The use of service-oriented (SO) distributed systems is increasing. Within service orientation web services (WS) are the de facto standard for implementing service-oriented systems. The consumers of WS want to get uninterrupted and reliable service from the service providers. But WS providers cannot always provide services in the expected level due to faults and failures in the system. As a result the fault management of these systems is becoming crucial. This work presents a distributed event-driven architecture for fault management of Web Services. According to the architecture the managed WS report different events to the event databases. From event databases these events are sent to the event processors. The event processors are distributed over the network. They process the events, detect fault scenarios in the event stream and manage faults in the WS.

This research explores the problems associated with caching of SOAP Web Service request/response pairs, and presents a domain independent framework enabling transparent caching of Web Service requests for mobile clients. The framework intercepts method calls intended for the web service and proceeds by buffering and caching of the outgoing method call and the inbound responses. This enables a mobile application to seamlessly use Web Services by masking fluctuations in network conditions. This framework addresses two main issues, firstly how to enrich the WS standards to enable caching and secondly how to maintain consistency for state dependent Web Service request/response pairs.

Orchestrated web service applications are highly distributed applications that accomplish business goals by executing services offered by partners. This dependance on partner services allows the development of more flexible, modular applications. For a classical distributed system, correctness can be ensured by statically checking the composition of the components that make up the system against properties of interest. However, in the case of web service applications, there are various conditions that make this type of analysis insufficient. For example, partners can be dynamically discovered, which means that we cannot create a definitive model of the system to analyze. Web service applications can also display new behaviour at execution time, so statically checked properties of the system may not hold throughout the system's lifetime. Due to these limitations of static analysis, this thesis concentrates on the dynamic analysis of web service applications, specifically, by monitoring runtime events. The goal of runtime monitoring is to check whether an application violates a given specification of its behaviour during its execution. The behaviour of the system can be specified in a number of ways, e.g., as a set of temporal properties, assertions or even scenarios. During execution, application events are intercepted and used to determine if the system is violating its specification. Moreover, monitoring the system as it runs provides a chance to recover from an error once a problem has been detected. This is critical in the domain of web service applications, as bugs are potentially exposed to millions of users before they are found/fixed. We present techniques to address several major challenges facing the creation of an industrial-strength runtime monitoring and recovery framework for web service applications. The first milestone for achieving this goal is the creation of an adequate property specification language. This language must be expressive enough to capture the distributed, interactive, and message-driven nature of web service applications, but must also be amenable to efficient runtime monitoring. We propose Web Sequence Diagrams (W-SD), a language that, we feel, meets these criteria. Specifications expressed in W-SD permit the analysis of orchestrations involving multiple partners, from the point of view of the orchestrating service. The second contribution of this thesis is the creation of an industrial-strength online runtime monitoring and recovery framework that is non-intrusive, supports the dynamic discovery of web services, deals with synchronous and asynchronous communication, as well as partner services implemented in different languages. Developers using this framework can specify and efficiently monitor a variety of temporal behaviour. If recovery is enabled, properties are monitored proactively, so this framework allows developers to effortlessly enable error recovery in applications being monitored. The last contribution of this thesis is the development of recovery plans from runtime errors. Given an application path which led to a failure and a monitor which detected it, we have developed various techniques and optimizations that make recovery plan generation feasible in practice. For some of the violations, such plans essentially involve "going back" -- compensating the occurred actions until an alternative behaviour of the application is possible. For other violations, such plans include both "going back" and "re-planning" -- guiding the application towards a desired behaviour.

Mobile devices have evolved over the years from resource constrained devices that supported only the most basic tasks to powerful handheld computing devices. However, the most significant step in the evolution of mobile devices was the introduction of wireless connectivity which enabled them to host applications that require internet connectivity such as email, web browsers and maybe most importantly smart/rich clients. Being able to host smart clients allows the users of mobile devices to seamlessly access the Information Technology (IT) resources of their organizations. <p>One increasingly popular way of enabling access to IT resources is by using Web Services (WS). This trend has been aided by the rapid availability of WS packages/tools, most notably the efforts of the Apache group and Integrated Development Environment (IDE) vendors. But the widespread use of WS raises questions for users of mobile devices such as laptops or PDAs; how and if they can participate in WS. Unlike their wired counterparts (desktop computers and servers) they rely on a wireless network that is characterized by low bandwidth and unreliable connectivity.<p>The aim of this thesis is to enable mobile devices to host Web Services consumers. It introduces a Model-Driven Dual Caching (MDDC) approach to overcome problems arising from temporarily loss of connectivity and fluctuations in bandwidth.

In the Service Oriented Architecture (SOA) services are computational elements that are published, discovered, consumed and aggregated across platform and organizational borders. The most commonly used technology to achieve SOA are Web Services (WSs). This is due to standardization process (WSDL, SOAP, UDDI standards) and a wide range of available infrastructure and tools. A very interesting aspect of WSs is their composeability. WSs can be easily aggregated into complex workflows, called Composite Web Services (CWSs). These compositions of services enable further reuse and in this way new, even more complex, systems are built.<p>Although there are many languages to specify or implement workflows, in the service-oriented systems BPEL (Business Process Execution Language) is widely accepted. With this language WSs are orchestrated and then executed with specialized engines (like ActiveBPEL). While being very popular, BPEL has certain limitations in monitoring and optimizing executions of CWSs. It is very hard with this language to adapt CWSs to changes in the performance of used WSs, and also to select the optimal way to execute a CWS. <p>To overcome the limitations of BPEL, I present a model-aware approach to execute CWSs. To achieve the model awareness the Coloured Petri Nets (CPN) formalism is considered as the basis of the execution of CWSs. This is different than other works in using formal methods in CWSs, which are restricted to purposes like verification or checking of correctness. Here the formal and unambiguous notation of the CPN is used to model, analyze, execute and monitor CWSs. Furthermore this approach to execute CWSs, which is based on the CPN formalism, is implemented in the model-aware middleware. It is also demonstrated how the middleware improves the performance and reliability of CWSs.

Orchestrated web service applications are highly distributed applications that accomplish business goals by executing services offered by partners. This dependance on partner services allows the development of more flexible, modular applications. For a classical distributed system, correctness can be ensured by statically checking the composition of the components that make up the system against properties of interest. However, in the case of web service applications, there are various conditions that make this type of analysis insufficient. For example, partners can be dynamically discovered, which means that we cannot create a definitive model of the system to analyze. Web service applications can also display new behaviour at execution time, so statically checked properties of the system may not hold throughout the system's lifetime. Due to these limitations of static analysis, this thesis concentrates on the dynamic analysis of web service applications, specifically, by monitoring runtime events. The goal of runtime monitoring is to check whether an application violates a given specification of its behaviour during its execution. The behaviour of the system can be specified in a number of ways, e.g., as a set of temporal properties, assertions or even scenarios. During execution, application events are intercepted and used to determine if the system is violating its specification. Moreover, monitoring the system as it runs provides a chance to recover from an error once a problem has been detected. This is critical in the domain of web service applications, as bugs are potentially exposed to millions of users before they are found/fixed. We present techniques to address several major challenges facing the creation of an industrial-strength runtime monitoring and recovery framework for web service applications. The first milestone for achieving this goal is the creation of an adequate property specification language. This language must be expressive enough to capture the distributed, interactive, and message-driven nature of web service applications, but must also be amenable to efficient runtime monitoring. We propose Web Sequence Diagrams (W-SD), a language that, we feel, meets these criteria. Specifications expressed in W-SD permit the analysis of orchestrations involving multiple partners, from the point of view of the orchestrating service. The second contribution of this thesis is the creation of an industrial-strength online runtime monitoring and recovery framework that is non-intrusive, supports the dynamic discovery of web services, deals with synchronous and asynchronous communication, as well as partner services implemented in different languages. Developers using this framework can specify and efficiently monitor a variety of temporal behaviour. If recovery is enabled, properties are monitored proactively, so this framework allows developers to effortlessly enable error recovery in applications being monitored. The last contribution of this thesis is the development of recovery plans from runtime errors. Given an application path which led to a failure and a monitor which detected it, we have developed various techniques and optimizations that make recovery plan generation feasible in practice. For some of the violations, such plans essentially involve "going back" -- compensating the occurred actions until an alternative behaviour of the application is possible. For other violations, such plans include both "going back" and "re-planning" -- guiding the application towards a desired behaviour.

Sensor network web services have recently emerged as promising tools to provide remote management, data collection and querying capabilities for sensor networks. They can be utilized in a large number of elds among which Demand-Side Energy Management (DSEM) is an important application area that has become possible with the smart electrical power grid. DSEM applications generally aim to reduce the cost and the amount of power consumption. In the traditional power grid, DSEM has not been implemented widely due to the large number of households and lack of ne-grained automation tools. However by employing intelligent devices and implementing communication infrastructure among these devices, the smart grid will renovate the existing power grid and it will enable a wide variety of DSEM applications. In this thesis, we analyze various DSEM scenarios that become available with sensor network web services. We assume a smart home with a Wireless Sensor Network (WSN) where the sensors are mounted on the appliances and they are able to run web services. The web server retrieves data from the appliances via the web services running on the sensor nodes. These data can be stored in a database after processing, where the database can be accessed by the utility, as well as the inhabitants of the smart home. We showthat our implementation is e cient in terms of running time. Moreover, the message sizes and the implementation code is quite small which makes it suitable for the memory-limited sensor nodes. Furthermore, we show the application scenarios introduced in the thesis provide energy saving for the smart home.

Existing QoS-aware Web Services discovery architectures tend to focus solely on fulfilling the requirements of either the client or the provider. However, the interests of the provider and client are not equivalent. The provider’s goal is to maximize the profit and consume the least amount of resources. On the other hand, the client’s selection is determined by their own requirements which do not always reflect the real resource overheads. This research aims to provide a novel mobile Web Services discovery and selection method based on utility functions to balance the requirements for clients and providers. In the mobile environment, it is critical to conserve resource consumption in addition to fulfilling user requirements, as resources such as wireless network bandwidth and mobile device power are precious. The proposed service selection strategy enables service providers to balance the cost/performance ratios and utilize the network bandwidth more effectively, while the clients can still attain the functional and quality levels specified in the service request.

Los sistemas de información construidos mediante servicios distribuidos basados en estándares se han convertido en el paradigma de computación adoptado por defecto por la comunidad geoespacial para la construcción de infraestructuras de información. Diferentes disposiciones gubernamentales, como la Directiva Europea INSPIRE, recomiendan normas para compartir recursos (por ejemplo, datos y procesos) con el objetivo de mejorar el estudio del medio ambiente (y otros campos similares) y la toma de decisiones.La mayoría de las infraestructuras de información geoespacial (IIG) atienden necesidades básicas tales como acceso a datos, visualización y descarga, sin embargo, tienen escasos enlaces a servicios de geoprocesamiento. Además, la mayorí¬a de infraestructuras geoespaciales se han construido siguiendo un enfoque del tipo top-down, donde sólo a los proveedores oficiales (por lo general los organismos públicos) se les permite desplegar y mantener recursos. Debido a que los mecanismos para desplegar e integrar recursos en estas infraestructuras son tecnológicamente complejos, existe una muy limitada participación por parte de los usuarios, provocando a la larga la escasez de recursos actualizados.Para hacer frente a estas limitaciones, se presenta en este trabajo, una arquitectura distribuida basada en los principios de INSPIRE y ampliada con un componente llamado ServiceFramework. Este componente proporciona capacidad de procesamiento, ofreciendo una funcionalidad existente en forma de servicio estándar de procesamiento. También mejora la integración ad hoc y el despliegue de recursos de información geoespacial dentro de la infraestructura. El ServiceFramework trata la necesidad de mejorar la disponibilidad de recursos de datos geoespaciales, proporcionando mecanismos para generar de forma automática servicios compatible con INSPIRE.Estas contribuciones son evaluadas en dos escenarios diferentes dentro de dos proyectos europeos. En el proyecto AWARE, se demuestra cómo un grupo de hidrólogos puede beneficiarse del acceso a las infraestructuras geoespaciales donde pueden compartir capacidades de procesamiento. En el proyecto EuroGEOSS, demostramos cómo mejorar la disponibilidad de los recursos geoespaciales para analizar un escenario forestal. Se prevé que estas nuevas metodologí¬as, pueden aumentar la participación de usuarios más expertos en la creación de infraestructuras de información geoespacial, lo que aumenta la utilidad y el valor de estas infraestructuras.

Existing QoS-aware Web Services discovery architectures tend to focus solely on fulfilling the requirements of either the client or the provider. However, the interests of the provider and client are not equivalent. The provider’s goal is to maximize the profit and consume the least amount of resources. On the other hand, the client’s selection is determined by their own requirements which do not always reflect the real resource overheads. This research aims to provide a novel mobile Web Services discovery and selection method based on utility functions to balance the requirements for clients and providers. In the mobile environment, it is critical to conserve resource consumption in addition to fulfilling user requirements, as resources such as wireless network bandwidth and mobile device power are precious. The proposed service selection strategy enables service providers to balance the cost/performance ratios and utilize the network bandwidth more effectively, while the clients can still attain the functional and quality levels specified in the service request.