Improving reliability of service oriented systems with consideration of cost and time constraints in clouds

Web service technology is more and more popular for the implementation of service oriented systems. Additionally, cloud computing platforms, as an efficient and available environment, can provide the computing, networking and storage resources in order to decrease the budget of companies to deploy and manage their systems. Therefore, more service oriented systems are migrated and deployed in clouds. However, these applications need to be improved in terms of reliability, for certain components have low reliability. Fault tolerance approaches can improve software reliability. However, more redundant units are required, which increases the cost and the execution time of the entire system. Therefore, a migration and deployment framework with fault tolerance approaches with the consideration of global constraints in terms of cost and execution time may be needed. This work proposes a migration and deployment framework to guide the designers of service oriented systems in order to improve the reliability under global constraints in clouds. A multilevel redundancy allocation model is adopted for the framework to assign redundant units to the structure of systems with fault tolerance approaches. An improved genetic algorithm is utilised for the generation of the migration plan that takes the execution time of systems and the cost constraints into consideration. Fault tolerant approaches (such as NVP, RB and Parallel) can be integrated into the framework so as to improve the reliability of the components at the bottom level. Additionally, a new encoding mechanism based on linked lists is proposed to improve the performance of the genetic algorithm in order to reduce the movement of redundant units in the model. The experiments compare the performance of encoding mechanisms and the model integrated with different fault tolerance approaches. The empirical studies show that the proposed framework, with a multilevel redundancy allocation model integrated with the fault tolerance approaches, can generate migration plans for service oriented systems in clouds with the consideration of cost and execution time

Security Engineering of SOA Applications Via Reliability Patterns

Providing reliable compositions of Web Services is a challenging issue since the workflow architect often has only a limited control over the reliability of the composed services. The architect can instead achieve reliability by properly planning the workflow architecture. To this end he must be able to evaluate and compare the reliability of multiple architectural solutions. In this paper we present a useful tool which allows to conduct reliability analysis on planned workflows, as well as to compare the reliability of alternative solutions in a what-if analysis. The tool is implemented as a plug-in for the widely adopted Active BPEL Designer and exploits the concept of reliability pattern to evaluate the reliability formula of the workflow. The effectiveness of the approach and the operation of the tool are demonstrated with respect to a case study of a business security infrastructure realized by orchestrating simple security services

Security Engineering of SOA Applications Via Reliability Patterns

Providing reliable compositions of Web Services is a challenging issue since the workflow architect often has only a limited control over the reliability of the composed services. The architect can instead achieve reliability by properly planning the workflow architecture. To this end he must be able to evaluate and compare the reliability of multiple architectural solutions. In this paper we present a useful tool which allows to conduct reliability analysis on planned workflows, as well as to compare the reliability of alternative solutions in a what-if analysis. The tool is implemented as a plug-in for the widely adopted Active BPEL Designer and exploits the concept of reliability pattern to evaluate the reliability formula of the workflow. The effectiveness of the approach and the operation of the tool are demonstrated with respect to a case study of a business security infrastructure realized by orchestrating simple security services