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

Employing performance counters and software wrapper for measuring QoS attributes of web services

Web services have got popular for developing Service-Oriented Architectures recently. As several web services are available to execute the same function, Quality of Service (QoS) turns into a discriminative factor which is significantly considered in service selection and service composition approaches. In different approaches, monitoring of services is used for evaluating QoS attributes. Custom Windows Performance Counters (CWPC) is one of the approaches for monitoring performance of services at server-side. However, it has some limitations and it needs to access and change a service implementation which is not always possible in practice. In this paper, CWPC along with software wrapper is employed for measuring different QoS attributes such as response time, throughput and reliability in order to overcome current limitations. Additionally, it discusses how the proposed monitoring mechanism can be employed to optimize the service provider performance. The results show that the proposed monitoring approach is accurate in measuring QoS attributes

Verkkojärjestelmien seurantatyökalujen kehittäminen

With increasing amounts of software services provided to users and the more demanding requirements needed from them, monitoring of services is becoming increasingly important. Web service monitoring is the process of confirming system functionality by studying its various attributes, such as availability, reliability, and performance. Monitoring the services helps the software developers, maintainers and owners as they allow for increased reliability, robustness and possibly performance analysis. This thesis focuses on web service monitoring and the tools that it is done with. Specific goals are to learn about the different categories that monitoring services can take and to showcase a custom web service monitoring tool and its further development. The subject is important to the case company LogiNets, which has specific monitoring requirements that need to be fulfilled. These goals were achieved by researching literature on different types of monitoring tools for a literature review and then doing a case study of monitoring tool development. The case study was done about adding a new functionality to LogiNets’s indoor web service monitoring tool called Agent. The literature review was successful in identifying different categories of monitoring tools both by their location relative to the monitored service as well as by the quality of service requirements they fulfill. The review did not, however, discover significant research about existing commercial monitoring tools, and thus provided little help in the case study. The case study was more successful, with the new functionality added and similar extensions planned for the future

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

Service adaptation with probabilistic partial models

Web service composition makes use of existing Web services to build complex business processes. Non-functional requirements are crucial for the Web service composition. In order to satisfy non-functional requirements when composing a Web service, one needs to rely on the estimated quality of the component services. However, estimation is seldom accurate especially in the dynamic environment. Hence, we propose a framework, ADFlow, to monitor and adapt the workflow of the Web service composition when necessary to maximize its ability to satisfy the non-functional requirements automatically. To reduce the monitoring overhead, ADFlow relies on asynchronous monitoring. ADFlow has been implemented and the evaluation has shown the effectiveness and efficiency of our approach. Given a composite service, ADFlow achieves 25 %–32 % of average improvement in the conformance of non-functional requirements, and only incurs 1 %–3 % of overhead with respect to the execution time.No Full Tex

A trust and reputation model based on bayesian network for web services

Trust and reputation for web services emerges as an important research issue in web service selection. Current web service trust models either do not integrate different important sources of trust (subjective and objective for example), or do not focus on satisfying different user’s requirements about different quality of service (QoS) attributes such as performance, availability etc. In this paper, we propose a Bayesian network trust and reputation model for web services that can overcome such limitations by considering several factors when assessing web services’ trust: direct opinion from the truster, user rating (subjective view) and QoS monitoring information (objective view). Our comprehensive approach also addresses the problems of users’ preferences and multiple QoSbased trust by specifying different conditions for the Bayesian network and targets at building a reasonable credibility model for the raters of web services

Global-Scale Resource Survey and Performance Monitoring of Public OGC Web Map Services

One of the most widely-implemented service standards provided by the Open Geospatial Consortium (OGC) to the user community is the Web Map Service (WMS). WMS is widely employed globally, but there is limited knowledge of the global distribution, adoption status or the service quality of these online WMS resources. To fill this void, we investigated global WMSs resources and performed distributed performance monitoring of these services. This paper explicates a distributed monitoring framework that was used to monitor 46,296 WMSs continuously for over one year and a crawling method to discover these WMSs. We analyzed server locations, provider types, themes, the spatiotemporal coverage of map layers and the service versions for 41,703 valid WMSs. Furthermore, we appraised the stability and performance of basic operations for 1210 selected WMSs (i.e., GetCapabilities and GetMap). We discuss the major reasons for request errors and performance issues, as well as the relationship between service response times and the spatiotemporal distribution of client monitoring sites. This paper will help service providers, end users and developers of standards to grasp the status of global WMS resources, as well as to understand the adoption status of OGC standards. The conclusions drawn in this paper can benefit geospatial resource discovery, service performance evaluation and guide service performance improvements.Comment: 24 pages; 15 figure

BioCatalogue: a universal catalogue of web services for the life sciences

The use of Web Services to enable programmatic access to on-line bioinformatics is becoming increasingly important in the Life Sciences. However, their number, distribution and the variable quality of their documentation can make their discovery and subsequent use difficult. A Web Services registry with information on available services will help to bring together service providers and their users. The BioCatalogue (http://www.biocatalogue.org/) provides a common interface for registering, browsing and annotating Web Services to the Life Science community. Services in the BioCatalogue can be described and searched in multiple ways based upon their technical types, bioinformatics categories, user tags, service providers or data inputs and outputs. They are also subject to constant monitoring, allowing the identification of service problems and changes and the filtering-out of unavailable or unreliable resources. The system is accessible via a human-readable ‘Web 2.0’-style interface and a programmatic Web Service interface. The BioCatalogue follows a community approach in which all services can be registered, browsed and incrementally documented with annotations by any member of the scientific community

SALMon: A SOA system for monitoring service level agreements

In this paper we present SALMon, a tool assessing the satisfaction of service level agreement (SLA) clauses by service-oriented systems. SALMon itself is organized as a service-oriented system that offers two kind of services: 1) the Monitor service that measures the values in execution time of dynamic quality attributes (like response time or availability), and 2) the Analyzer service that detects and reports violations of SLA clauses from the values obtained with the Monitor. The SALMon tool is highly versatile, allowing: 1) both active testing and passive monitoring as strategies, 2) different types of technologies for the monitored/tested systems (e.g., Web services, RESTful services), 3) agile definition of measure instruments for new quality attributes. The service-oriented nature of SALMon makes it scalable and easy to integrate with other services that need its functionalities.Postprint (published version

iiWAS - Towards Context-Based Tracking of Web Services Security.

With the increasing popularity of Web services and increasing complexity of users\u27 needs, there has been a renewed interest in Web services composition. However, composition faces a major obstacle, which is the content heterogeneity of the contexts featuring the component Web services of a composite service. An unawareness or poor consideration of this heterogeneity during Web services composition and execution definitely results in a lack of the quality and relevancy of information that is deemed appropriate for tracking the composition, monitoring the execution, and handling exceptions. An earlier paper had provided a 3-level approach for content reconciliation of Web services\u27 contexts using ontologies. This paper extends the 3-level approach by focusing on the security breaches that threaten the integrity of the context of Web services, and proposes appropriate means to achieve this integrity