Maintaining Transactional Integrity in Long Running Workflow Services

Abstract

This chapter presents a framework to provide autonomous handling of long running transactions based on dependencies which are derived from the workflow. Business Processes naturally involve long running activities and require transactional behaviour across them. This framework presents a solution for forward recovery from errors by automatic application of compensation to executing instances of workflows. The mechanism is based on propagation of failures through a recursive hierarchical structure of transaction components (nodes and execution paths). The authors discuss a transaction management system that is implemented as a reactive system controller, where system components change their states based on rules in response to triggering of events, such as activation, failure, force-fail, completion, or compensation events. One notable feature of the model is the distinction of vital and non-vital components, allowing the process designer to express the cruciality of activities in the workflow with respect to the business logic. Another novel feature is that in addition to dependencies arising from the structure of the workflow, the approach also permits the workflow designer to specify additional dependencies which will also be enforced. Thus, the authors introduce new techniques and architectures supporting enterprise integration solutions that cater to the dynamics of business needs. The approach is implemented through workflow actions executed by services and allows management of faults through a policy-driven framework.