QoS Properties Research Articles

An Architecture for Web Service Similarity Evaluation Based on their Functional and QoS Aspects

By increasing popularity of SOC, using Web services in applications has increased too. SOC creates a loosely coupled environment in which the actual execution environment might differ significantly from the one with the presupposed conditions during application design. Therefore, although an appropriate Web service might have been selected, by passing time, the Web service may not be efficient enough or may not be applicable under specific conditions. For service-oriented systems to be flexible and self-adaptive, it is necessary to automatically select and use a similar service instead of the one which causes the above mentioned problems. Finding a similar service means specifying the proper services which fulfill the same requirements as those fulfilled by the problematic service. In most of the previous works, a number of the best services (k) are selected and ordered based on functional similarity. The user must select one of these services based on his/her preferences. One important metric in selecting a similar service is considering QoS properties and user preferences about QoS. Because of the importance of this issue, in the present paper, an architecture is proposed in which, in addition to functional similarity, QoS properties and user preferences are also considered in selecting a similar service.

An evidence-based scheme for web service selection

Existing studies on the web service selection problem focus mainly on the functional QoS properties of the service rather than the consumer satisfaction and trust aspects. While a good QoS enhances the reputation of a service, different consumers invariably hold differing views of the service contents. Some service reputation approaches primarily consider the consumer's prior experience of the service via opinion feedback system, may neglect the effect of social trust transition in the recommendations of others. As a result, the problem of reaching consensus on the level of consumer trust regarding service becomes one of key issues in service selection. This study proposes a trust-based service selection model to estimate the degree of consumer trust in a particular service based on the consumers' direct experience and indirect recommendation of the service. In the proposed approach, the degree of consumer trust is correctly estimated by extending Dempster---Shafer evidence reasoning theory to the reputation computation using consumers' direct experience and incorporating Josang's belief model for solving the trust transition problem in the indirect recommendation of the service. The proposed model effectively enables deception detection by means of existing bodies of evidence, and therefore excludes the fraudulent evidence of malicious evaluators from the selection process. In addition, a quality index is proposed to help third party (TTP) examine the body of evidence and make the outranking result more reliable. Importantly, the quality index is based not only on the confidence degree of the evidence, but also on the support degree, and therefore discovers the effects of intentional negative assessments. The validity of the proposed approach is demonstrated numerically by means of two service selection examples.

Web Service Selection Based on Fuzzy Synthetic Evaluation

Due to their complexity and the involvement of consumer’s fuzzy perceptions of QoS, non-functional QoS attributes are not easy to measure for web services. Hence, in order to enable effective QoS-aware web service selection, a new QoS web service selection approach, based on fuzzy synthetic evaluation, is proposed in this paper. The approach takes both functional attributes and non-functional QoS requirements into account for service selection. The approach has been empirically evaluated via a experiment. The results show that our proposed approach is effective under user’s vague perception.

Expectation Value Calculation of Grid QoS Parameters Based on Algorithm Prim

From the perspective of selecting service by QoS attributes, a computation method of QoS expectation value, which is based on Algorithm Prim, was presented to provide support for selection of service. On the basis of the ability of service providers, by Algorithm Prim, this method succeded in calculating a set of balanced expectation values of QoS. Selection of service based on these QoS values would be beneficial to optimization of system resources and protection of the users of those services. An example with analysis has been provided to demonstrate the feasibility and effectiveness of the method.

QoS-awared replica placement techniques in data grid applications

Quality of service is one of the most important factors for successful grid applications. However, individual QoS constraint (IQC) and QoS-awared replica placement have not yet been well addressed in the existing data grid. Existing QoS-awared replica placement algorithms neither can support multiple QoS attributes, nor have good scalability. In this paper, a three-phrase QoS-awared replica placement algorithm based on matrix, namely TP-GABMAC, is presented to solve these problems. Furthermore, a replica ring mechanism is introduced to maintain replica consistency and manage update conflicting. Experiments and analysis demonstrate that the proposed algorithms are not only stable and scalable, but also work well under different network topologies, access patterns and workloads.

A formalized approach for designing a P2P‐based dynamic load balancing scheme

AbstractQuality of service (QoS) is attracting more and more attention in many areas, including entertainment, emergency services, transaction services, and so on. Therefore, the study of QoS‐aware systems is becoming an important research topic in the area of distributed systems. In terms of load balancing, most of the existing QoS‐related load balancing algorithms focus on Routing Mechanism and Traffic Engineering. However, research on QoS‐aware task scheduling and service migration is very limited. In this paper, we propose a task scheduling algorithm using dynamic QoS properties, and we develop a Genetic Algorithm‐based Services Migration scheme aiming to optimize the performance of our proposed QoS‐aware distributed service‐based system. In order to verify the efficiency of our scheme, we implement a prototype of our algorithm using a P2P‐based JXTA technique, and do an emulation test and a simulation test in order to analyze our proposed solution. We compare our service‐migration‐based algorithm with non‐migration and non‐load‐balancing approaches, and find that our solution is much better than the other two in terms of QoS success rate. Furthermore, in order to provide more solid proofs of our research, we use DEVS to validate our system design. Copyright © 2010 John Wiley & Sons, Ltd.

Agent service matchmaking algorithm for autonomic element with semantic and QoS constraints

Agent service description and matchmaking problem for autonomic element has been taken as one of the most important issue in the field of autonomic computing based on agent and multi-agent system. Considering the semantic and QoS for capability description of agent service are two important issues during matchmaking, the factors of semantic and QoS during matchmaking are considered together, and an agent service description model named ASDM _ SQ is proposed. On basis of this model, a matchmaking algorithm with semantic and QoS constraints named ASMA _ SQ is presented to find the agent service satisfied both the given semantic similarity threshold and optimal QoS performance. The proposed algorithm lies over two fundamental processes: semantic similarity matchmaking and QoS matchmaking. During QoS matchmaking, evaluation mechanism of confidence of individual QoS attributes, i.e. fidelity factor is introduced to overcome drawbacks such as subjectiveness and unfairness and improve the self-configuration capability for agent element. Simulation experiments demonstrate the effective and correction of our algorithm for agent service matchmaking, and perform better QoS performance than other existing algorithm, which can further show that our algorithm has better compromise between attribute quality and users’ evaluation when selecting agent service.

Autonomic Software Component QoS Matchmaking Algorithm Based on Fidelity Factor in Agent-Based Autonomic Computing System

Autonomic software component (ASC) QoS matchmaking problem for autonomic element has been taken as one of the most important issue in field of autonomic computing based on agent. Aimed at overcoming drawbacks such as subjec-tiveness and unfairness, and improving the self-configuration capability for autonomic element, we introduce evalua-tion mechanism of confidence of individual QoS attributes during ASC QoS matchmaking, i.e., fidelity factor for each attribute, and propose an ASC QoS matchmaking algorithm based on fidelity factor. Simulation experiments demon-strate that our proposed algorithm performs best performance in terms of QoS than other existing algorithms, and has better compromise between attribute quality and users’ evaluation when selecting ASC.

Making Web Services Tradable: A Policy-Based Approach for Specifying Preferences on Web Service Properties

In service-oriented architectures, applications are developed by incorporating services which are often provided by different organizations. Since a service might be offered under different configurations by various different organizations, sophisticated service selection and negotiation algorithms are required. Policies capture the conditions under which services are offered or requested and thereby constrain the negotiation space. However, current policy languages are ill-suited to realize beneficial trade-offs within a negotiation, since they support only Boolean decisions and cannot capture all relevant service information. Therefore, we present a novel policy language in this work that provides two main contributions: (i) we enable the specification of constraints on functional as well as non-functional properties of Web services. The functional properties include data objects and the behaviour, whereas the non-functional properties include QoS attributes. (ii) Given such constraints,we show how the concept of utility function policies can be used to define cardinal preferences over functional as well as non-functional properties. This is required to rank Web service offers, define their prices, and consequently to realize automated negotiations between service providers and requesters.

Multi-QoS Criteria Based Selection of Web Services by Using AHP Approach

QoS-based Web service ranking problem is complex due to the diverse characteristic of QoS properties and the trade-off issue between them. A ranking mechanism needs to take into account different ways to effectively handle different types of QoS properties measured by different methods with different units and value types, as well as to unify those various QoS measurements in a fair comparison method. In this paper, we present a novel method for ranking and selecting Web services by introducing an extensible QoS model and a corresponding ranking algorithm. The QoS model takes into account the following considerations: different roles and preferences of users and system brokers in specifying QoS demand, different important levels between required QoS constraints and optional QoS preferences, and different QoS value comparison rules with respect to value types and comparative effects of QoS properties. AHP, a multiple criteria decision making method, is applied as an underlying mechanism for developing a flexible and effective ranking algorithm. The experimental results verify that our proposal produces significant achievement with our extensible QoS model and the new service ranking algorithm.

QoS-aware service evaluation and selection

Abstract Making the provision of services QoS-aware is to the advantage of both clients and providers in the e-business domain. This paper studies the problem of providers that receive multiple concurrent requests for services demonstrating different QoS properties. It introduces the “Selective Multiple Choice Knapsack Problem” that aims to identify the services, which should be delivered in order to maximise the provider’s profit, subject to maximum bandwidth constraints. This problem is solved by a proposed algorithm that has been empirically evaluated via numerous experiments.

Special issue on mathematical methods in network management

Special issue on mathematical methods in network management

WS-CONTRACT ESTABLISHMENT WITH QOS: AN APPROACH BASED ON FEATURE MODELING

Electronic contracts describe inter-organizational business processes in terms of supply and consumption of electronic services (commonly Web services). The establishment of e-contracts in a particular business domain usually involves a set of well-defined common and variable properties. These properties are not fully exploited by the existing e-contract establishment approaches. Feature modeling is a software engineering technique that has been widely used for capturing and managing commonalities and variabilities of product families in the context of software product line. This paper presents a feature-based approach to support Web services e-contract (WS-contract) establishment. The approach aims at improving the information structure and reuse of WS-contracts, including the QoS attributes. Features are used to represent possible WS-contract elements in order to drive WS-contract template instantiation, thus acting as a configuration space manager. A toolkit named FeatureContract was developed to automatically support the proposed approach. A case study was carried out within the telecom context to show the approach feasibility.

Automatic Web services composition based on SLM

Motivated by the problem of simplifying the manual operation of the composition process, we propose an approach to automatically compose available Web services to fulfill user’s goal based on the assumption that there are a set of alternative Web services with similar functionality and different QoS properties. A formal model (i.e. semantic links matrix, SLM for short) is proposed to store semantic links values for the Web services with semantic relationship and QoS of Web services. The SLM provides a search place for a backward-search planning algorithm, at the same time; the QoS criteria make a rational and effective decision among a number of similar Web services. The function and some properties of the algorithm are analyzed. The approach can improve the correctness and flexibility for Web services composition and satisfy the local QoS attribute.

IEEE 802.20: Mobile Broadband Wireless Access for the Twenty-First Century

Access to networked data and information services has taken on an ever increasing importance to users for business, entertainment, and social networking applications. Users want high-speed, high-reliability, and high-quality access to these information services to be ubiquitous and available when they are fully mobile. Having these services available in a mobile environment also provides additional opportunities for service providers to enrich their offerings with location- based services. This article describes the IEEE 802.20 standard that was developed to meet the unique requirements for supporting high-speed data services while at the same time supporting full user mobility. It is a standard optimized to provide (IP-based) broadband wireless (Internet) access in a mobile environment, thereby affording network operators superior performance (e.g., higher data rates, lower latency) and lower costs as compared to networks built using standards that are not optimized for that purpose. The standard includes an OFDM wideband mode and a 625k-multicarrier mode. TDD duplexing is supported by both the 625k-MC mode and the OFDM wideband mode; FDD duplexing is supported by the OFDM wideband mode. Both modes are designed to support a full range of QoS attributes, making this technology suitable to support real-time streaming service that has low delay and jitter requirements, as well as near-real-time data services, where low error rate can be traded off for delay. These characteristics of the 802.20 standard make it suitable to meet user requirements for wireless mobile access well into the twenty-first century.

Building self-optimized communication systems based on applicative cross-layer information

This article proposes the Implicit Packet Meta Header (IPMH) as a standard method to compute and represent common QoS properties of the Application Data Units (ADU) of multimedia streams using legacy and proprietary streams’ headers (e.g. Real-time Transport Protocol headers). The use of IPMH by mechanisms located at different layers of the communication architecture will allow implementing fine per-packet self-optimization of communication services regarding the actual application requirements. A case study showing how IPMH is used by error control mechanisms in the context of wireless networks is presented in order to demonstrate the feasibility and advantages of this approach.

QoS-aware web services selection with intuitionistic fuzzy set under consumer’s vague perception

Appropriate application of service selection based on QoS-aware can bring great benefits to service consumers, as it is able to reduce redundancy in search. It also generates advantages for service providers who deliver valuable services. However, non-functional QoS attributes are not easy to measure due to their complexity and the involvement of consumer’s fuzzy perceptions of QoS. In this paper, a new decision model under vague information is proposed. It extends Max–Min–Max composition of intuitionistic fuzzy sets (IFS) for selection of web services. Furthermore, an improved fuzzy ranking index is proposed to alleviate the bias of existing approaches. The index aggregates both concord and discord degrees of the decision maker’s satisfaction in order to analyze the synthetic satisfaction degree for web services. In addition, an example of QoS-aware web services selection is illustrated to demonstrate the proposed approach. Finally, the proposed method is verified by a sensitivity analysis.

Making Web services tradable: A policy-based approach for specifying preferences on Web service properties

In service-oriented architectures, applications are developed by incorporating services which are often provided by different organizations. Since a service might be offered under different configurations by various different organizations, sophisticated service selection and negotiation algorithms are required. Policies capture the conditions under which services are offered or requested and thereby constrain the negotiation space. However, current policy languages are ill-suited to realize beneficial trade-offs within a negotiation, since they support only Boolean decisions and cannot capture all relevant service information. Therefore, we present a novel policy language in this work that provides two main contributions: (i) we enable the specification of constraints on functional as well as non-functional properties of Web services. The functional properties include data objects and the behaviour, whereas the non-functional properties include QoS attributes. (ii) Given such constraints, we show how the concept of utility function policies can be used to define cardinal preferences over functional as well as non-functional properties. This is required to rank Web service offers, define their prices, and consequently to realize automated negotiations between service providers and requesters.

Introducing a cross-layer interpreter for multimedia streams

In the context of multimedia and real-time systems, this article introduces a generic interpreter of QoS properties (xQoS-Interpreter) for the Application Data Units (ADUs) composing standard and proprietary multimedia streams. This approach is intended to make the QoS properties of ADUs publicly available to any mechanism of the underlying communication system. The use of this information allows for cross-layer QoS optimization of the communication services taking the actual per-packet requirements of the applications into account. A case study showing how the xQoS-Interpreter is used at transport layer to seamlessly optimize the perceived QoS of an end-to-end video transmission is presented. In this scenario, the xQoS-Interpreter is used to optimize a TCP-friendly Rate Control mechanism (TFRC) over congested wireless network services in order to demonstrate the feasibility and advantages of our approach.

QUORUM—Quality of Service in Wireless Mesh Networks

Wireless mesh networks (WMNs) can provide seamless broadband connectivity to network users with low setup and maintenance costs. To support next-generation applications with real-time requirements, however, these networks must provide improved quality of service guarantees. Current mesh protocols use techniques that fail to accurately predict the performance of end-to-end paths, and do not optimize performance based on knowledge of mesh network structures. In this paper, we propose QUORUM, a routing protocol optimized for WMNs that provides accurate QoS properties by correctly predicting delay and loss characteristics of data traffic. QUORUM integrates a novel end-to-end packet delay estimation mechanism with stability-aware routing policies, allowing it to more accurately follow QoS requirements while minimizing misbehavior of selfish nodes.