Custom Windows Performance Counters Monitoring Mechanism for Measuring Quality of Service Attributes and Stability Coefficient Service-Oriented Architecture

Service-Oriented Architecture (SOA) has been widely used for different types of systems as their underlying architecture. The most popular technology that implements the SOA is web service. When several web services provide same functionalities, Quality of Service (QoS) of web services turn to be an important issue. In this study, monitoring is used in order to measure QoS attributes of web services in SOA. Several monitoring mechanisms have been proposed. Windows Performance Counters (WPC) is one of approaches for monitoring services at provider-side. However, WPC monitoring approach has a limitation and it can be employed just for WCF services. Moreover, predefined system counter values do not map to QoS values properly. In this research, a new provider-side monitoring mechanism which is based on Custom Windows Performance Counters (CWPC) is proposed in order to overcome current limitations. CWPC will be set to measure QoS attributes of web services such as response time, throughput and reliability properly. The results of CWPC monitoring are useful in taking decision in adjusting suitable monitoring interval for the system. Additionally, the result verifies that CWPC is an accurate monitoring approach for measuring QoS attributes. Besides that, this study also focuses on variability of QoS values which are obtained by monitoring of web services at different service invocation time. QoS values are variable and service consumers may experience various QoS values due to the fact that web services run in a distributed, dynamic, and unreliable environment which makes them exposed to faults and failures. In this research, a new Stability Coefficient is introduced to measure stability of a service based on historical QoS values that were obtained by monitoring the web service. Such a measure enables service consumers to find a stable and trustable service based on QoS attributes and it can increase consumer’s satisfaction. In this study, the Stability Coefficient is defined based on an average of different QoS attributes of service stability. The results confirm that the proposed Stability Coefficient is a proper criterion for determining stability of services in terms of their QoS attributes and a stable service with less QoS values variation has a high Stability Coefficient which may lead to more satisfaction to service consumer

INVESTIGATION OF THE ROLE OF SERVICE LEVEL AGREEMENTS IN WEB SERVICE QUALITY

Context/Background: Use of Service Level Agreements (SLAs) is crucial to provide the value added services to consumers to achieve their requirements successfully. SLAs also ensure the expected Quality of Service to consumers. Aim: This study investigates how efficient structural representation and management of SLAs can help to ensure the Quality of Service (QoS) in Web services during Web service composition. Method: Existing specifications and structures for SLAs for Web services do not fully formalize and provide support for different automatic and dynamic behavioral aspects needed for QoS calculation. This study addresses the issues on how to formalize and document the structures of SLAs for better service utilization and improved QoS results. The Service Oriented Architecture (SOA) is extended in this study with addition of an SLAAgent, which helps to automate the QoS calculation using Fuzzy Inference Systems, service discovery, service selection, SLA monitoring and management during service composition with the help of structured SLA documents. Results: The proposed framework improves the ways of how to structure, manage and monitor SLAs during Web service composition to achieve the better Quality of Service effectively and efficiently. Conclusions: To deal with different types of computational requirements the automation of SLAs is a challenge during Web service composition. This study shows the significance of the SLAs for better QoS during composition of services in SOA

Performance counter monitoring mechanism for measuring QoS attributes in SOA.

Nowadays, many similar web services with same functionalities have been developed around the world. When multiple web services provide same functionalities, Quality of Service (QoS) turns to an important issue. In this paper,monitoring is used in order to measure QoS attributes of web services in Service-Oriented Architecture (SOA). Windows Performance Counters (WPC) is a windows component which supports application monitoring. The main focus of this paper is applying performance counters for monitoring of web services in order to measure their QoS attributes such as response time and throughput at provider-side. We introduce CWPC monitoring approach in detail and we describe employing performance counter facilitate QoS measurement process. Additionally, the results of monitoring via performance counter for measuring QoS attributes such as response time and throughput are presented which can be considered for taking management decisions like adjusting proper monitoring interval

Network support for multimedia applications using the Netlets architecture

Multi-party multimedia networking applications such as e-commerce, distributed data analysis, Internet TV and advanced collaborative environments feature stringent end-to-end Quality of Service (QoS) requirement and require globally distributed user groups to be interconnected. The variety of delivery requirements posed by such applications are best satisfied using highly customised networking protocols. Hence, a demand for networks to migrate from the current fixed service model to a more flexible architecture that accommodates a wide variety of networking services is emerging. New approaches are required in order to build such service oriented networks. Active networking is one such approach. Active networks treats the network as a programmable computation engine, which provides customised packet processing and forwarding operations for traffic flowing through network nodes. User applications can download new protocols into network elements at runtime, allowing rapid innovation of network services. This thesis makes the case for employing mobile agents to realise an active networking architecture, and describes such an architecture called the Netlets architecture. Netlets are autonomous, mobile components which persist and roam in the network independently, providing predefined network services. This thesis presents the design and implementation of the Netlet node and the service deployment m echanisms that are required to distribute Netlet services in the network. Using the Netlet toolkit, variety of network services were designed to provide network support for multimedia applications in the Internet. A service was implemented to enhance the working of the RSVP protocol in order to provide robust end-to-end QoS support even when the network is only partially QoS provisioned. A scalable and reliable multicast protocol was implemented using the unicast communication model that accommodate heterogeneous receiver terminals. Another service integrates client-side server selection support into web sessions established over the Internet. A service was also developed which provides QoS signalling support to legacy applications. It is shown that these Netlet services are of practical value using performance measurements to assess Netlet responsiveness. Netlet based solutions maybe deployed using existing technologies to provide support for a wide range of multimedia applications in the Internet. The Netlets architecture has thus been shown to allow value-added services to be added to existing networks. By optimising the Netlet architecture implementation, this may be extended to services operating on high-speed (1Gb/s and upwards) links. It thus shows promise as an architecture for building the next generation of active networking solutions

A dynamic reconfiguration model of web services in service-oriented architecture

Service-Oriented Architecture (SOA) makes it possible to build distributed systems with web services that can be looked up, published and bound on the execution time across the boundary of an organisation over the Internet. By using standard interfaces and message-exchanging protocols, developers are able to reuse existing web services and integrate these individual services. Nevertheless, SOA must be able to provide a way to cope with dynamic changes that may occur in the system requirements and the environment in which the system operates. The means is known as dynamic reconfiguration that allows web services binding happens at runtime by matching the functional as well as Quality of Service (QoS) requirements to ensure dependable SOA systems. In the paper, we introduce a dynamic reconfiguration of web services model (DREWS) using middleware-based approach. The model intended to handle functional and QoS requirements during dynamic reconfiguration process and to provide an explicit mechanism during pre-, in-, and post-adaptation stages. A self-adaptive tool is developed based on the model to support the dynamic reconfiguration process that allows minimum human intervention

A Dynamic Reconfiguration Model of Web Services in Service-Oriented Architecture

Service-Oriented Architecture (SOA) makes it possible to build distributed systems with web services that can be looked up, published and bound on the execution time across the boundary of an organisation over the Internet. By using standard interfaces and message-exchanging protocols, developers are able to reuse existing web services and integrate these individual services. Nevertheless, SOA must be able to provide a way to cope with dynamic changes that may occur in the system requirements and the environment in which the system operates. The means is known as dynamic reconfiguration that allows web services binding happens at runtime by matching the functional as well as Quality of Service (QoS) requirements to ensure dependable SOA systems. In the paper, we introduce a dynamic reconfiguration of web services model (DREWS) using middleware-based approach. The model intended to handle functional and QoS requirements during dynamic reconfiguration process and to provide an explicit mechanism during pre-, in-, and post-adaptation stages. A selfadaptive tool is developed based on the model to support the dynamic reconfiguration process that allows minimum human intervention

GRIDCC: Real-time workflow system

The Grid is a concept which allows the sharing of resources between distributed communities, allowing each to progress towards potentially different goals. As adoption of the Grid increases so are the activities that people wish to conduct through it. The GRIDCC project is a European Union funded project addressing the issues of integrating instruments into the Grid. This increases the requirement of workflows and Quality of Service upon these workflows as many of these instruments have real-time requirements. In this paper we present the workflow management service within the GRIDCC project which is tasked with optimising the workflows and ensuring that they meet the pre-defined QoS requirements specified upon them

Challenges to describe QoS requirements for web services quality prediction to support web services interoperability in electronic commerce

Quality of service (QoS) is significant and necessary for web service applications quality assurance. Furthermore, web services quality has contributed to the successful implementation of Electronic Commerce (EC) applications. However, QoS is still the big issue for web services research and remains one of the main research questions that need to be explored. We believe that QoS should not only be measured but should also be predicted during the development and implementation stages. However, there are challenges and constraints to determine and choose QoS requirements for high quality web services. Therefore, this paper highlights the challenges for the QoS requirements prediction as they are not easy to identify. Moreover, there are many different perspectives and purposes of web services, and various prediction techniques to describe QoS requirements. Additionally, the paper introduces a metamodel as a concept of what makes a good web service