What is Workflow Broker

This chapter describes the error recovery mechanisms in the system handling the Grid-based workflow within the Service Level Agreement (SLA) context. It classifies the errors into two main categories. The first is the large-scale errors when one or several Grid sites are detached from the Grid system at a time. The second is the small-scale errors which may happen inside an RMS. For each type of error, the chapter introduces a recovery mechanism with the SLA context imposing the goal to the mechanisms. The authors believe that it is very useful to have an error recovery framework to avoid or eliminate the negative effects of the errors.