Fault-Tolerant BPEL Workflow Execution via Cloud-Aware Recovery Policies

BPEL is the de facto standard for business process modeling in today's enterprises and is a promising candidate for the integration of business and scientific applications that run in Grid or Cloud environments. In these distributed infrastructures, the occurrence of faults is quite likely. Without sophisticated fault handling, workflows are frequently abandoned due to software or hardware failures, leading to a waste of CPU hours. The fault handling mechanisms provided by BPEL are well suited for handling faults of the business logic, but infrastructure-induced errors should be handled automatically to avoid over-complication of workflow design and keep concerns separated. This paper identifies classes of faults that can be resolved automatically by the infrastructure, and provides a policy-based approach to configure this automatic behavior without the need for adding explicit fault handling mechanisms to the BPEL process. The proposed approach provides automatic redundancy of services using a Cloud infrastructure to allow substitution of defective services. An implementation based on the ActiveBPEL engine and Amazon's Elastic Compute Cloud is presented.