QOS Probing Of Real-World Web Services (original) (raw)

Quality of Service (Qos) Issues in Web Services

The World Wide Web has evolved from being a pure information repository to a more functional and service oriented platform using technologies such as Web Services. Web service has been widely employed in e-business, e-government, automotive systems, multimedia services, process control, finance, and a lot of other domains. Quality-of-Service (QoS) is usually employed for describing the non-functional characteristics of Web services and employed as an important differentiating point of different Web services. With the prevalence of Web services on the Internet, a thorough awareness of the Web service QoS is becoming more and more important. In this article, an overall description of Web Services QoS requirements is presented.

A Framework for Evaluating the QoS and Cost of Web Services Based on Its Functional Performance

2016

In this corporate world, the technology of Web services has grown rapidly and its significance for the development of web based applications gradually rises over time. The success of Business to Business integration rely on finding novel partners and their services in a global business environment. However, the selection of the most suitable Web service from the list of services with the identical functionality is more vital. The satisfaction level of the customer and the provider’s reputation of the Web service are primarily depending on the range it reaches the customer’s requirements. In most cases, the customer of the Web service feels that he is spending for the service which is undelivered. This is because the customer always thinks that the real functionality of the web service is not reached. This will lead to change of the service frequently. In this paper, a framework is proposed to evaluate the Quality of Service (QoS) and its cost that makes the optimal correlation betwe...

Enhancing Web Service Discovery and Monitoring with Quality of Service Information

Practical Usage of Standards and Specifications, 2008

Web services provide a fundamental technology for developing service-oriented systems by leveraging platform-independent interface descriptions (WSDL) and a flexible message encoding (SOAP). Beside the functional description, quality of service (QoS) issues are currently not part of the Web service standards stack, although they provide valuable metadata of a Web service such as performance, dependability, security, or cost and payment. This additional information can be used to greatly enhance service discovery, selection, and composition. As a result of the latest research that is dedicated to this area, this chapter deals with the various ways of describing, bootstrapping, and evaluating QoS attributes. A strong focus is laid on client-side QoS assessment and the arising problems. Furthermore, a method to analyze Web service interactions by using our evaluation tool and extracting important QoS information without any knowledge about the service implementation will be presented and thoroughly explained. Usually, taking performance measures for a specific Web service requires access to the service implementation or at least the server machine where it is hosted. This chapter will address a way to bootstrap the most important performance and dependability values form the client's perspective, and therefore overcoming these restrictions.

Towards a Comprehensive View of Web Services QoS Models

International Journal of Multimedia and Ubiquitous Engineering, 2015

In a growing web services environment, the usage, design and composition methods of web services require proper and reliable information about web services quality. Qualityof-Service (QoS) is usually referred to the non-functional characteristics of web services which can be used as an important role to differentiate between different web services. In order to select the best web services among those with similar functionality, it is important for the web requester to have a mechanism to rank them and also from the service providers side to ensure that their web services are according to the agreed QoS. Currently there is no standard manner to define the QoS characteristics of web services. Many studies have shown different categorization of QoS which led to the issue of semantic interoperability of QoS. One way to understand the QoS, is to identify all its possible requirements for web services. This paper is an attempt to explore some of the QoS issues which are essential for web services. It first proposes a QoS framework which suggests considering QoS for web services along four different views. Each view is representing a particular relevant facet of QoS models. The main contribution of this paper is to show that there is a big quantity and variety of interpretations of various service quality concepts and models and gives the reasons why there is no holistic QoS modeling approach.

Quality of service for web services

2004

The World Wide Web is evolving from being a pure information repository to a more functional and service oriented platform thanks to technologies such as Web Services. This technology offers a homogeneous representation of Web elements and the ways they are communicating that make it possible to deal with the inherent structural and behavioural heterogeneities of the Web. A Web service can be seen as an autonomous functional element that is loosely coupled to other Web services and can be discovered and deployed in Web-based applications. Autonomity and loose coupling make Web services a viable light weight complementary componentbased approach for design and development of dynamic distributed systems for more heavy weight solutions such as OMG's CORBA and Microsoft's DCOM. In this paper, we take the position that if Web Services are going to be considered as reusable commercial of-the-shelf (COTS) components, their Quality of Service (QoS) needs to be expressed explicitly and measured independently. More specifically, we present and discuss possible quality aspects that need to be represented and quantified for Web Services.

Quality of Services Requirements for Web Services

2015

This document describes quality-of-service (QoS) requirements for web services. With the dispersal of web services as a business solution in enterprise application, the importance of QoS for web services is increasing rapidly to the service providers and the clients. Providers need to specify and guarantee the QoS in their web services to remain competitive and achieve the highest possible revenue from their business while the clients desire to have a good service performance in terms of very high availability, shorter response time, accuracy, etc. However, due to the dynamic and unpredictable characteristics of the web services, it is not an easy task to provide the desired QoS for web service users. Even, different web service applications with different QoS requirements will compete for network and system resources such as bandwidth and processing time. But, an enhanced QoS for a web service will bring competitive advantage for service provider. To provide such a better QoS, it i...

Experiments results and large scale measurement data for web services performance assessment

… , 2009. ISCC 2009. IEEE …, 2009

Service provisioning is a challenging research area for the design and implementation of autonomic serviceoriented software systems. It includes automated QoS management for such systems and their applications. Monitoring and Measurement are two key features of QoS management. They are addressed in this paper as elements of a main step in provisioning of self-healing web services. In a previous work [1], we defined and implemented a generic architecture applicable for different services within different business activities. Our approach is based on meta-level communications defined as extensions of the SOAP envelope of the exchanged messages, and implemented within handlers provided by existing web service containers. Using the web services technology, we implemented a complete prototype of a service-oriented Conference Management System (CMS). We experienced our monitoring and measurement architecture using the implemented application and assessed successfully the scalability of our approach under the French grid5000. In this paper, experimental results are analyzed and concluding remarks are given. WS Requester 2 WS Requester 1 WS Provider 1 WS Provider 2 ….

Probabilistic QoS Analysis of Web Services

Lecture Notes in Computer Science, 2013

In such a competitive world, quality assurance can make the difference between a successful business and bankruptcy. For Internet services, the presence of low performance servers, high latency or overall poor service quality can translate into lost sales, user frustration and customers lost. In this paper, we propose a novel method for QoS metrification based on Hidden Markov Models. The techniques we show can be used to measure and predict the behavior of Web Services under several criteria, and can thus be used to rank services quantitatively rather than just qualitatively. We demonstrate the feasibility and usefulness of our methodology by drawing experiments on real world data. Our results have shown how our proposed methods can help the user to automatically select the best available Web Service based on several metrics, among them system predictability and response times variability.

Verity: a QoS metric for selecting web services and providers

Fourth International Conference on Web Information Systems Engineering Workshops, 2003. Proceedings., 2003

With the proliferation of web services, quality of service serves as a benchmark to differentiate the services and their providers. As of today, a wide spectrum of attributes have been identified to account for the quality of a service like availability, reliability, servability, performance, reputation and so on. Reputation has been measured as an average user rating and we argue that the user perception alone is not sufficient to indicate the reputation. It is necessary to measure how trustworthy the provider has been in complying with the agreed levels in the SLA. To quantify the consistency in compliance levels, we introduce a new QoS attribute termed verity and propose an architecture to quantify it. We argue that verity should be taken into account for a quality driven selection and composition of web services. Reputation, when expressed as a vector of user rating, compliance and verity is a more intuitive indicator of the provider's trustworthiness.