Constraint integration and violation handling for BPEL processes

Autonomic, i.e. dynamic and fault-tolerant Web service composition is a requirement resulting from recent developments such as on-demand services. In the context of planning-based service composition, multi-agent planning and dynamic error handling are still unresolved problems. Recently, business rule and constraint management has been looked at for enterprise SOA to add business flexibility. This paper proposes a constraint integration and violation handling technique for dynamic service composition. Higher degrees of reliability and fault-tolerance, but also performance for autonomously composed WS-BPEL processes are the objectives

State-preserving container orchestration in failover scenarios

Containers have been widely adopted for deployment of high availability applications and services. This adoption is in part due to the native support of fault tolerance mechanisms in container orchestration frameworks such as Kubernetes. While Kubernetes provides service replication as a fault tolerance mechanism for stateless applications, service replication does not satisfy requirements for stateful applications. Currently this shortcoming is addressed by data replication in databases. This requires a tight coupling and modification of the stateful application to support high availability. Thus, this thesis proposes a new Checkpoint/Restore (C/R) Kubernetes operator to achieve fault tolerance for stateful applications without any modification of the application. The operator takes a checkpoint in a configurable interval. In case of a fault a new application container is created automatically from the most recent checkpoint. We compare the proposed approach with a more conventional approach in which we pull and restore the application state from the application through an API. We measure the overhead of both methods, the service interruption and the recovery time in case of faults. We find the C/R Operator has similar performance in recovery time as the traditional approach, but does not need any application modification. The results signify C/R as a promising technology for a fault tolerance mechanism for stateful applications

Fault Tolerance Using an SDN Pattern Framework

Software Defined Networking (SDN) and Network Function Virtualization (NFV) are a promising combination for programmable connectivity, rapid service provisioning and service chaining as they offer the necessary end-to-end optimizations. However, with the actual exponential growth of connected devices, future networks such as SDN/NFV require an open-solutions architecture, facilitated by standards and a strong ecosystem. Such networks need to support communication services that offers guarantees about fault tolerance, redundancy, resilience and security. The construction of complex networks preserving Security and Dependability (S&D) properties is necessary to avoid system vulnerabilities, which may occur in the various layers of SDN architectures. In this work, we propose a pattern framework build in an SDN controller able to import design patterns in a rule-based language in order to provide fault tolerance in SDN networks. To evaluate the importance and the functionality of this framework, fault tolerance patterns are proposed to guarantee network connectivity, detection and restoration of network traffic in SDN network infrastructures

A Multi-Objective Optimization Approach for Fault-Tolerance Provisioning in Multi-Radio Hybrid Wireless-Optical Broadband Access Networks

Wireless-optical broadband-access networks (WOBANs), currently being deployed at the access section, should integrate fault-tolerance in their design so that geographically continuous wireless coverage can be provided without service breaks. In this paper we propose a joint wireless and optical fault-tolerance planning approach for WOBANs having multiple radios in each router. The problem is formalized, as a multi-objective optimization problem, and a heuristic is proposed to solve this problem. Two fault-tolerance planning scenarios, where gateways are arranged differently in the risk groups, are analysed. It is shown that multi-radio routers can be exploited to improve the performance of WOBANs, providing wireless and optical fault-tolerance. Results also indicate that, when using our approach, a small increase in the number of radios can significantly decrease the total capacity required to provide any degree of fault-tolerance.This work was supported by the Foundation for Science and Technology from Portugal within CEOT (Center for Electronic, Optoelectronic and Telecommunications) and by the project PTDC/EEA-TEL/71678/2006

A fault fuzzy-ontology for large scale fault-tolerant wireless sensor networks

International audienceFault tolerance is a key research area for many of applications such as those based on sensor network technologies. In a large scale wireless sensor network (WSN), it becomes important to find new methods for fault-tolerance that can meet new application requirements like Internet of things, urbane intelligence and observation systems. The challenge is beyond the limit of a single wireless sensor network and concerns multiple widely interconnected sub networks. The domain of fault grows considerably because of this new configuration. In this context, the paper proposes a fault fuzzy-ontology (FFO) for large scale WSNs to be used within a Web service architecture for diagnosis and testing