Dependability in the Web Service Architecture

2007 Latin American Web Conference (LA-WEB 2007), 2007

Web services have been pointed as a suitable technology for the development and execution of distributed applications. However, the Web service architecture still lacks facilities to support fault tolerance. The goal of this paper is to propose a fault tolerant Web service architecture. The architecture provides service mediation and monitoring. The main contribution of this paper is the use of Web service standards to include fault tolerance in the Web service architecture.

Proceedings of the 2007 Workshop on Engineering Fault Tolerant Systems, EFTS '07, 2007

Many businesses are now moving towards the use of composite web services that are based on a collection of web services working together to achieve an objective. Although they are becoming business-critical elements, current development support tools do not provide a practical way to include fault tolerance characteristics in web services compositions. This paper proposes a mechanism that allows programmers to easily develop fault tolerant compositions using diverse web services. The mechanism allows programmers to specify alternative web services for each operation and offers a set of artifacts that simplify the coding process, by automatically dealing with all the aspects related to the redundant web services invocation and responses voting. The mechanism is also able to perform a continuous evaluation of the services based on their behavior during operation. The approach is illustrated using compositions based on web services publicly available in the Internet and on the web services specified by the standard TPC-App performance benchmark.

Proceedings of the 2008 ACM symposium on Applied computing - SAC '08, 2008

Web services have been widely employed to allow interoperability among applications and/or technologies. However, the standard technologies and protocols which provide the foundation for Web Services do not address issues such as fault tolerance and dependability of services. Aiming to solve this limitation, this paper proposes a software architecture for providing dependability for Web Services. This architecture is responsible for increasing service availability and maintaining all replicas of a service in a consistent state, having as main characteristic the separation of these replicas in groups.

2002

The Web services platform offers a distributed computing environment where autonomous applications interact using standard Internet technology. In this environment, diverse applications and systems become the components of intraand inter-enterprise integration. Yet, transactional reliability, an often critical requirement on such integration, is presently missing from the Web services platform. In this paper, we address this shortcoming and propose the WSTx framework as an approach to Web service reliability. WSTx introduces transactional attitudes to explicitly describe the otherwise implicit transactional semantics, capabilities, and requirements of individual applications. We show how explicit transactional attitude descriptions can be used by a middleware system to automate the reliable composition of applications into larger Web transactions, while maintaining autonomy of the individual applications.

A major area of recent web-related research concerns automated web service composition. Complex services may be dynamically composed through combining distributed components. In Web services, standard communication protocols and simple broker-request architectures are needed to facilitate exchange of services, and this standardization simplifies interoperability. A major advantage of web services technology lies in the potential of creating value-added services by combining existing ones to achieve customized tasks. How to combine these services efficiently into an arrangement that is both functionally sound and architecturally realizable is a very challenging topic that has founded a significant research area within computer science. Our research contribution lies in the area of dynamic composition services selection. We have started by collating and analyzing current outstanding problems within the dynamic composition area. To help explain the background to these challenges we compare, firstly, the key components of distributed computing technologies with web service composition. Then we define the 'execute ability' problem – the key idea that preconditions of web services must be satisfied before or as a result of composition. In order to enable semantics-based dynamic service composition, this paper analyzes relative service composition mechanism. Then it proposes a dynamic composition service framework based on semantic and implements its key technology. These techniques can bring flexibility and adaptability to future application. We discuss data distribution strategies among services, how they can be used to overcome problems in dynamic composition problems and how they relate to the quality of service. Finally, we present our proposed framework model to handle the process of web service composition and execution. We propose that this framework eliminates the main problems as discussed in the paper.

Transactional business processes require a high degree of reliability in order to guarantee consistent results. In case of failure, participants must take the necessary actions to leave the process in a globally-correct state. Conventional Web services, however, frequently lack essential reliability features. Based on the Web Services Transactions specifications, we present a framework that provides fault tolerance to the services involved in a transactional business process, leveraging techniques in logical logging and application recovery. In contrast to current implementations, it aims to minimize the impact on existing applications with regards to performance and code changes. This work is part of the METEOR-S project at the Large Scale Distributed Information Systems (LSDIS) lab at The University of Georgia.

International Conference on Web Engineering, 2006

Reliability is one of the main challenge that encounter Web services compositions. Due to the inherent autonomy and heterogeneity of Web services it is difficult to predict the behavior of the overall composite service.

2006

The interest surrounding the Web services (WS) composition issue has been growing tremendously. In the near future, it is awaited to prompt a veritable shift in the distributed computing history, by making the Service-Oriented Architecture (SOA) a reality. Yet, the way ahead is still long. A careful investigation of a major part of the solutions proposed so far reveals that they follow a workflow-like composition approach and that they view failures as exceptional situations that need not to be a primary concern. In this paper, we claim that obeying these assumptions in the WS realm may constrain critically the chances to achieve a high-dependability level and may hamper significantly flexibility. Motivated with these arguments, we propose a WS composition modeling approach that accepts failures inevitability and enriches the composition with concepts that can add flexibility and dependability but that are not part from the WS architecture pillars, namely, the state, the transactional behavior, the vitality degree, and the failure recovery. In addition, we describe a WS composition in terms of definition rules, composability rules, and ordering rules, and we introduce a graphical and a formal notation to ensure that a WS composition is easily and dynamically adaptable to best suit the requirements of a continuously changing environment. Our approach can be seen as a higher level of abstraction of many of the current solutions, since it extends them with the required support to achieve higher flexibility, dependability, and expressiveness power.

World Wide Web Conference Series, 2005

The recent evolution of Internet, driven by the Web services technology, is extending the role of the Web from a support of information interaction to a middleware for B2B interactions.

2006 IEEE International Conference on Web Services (ICWS'06), 2006

Current Web services composition approaches do not take into account transactional requirements defined by designers. The transactional challenges raised by the composition of Web services are twofold: relaxed atomicity and dynamicity. In this paper, we propose a new process to automate the design of transactional composite Web services. Our solution enables the composition of Web services not only according to functional requirements but also to transactional ones defined using the Acceptable Termination States model. The resulting composite Web service is compliant with the consistency requirements expressed by designers and its execution can easily be coordinated using the coordination rules provided as an outcome of our approach.