupled software components that are network-accessible
through standardized web protocols, whose characteristics are described in XML. One of the key
promises of Web services is to provide better interoperability and to enable a faster integration
between systems. In order to generate robust service oriented architectures, automatic composition
algorithms are required in order to combine the functionality of many single services into composite
services that are able to respond to demanding user requests, even when there is no single service
capable of performing such task. Service composition consists of a combination of single services
into composite services that are executed in sequence or in a different order, imposed by a set of
control constructions that can be specified using standard languages such as OWL-s or BPEL4WS.
In the last years several papers have dealt with composition of web services. Some approaches treat
the service composition as a planning problem, where a sequence of actions lead from a initial state
to a goal state. However, most of these proposals have some drawbacks: high complexity, high
computational cost and inability to maximize the parallel execution of web services. Other
approaches consider the problem as a graph search problem, where search algorithms are applied
over a web service dependency graph in order to find a solution for a particular request. These
proposals are simpler than their counterparts and also many can exploit the parallel execution of
web services. However, most of these approaches rely on very complex dependency graphs that
have not been optimized to remove data redundancy, which may negatively affect the overall
performance and scalability of these techniques in large service registries. Therefore, it is necessary
to identify, characterize and optimize the different tasks involved in the automatic service
composition process in order to develop better strategies to efficiently obtain optimal solutions. The
main goal of this dissertation is to develop a graph-based framework for automatic service
composition that generate optimal input-output based compositions not only in terms of complexity
of the solutions, but also in terms of overall quality of service solutions. More specifically, the
objectives of this thesis are: (1) Analysis of the characteristics of services and compositions. The
aim of this objective is to characterize and identify the main steps that are part for the service
composition process. (2) Framework for automatic graph-based composition. This objective will
focus on developing a framework that enables the efficient input-output based service composition,
exploring the integration with other tasks that are part of the composition process, such as service
discovery. (3) Development of optimal algorithms for automatic service composition. This objective
focuses on the development of a set of algorithms and optimization techniques for the generation of
optimal compositions, optimizing the complexity of the solutions and the overall Quality-of-
Service. (4) Validation of the algorithms with standard datasets so they can be compared with other
proposals
- âŠ