Web Services Dependability

2010 ◽  
pp. 151-167
Author(s):  
Michael C. Jaeger ◽  
Matthias Werner

This chapter presents the definition of relevant terminology and a conceptual model of the basic terms. The chapter starts with the presentation of research in the area of dependability. Based on this, Web service concepts related to the dependability are introduced. The presentation leads into a statement identifying individual quality-of-service (QoS) characteristics for forming dependable Web services. Then, the chapter discusses the current status quo in the area of QoS-aware Web services. This part is divided into three subparts: description, management, and monitoring. This also identifies ongoing efforts as well as efforts that do not show present activity. By this discussion, this chapter puts research about dependability in relation with ongoing QoS-related efforts in the Web services domain. Thus it identifies how these efforts can be combined in order to form a dependable Web services platform.

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Haiteng Zhang ◽  
Zhiqing Shao ◽  
Hong Zheng ◽  
Jie Zhai

In the early service transactions, quality of service (QoS) information was published by service provider which was not always true and credible. For better verification the trust of the QoS information was provided by the Web service. In this paper, the factual QoS running data are collected by our WS-QoS measurement tool; based on these objectivity data, an algorithm compares the difference of the offered and measured quality data of the service and gives the similarity, and then a reputation evaluation method computes the reputation level of the Web service based on the similarity. The initial implementation and experiment with three Web services' example show that this approach is feasible and these values can act as the references for subsequent consumers to select the service.


2010 ◽  
pp. 114-150 ◽  
Author(s):  
Kyriakos Kritikos

As the Web service (WS) paradigm gains popularity for its promise to transform the way business is conducted, the number of deployed WSs grows with a fast rate. While sophisticated semantic discovery mechanisms have been devised to overcome the UDDI’s syntactic discovery solution in order to increase recall and precision, the amount of functionally equivalent WSs returned is still large. One solution to this problem is the description of the nonfunctional aspects of WSs, including quality of service (QoS). QoS encompasses the performance of WSs and can be used as a discriminating factor for refining WS advertisement results. However, most efforts presented so far are purely syntactic in nature and do not capture all aspects of QoS-based WS description, leading to imprecise syntactic discovery mechanisms. In this chapter, a definition of QoS for WSs is provided and its important role in WS management is emphasized. An analysis of the requirements that are imposed on the WS description and discovery processes based on QoS is given along with a review of related work in QoS-based WS description and discovery, highlighting the main deficiencies of recent approaches. Then, a complete semantic approach for QoS-based WS description and discovery is presented and analyzed. The chapter concludes by drawing directions for further research.


2019 ◽  
Vol 54 (6) ◽  
Author(s):  
Sawsan Ali Hamid ◽  
Rana Alauldeen Abdalrahman ◽  
Inam Abdullah Lafta ◽  
Israa Al Barazanchi

Recently, web services have presented a new and evolving model for constructing the distributed system. The meteoric growth of the Web over the last few years proves the efficacy of using simple protocols over the Internet as the basis for a large number of web services and applications. Web service is a modern technology of web, which can be defined as software applications with a programmatic interface based on Internet protocol. Web services became common in the applications of the web by the help of Universal, Description, Discovery and Integration; Web Service Description Language and Simple Object Access Protocol. The architecture of web services refers to a collection of conceptual components in which common sets of standard can be defined among interoperating components. Nevertheless, the existing Web service's architecture is not impervious to some challenges, such as security problems, and the quality of services. Against this backdrop, the present study will provide an overview of these issues. Therefore, it aims to propose web services architecture model to support distributed system in terms of application and issues.


2022 ◽  
Vol 22 (1) ◽  
pp. 1-31
Author(s):  
Marwa Daaji ◽  
Ali Ouni ◽  
Mohamed Mohsen Gammoudi ◽  
Salah Bouktif ◽  
Mohamed Wiem Mkaouer

Web service composition allows developers to create applications via reusing available services that are interoperable to each other. The process of selecting relevant Web services for a composite service satisfying the developer requirements is commonly acknowledged to be hard and challenging, especially with the exponentially increasing number of available Web services on the Internet. The majority of existing approaches on Web Services Selection are merely based on the Quality of Service (QoS) as a basic criterion to guide the selection process. However, existing approaches tend to ignore the service design quality, which plays a crucial role in discovering, understanding, and reusing service functionalities. Indeed, poorly designed Web service interfaces result in service anti-patterns, which are symptoms of bad design and implementation practices. The existence of anti-pattern instances in Web service interfaces typically complicates their reuse in real-world service-based systems and may lead to several maintenance and evolution problems. To address this issue, we introduce a new approach based on the Multi-Objective and Optimization on the basis of Ratio Analysis method (MOORA) as a multi-criteria decision making (MCDM) method to select Web services based on a combination of their (1) QoS attributes and (2) QoS design. The proposed approach aims to help developers to maintain the soundness and quality of their service composite development processes. We conduct a quantitative and qualitative empirical study to evaluate our approach on a Quality of Web Service dataset. We compare our MOORA-based approach against four commonly used MCDM methods as well as a recent state-of-the-art Web service selection approach. The obtained results show that our approach outperforms state-of-the-art approaches by significantly improving the service selection quality of top- k selected services while providing the best trade-off between both service design quality and desired QoS values. Furthermore, we conducted a qualitative evaluation with developers. The obtained results provide evidence that our approach generates a good trade-off for what developers need regarding both QoS and quality of design. Our selection approach was evaluated as “relevant” from developers point of view, in improving the service selection task with an average score of 3.93, compared to an average of 2.62 for the traditional QoS-based approach.


2021 ◽  
Author(s):  
Kian Farsandaj

In the last decade, selecting suitable web services based on users’ requirements has become one of the major subjects in the web service domain. Any research works have been done - either based on functional requirements, or focusing more on Quality of Service (QoS) - based selection. We believe that searching is not the only way to implement the selection. Selection could also be done by browsing, or by a combination of searching and browsing. In this thesis, we propose a browsing method based on the Scatter/Gather model, which helps users gain a better understanding of the QoS value distribution of the web services and locate their desired services. Because the Scatter/Gather model uses cluster analysis techniques and web service QoS data is best represented as a vector of intervals, or more generically a vector of symbolic data, we apply for symbolic clustering algorithm and implement different variations of the Scatter/Gather model. Through our experiments on both synthetic and real datasets, we identify the most efficient ( based on the processing time) and effective implementations.


Author(s):  
Evelina Pencheva ◽  
Ivaylo Atanasov

Parlay X is a set of Web Service interfaces. These interfaces are designed to provide open access to telecommunication network functions in order to hide underlying network technology, and its control protocol complexity, from application developers. The Parlay X “intelligence” is concentrated in a node called Parlay X Gateway which converts interfaces methods in protocol messages and vice versa. An inherent constraint on any implementation requires the Parlay X Gateway to govern the interface to the underlying network i.e., to provide a single point of contact at which vertical signaling is received from the network. This chapter presents a study on alternatives for Parlay X Web Service deployment in Internet Protocol based multimedia networks (IMS). The focus is set on Parlay X Web Services for application-driven quality of service (QoS) management and charging control. It is presented as an analysis of the interfaces. Particularly the discussion is about their applicability to Policy and Charging Control architecture in IMS. Going further, the Web Service interfaces are mapped onto network protocols that they affect, namely Session Initiation Protocol (SIP) and Diameter. On that base an improvement is suggested concerning Parlay X interfaces for QoS management without violating the specified interface functionality. The usage of Web Services is exemplified with an application for charging control based on the provided QoS.


2011 ◽  
Vol 08 (04) ◽  
pp. 291-302
Author(s):  
RAVI SHANKAR PANDEY

Web services are programs which perform some elementary business process of an application and are distributed over the Internet. These services are described, discovered and executed using standard languages WSDL, SOAP and UDDI. Proliferation of web services has resulted in intense competition between providers, which provide the same service. To survive in such a competitive environment, they need to advertise the quality of their service. Web service description language does not provide support to describe quality attributes. Recently, DAmbrogio proposed QOS model of web services based on a meta model of WSDL. In this paper, we present a platform to advertise QOS as declared by the service provider. This tool generates a WSDL file from Java code along with its quality of service attributes. It accepts Java code and a file containing quality attributes. These attributes include reliability, availability, and operation demand and operation latency. These attributes are included in WSDL file as a content of description element.


2014 ◽  
pp. 505-526
Author(s):  
Evelina Pencheva

This paper studies implementation issues of Parlay X “Multimedia Streaming Control” and “Application-driven Quality of Service” web services in the Evolved Packet System (EPS). EPS is defined as evolution of mobile communication networks with broadband radio interface and Internet Protocol (IP) based core. The main signalling protocols in EPS used for multimedia session management and quality of service control are respectively Session Initiation Protocol (SIP) and Diameter. The functional architecture for third party multimedia streaming control with guaranteed quality of service considers deployment of an application server which exposes web service interfaces toward applications and control protocols toward the network. In a role of mediation functionality, this application server is responsible for the translation between web services interface operations and control protocol messages. In addition, it needs to maintain synchronized state models that reflect both third party application view and protocol view. An approach to automated functional verification of such type of application server providing “Multimedia Streaming Control” and “Application-driven Quality of Service” web service interfaces is suggested. Use cases that illustrate the approach applicability are described.


Author(s):  
Bassam Al Shargabi ◽  
Osama Al-haj Hassan ◽  
Alia Sabri ◽  
Asim El Sheikh

Software is gradually becoming more built by composing web services to support enterprise applications integration; thus, making the process of composing web services a significant topic. The Quality of Service (QoS) in web service composition plays a crucial role. As such, it is important to guarantee, monitor, and enforce QoS and ability to handle failures during execution. Therefore, an urgent need exists for a dynamic Web Service Composition and Execution (WSCE) framework based on QoS constraints. A WSCE broker is designed to maintain the following function: intelligent web service selection decisions based on local QoS for individual web service or global QoS based selection for composed web services, execution tracking, and adaptation. A QoS certifier controlled by the UDDI registry is proposed to verify the claimed QoS attributes. The authors evaluate the composition plan along with performance time analysis.


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