Increasing Availability of Workflows Executing in a Pervasive Environment

Workflows have gained enormous importance to organize and manage business processes. With the recent advent of smartphones and mobile applications, traditional business process management is shifting. Now, long-running business processes (workflows) have to be executed in large-scale distributed and pervasive environments. Due to the heterogeneity and high dynamicity of such environments, they are vulnerable to frequent communication and device failures and, thus, impose new requirements on the execution of workflows. To increase the availability, we concurrently executed restructured replicas of workflows on multiple nodes. We developed techniques to generate differently structured replicas and propose a metric that identifies the set of replicas that ensures the highest availability during execution. Finally, we presented a distributed algorithm to coordinate and synchronize the concurrent execution of the identified replicas while maintaining the original workflow semantics. Our methods approximately double the availability during execution, while our generation techniques produce almost optimal replicas over a hundred times faster.