Self-adaptable media service architecture for guaranteeing reliable multimedia services

Service Oriented Architecture (SOA) introduced the web services as distributed computing components that can be independently deployed and invoked by other services or software to execute composite services that represent an end-to-end business process. An important problem in the SOA is the web service selection and composition problem which involves selecting the right web services mix to construct the best service composition that achieves the consumers Service Level Agreement (SLA) requirements. In this chapter we propose different methods to solve the problem of the business processes execution engine web service selection and services composition construction in the Service Oriented Architecture (SOA).  The chapter provides different mechanisms to improve the web services selection and composition using dynamic techniques. The main goal is to satisfy the services' requirements expressed as the SLA and to enhance the services selection and composition by increasing the availability and decreasing the response time of the service compositions.

In recent years, the use of distributed systems by software industries and academic organizations has been increased in many folds. Therefore, the web services and a service-oriented style of architecture becomes the basis for a new generation of distributed applications and system management tools. Web Services and Service-Oriented Architecture (SOA) play a significant role as a middleware for software interoperability. These technologies deploy practice for ebusiness or Enterprise Application Integration (EAI). With the success of such deployments, Quality of Service (QoS) properties such as response time, availability and service costs are in high demands for SOA-based interoperability. A service composition in Service Oriented Architecture (SOA) environment is developed dynamically by integrating services from various service providers. There may be situations where services become faulty, resulting in violation of end to end Quality of Service (QoS) constraints. This paper proposes an approach to overcome this problem of faulty service reconfiguration. The work focuses on identifying the faulty services and their replacement on the basis of QoS constraints. In spite of modifying the whole composition, reconfiguration to the faulty region shall reduce the overheads of computations and service distractions in service delivery. The proposed approach presented in this paper is compared with various other prevalent service composition strategies.

Web Services Composition (WSC) is one of the main benefits of Service Oriented Architecture (SOA), however, its optimization is still a highly discussed research topic. In order to have an optimal composition, and therefore the best composite service, the composition mechanism must meet the requirements and issues of this process. Among the most important needs, we focus on the quality of web services involved, since the functional properties are not sufficient to determine the most appropriate service to meet the business goal. Researchers in this area propose different approaches and architectures to integrate Quality Of Service (QoS) values as a selection criterion, but they don't mention how to automatically generate those information and they don't consider the QoS values variations. They evaluate the QoS once and use calculated values in a static way. In our research work, we propose to automate the web service database filling. So, we don't have to manually read the WSDL file and extract necessary information for each operation. Moreover, we propose a QoS monitor component to calculate and update stored QoS values.

Today, many have attempted to provide multimedia services using IP over Satellite broadband infrastructure. The traffic complexity and real-time constraints of the multimedia services pose challenges to guarantee the delivery of packets end-to-end. At present, Quality of Service (QoS) in the router’s forwarding plane provides traffic differentiation capability in the traditional terrestrial networks. Traditional networking systems that implement QoS have packet classification and dropping mechanisms in the network edge and strong shapers and schedulers in the network core. In this paper, we clearly show that adapting the traditional QoS techniques to satellite medium will not optimize multimedia and other real-time broadband services. We also propose a new QoS architecture that provides a mechanism to optimize multimedia services over expanded broadband offering. In addition, we clearly establish in this paper using simulation results, that the proposed architecture is necessary to provide service guarantees for multimedia traffic over expanded broadband satellite networks. The results provided in the paper demonstrate that the proposed architecture has lower delay and jitter and higher packet delivery ratio compared to no QoS or partial QoS implementations.

Background/Objectives: The primary objective of the study is to evaluate the performance of Composite Web Service based on the parameters relating to Quality of Service by using statistical methodologies. Methods/Statistical Analysis: By using Web Service Crawler Engine we have collected data on eleven parameters of interest from a more number of Web Services. Among the eleven parameters we have selected six parameters of importance using the sampling of thirty Web Services. We have constructed the weight matrix for the parameters. By using Web Services Relevancy Function ranking has been done for three different scenarios. Using Spearman's Rank Correlation Coefficient we have compared the scenarios. Findings: The graphical representation of the three scenarios shows varying pattern. The Spearman's Rank Correlation coefficient of the Web Services Relevancy Function varied widely among the sampled Web Services. F-Test revealed that there are no significant differences in respect of weights of Quality of Web Services for three different scenarios. We concluded that weight assigned for Quality of Service parameters in Scenario I is preferred than the scenarios II and III through the evaluations. Application/Improvements: The technique developed in this research paper can be applied for the comparison of Web Services during discovery to enhance the performance of the Composite Web Service.

Quality of Service (QoS) has been widely used to support dynamic Web Service (WS) selection and composition. Due to the volatile nature of QoS parameters, QoS prediction has been put forward to understand the trend of QoS data volatility and estimate QoS values in dynamic environments. In order to provide adaptive and effective QoS prediction, we propose a WS QoS prediction approach, named WS-QoSP, based on the technique of forecast combination. Different from the existing QoS prediction approaches that choose a most feasible forecasting model and predict relying on this "best" model, WS-QoSP selects multiple potential forecasting models, combines the results of the selected models to optimize the overall forecast accuracy. Results of real data experiments demonstrate the diversified forecast accuracy gains by using WS-QoSP.

Service Oriented Architecture (SOA) has been widely adopted by industries due to its ability to provide increased interoperability among heterogeneous systems. SOA is realized through web services which can be either based on the style of Remote Procedure call(RPC) and SOAP protocol or on the Representational State Transfer(REST) style and HTTP. RESTful web services are increasingly becoming popular in the industry because of their simplicity, uniform interface, statelessness and cacheability benefits. The ability to efficiently select and integrate appropriate heterogeneous services available on the web dynamically at runtime is essential in the development of the applications based on web services. Whenever a single web service cannot satisfy the functionality required by the user, there should be a possibility to combine several existing services together in order to fulfill the request. This need has triggered a considerable number of research efforts on the composition of web services. Although several works have focused on the composition of SOAP based web services, there has not been adequate effort towards the composition of RESTful services. However, due to the above- mentioned advantages offered by the RESTful web services, it will be beneficial to design an application as a composition of such RESTful services. Towards this objective, this paper investigates two different approaches for composing the REStful web services specifically designed for health care domain, one using the Jopera tool and another using hypermedia.

To deal with Web service dynamicity and changes of application constraints in open distributed environment, a coordination model for dynamic service composition is presented. Based on the separation of concerns, there are three different categories of entities in a Web service-based application: Web service, role and coordinator. The Web service is only responsible for performing pure functional service, and carrying out the task assigned by the role; the role is an abstraction for certain properties and functionalities, responsible for binding Web service according to constraints, and actively coordinating Web service to achieve coordination requirements; the coordinator is responsible for the coordination among roles by imposing coordination policies and binding constraints. The logic separation of Web services, roles, and coordinators in the model, decouples the dependencies between the coordinators and Web services. Thus, the model shields the coordinator layer from the dynamicity of Web services. Finally, a vehicle navigation application including traffic control Web services, GPS Web services and a navigator is illustrated how the model can be used to achieve the interaction adaptation by means of dynamic composition of Web service.

Web services allows interaction of versatile applications irrespective of their platform, language and locations by utilizing generic and reliable services that can used as application building block. Business workflows can be implemented using composite web services. As more and more web services are evolving now, choosing the appropriate web service based of the Quality of Service (QoS) metrics is a tedious task now. Among all QoS metrics, reliability plays a vital role. Non-functional metrics of reliability are categorized as availability, performance and interoperability. In this paper, a framework model is proposed to optimize the performance in dynamic composite web service using caching technique.

Web service composition (WSC) is the task of combining a chain of connected single services together to create a more complex and value-added composite service. Quality of service (QoS) has been mostly applied to represent nonfunctional properties of web services and differentiate those with the same functionality. Many research has been done on QoS-aware service composition, as it significantly affects the quality of a composite service. However, existing methods are restricted to predefined workflows, which can incur a couple of limitations, including the lack of guarantee for the optimality on overall QoS and for the completeness of finding a composite service solution. In this paper, instead of predefining a workflow model for service composition, we propose a novel planning-based approach that can automatically convert a QoS-aware composition task to a planning problem with temporal and numerical features. Furthermore, we use state-of-the-art planners, including an existing one and a self-developed one, to handle complex temporal planning problems with logical reasoning and numerical optimization. Our approach can find a composite service graph with the optimal overall QoS value while satisfying multiple global QoS constraints. We implement a prototype system and conduct extensive experiments on large web service repositories. The experimental results show that our proposed approach largely outperforms existing ones in terms of solution quality and is efficient enough for practical deployment.

Service Oriented Architecture (SOA) refers to an architectural paradigm that describes how organizations, people and systems provide and use services to achieve their goals. Moreover, with the evolution of SOA, the focus in software development has shifted from applications to reusable services. Besides, reuse in SOA has more focused on service composition rather than reuse of existing implementations to build new services with additional functionalities. The preferred way to realize SOA remains web services which explain our interest in promoting reuse of Web services by managing variability. In this paper, we propose a model driven method for managing Web service's variability based on MDA (Model Driven Architecture). In fact, through MDA, the method enables the automation of Web service's realization regardless of the supported platforms. Moreover, we present a WSDL extension meta-model called VarWSDL which enhances Web services by variability notions. That permits Web services reuse.

SOA (Service-oriented Architecture) is becoming the major architecture for building complex Web service systems. In SOA, the lifecycle of Web services consists of four stages: service publication, service discovery, service binding and service execution. Faults may occur in any stage and cause a failure of service. The reliability of services depends on not only the faults of the remote services itself, but also the faults that may occur in any SOA stage. Designing an effective and accurate reliability prediction model for Web services has become an important and necessary task. This study first proposes a staged reliability model for atomic services, which structures the reliability estimation based on the faults that may occur at each stage. Then, the reliability of composite services or service systems can be estimated based on this staged model. An experiment is conducted to study the influence of failures at each stage on the reliability of atomic services and a case study is designed to demonstrate the reliability of composite services using our staged model. In addition, the accuracy of our approach is investigated by comparing it against CBRM (component-based reliability model). Sensitivity analysis is also performed to identify critical service. Experimental results show that our staged model can obtain higher reliability prediction accuracy and is more suitable for Web services than traditional model.

The Business Process Execution Language (BPEL) has become the standard in Web service composition, so that been adopted by industries to create mission critical services. The business process reliability especially business process consistency when some services failed is critical to composite services especially involving various organizations. However, it is difficult to conduct business process reliability testing for composite services due to complex business process in service composition, remote deployed services and long time testing duration. Little research is done to test fault tolerance capabilities of composite services only from low level. This paper proposes a technique on how to test the reliability of composite service defined in BPEL from the view of business semantics with little cost using fault injection. We present an approach for reliability testing of web services by using service stubs with semantic faults instead of real services which can be placed at service provider side or service consumer side. Dislike existing studies, we focus on how to find the reliability problems associating with business process - called semantics as the problems are not pure coding error but faults related to business process. In addition, the behavior of composite services in BPEL is analyzed when there are faults in orchestrated services invoked. Finally, a case study is given to show the whole process of reliability testing for composite web service.

Web services – a new breed of self-contained, self-describing, modular applications published, located, and invoked across the Web – handle functions, from simple requests to complicated business processes. They are defined as network-based application components with a services-oriented architecture (SOA) using standard interface description languages and uniform communication protocols. SOA enables organizations to grasp and respond to changing trends and to adapt their business processes rapidly without major changes to the IT infrastructure. The Inaugural International Conference on Next-Generation Web Services Practices (NWeSP'05) attracted researchers who are also the world's most respected authorities on the semantic Web, Web-based services, and Web applications and services. NWeSP'05 was held in cooperation with the IEEE Computer Society Task Force on Electronic Commerce, the Technical Committee on Internet, and the Technical Committee on Scalable Computing. This special issue presents eight papers focused on different aspects of Web services and their applications. Papers were selected based on fundamental ideas and concepts rather than the thoroughness of techniques employed. Papers are organized as follows: <I>Taher et al.</I> present the first paper, on a Quality of Service Information and Computational framework (QoS-IC) supporting QoS-based service selection for SOA. The framework's functionality is expanded using a QoS constraints model that establishes an association relationship between different QoS properties and is used to govern QoS-based service selection in the underlying algorithm. Using a prototype implementation, the authors demonstrate how QoS constraints improve QoS-based service selection and save consumers valuable time. Due to the complex infrastructure of web applications, response times perceived by clients may be significantly longer than desired. To overcome some of the current problems, <I>Vilas et al.</I>, in the second paper, propose a cache-based extension of the architecture that enhances the current web services architecture, which is mainly based on program-logic or protocol-dependent optimization. In the third paper, Jo and Yoo present authorization for securing XML sources on the Web. One of the disadvantages of existing access control is that the DOM tree must be loaded into memory while all XML documents are parsed to generate the DOM tree, such that a lot of memory is used in repetitive search for tree to authorize access to all nodes in the DOM tree. The complex authorization evaluation process required thus lowers system performance. Existing access control fails to consider information structure and semantics sufficiently due to basic HTML limitations. The authors overcome some of these limitations in the proposed model. In the fourth paper, Jung and Cho propose a novel behavior-network-based method for Web service composition. The behavior network selects services automatically through internal and external links with environmental information from sensors and goals. An optimal service is selected at each step, resulting in a globally optimal service sequence for achieving preset goals. The authors detail experimental results for the proposed model by comparing them with rule-based system and user tests. <I>Kong et al.</I> present an efficient method in the fifth paper for merging heterogeneous ontologies – no ontology building standard currently exists – and the many ontology-building tools available are based on different ontology languages, mostly focusing on how to create, edit and infer the ontology efficiently. Even ontologies about the same domain differ because ontology experts hold different view points. For these reasons, interoperability between ontologies is very low. The authors propose merging heterogeneous domain ontologies by overcoming some of the above limitations. In the sixth paper, Chen and Che provide polynomial-time tree pattern query minimization algorithm whose efficiency stems from two key observations: (i) Inherent redundant "components" usually exist inside the rudimentary query provided by the user, and (ii) nonedundant nodes may become redundant when constraints such as co-occurrence and required child/descendant are given. They show that the algorithm obtained by first augmenting the input tree pattern using constraints, then applying minimization, invariably finds a unique minimal equivalent to the original query. Chen and Che present a polynomial-time algorithm for tree pattern query (TPQ) minimization without XML constraints in the seventh paper. The two-part algorithm is a dynamic programming strategy for finding all matching subtrees within a TPQ. The algorithm consists of one for subtree recognization and a second for subtree deletion. In the last paper, <I>Bagchi et al.</I> present the mobile distributed virtual memory (MDVM) concept and architecture for cellular networks containing server-groups (SG). They detail a two-round randomized distributed algorithm to elect a unique leader and co-leader of the SG that is free of any assumption about network topology, and buffer space limitations and is based on dynamically elected coordinators eliminating single points of failure. As guest editors, we thank all authors featured in this special issue for their contributions and the referees for critically evaluating the papers within the short time allotted. We sincerely believe that readers will share our enjoyment of this special issue and find the information it presents both timely and useful.

There is a massive upsurge in data traffic over the Internet due to multimedia services. The upcoming heterogeneous broadband wireless access networks (BWANs) provide higher data rates, increased capacity, and enhanced network coverage. Since the smart phone usage and multimedia service demand is increasing at a much faster pace as compared to the capacity and resources of the underlying network technology, adaptive multimedia services are essential to provide satisfactory quality of experience (QoE). The focus of this chapter is to discuss the adaptive techniques to provide better multimedia services to heterogeneous users in next-generation networks. These techniques consist of video streaming optimization using MPEG-DASH, video caching schemes, quality aware video transcoding, web optimization of multimedia services, and user-centric cross-layer optimization.