Message routing can take different series of processing steps. In Routing Slip pattern message contains the routing path (a sequence of processing steps) which is decided at design stage. But in many cases the routing decisions have to be made based on intermediate results and processing steps may need to execute in parallel. In order to achieve that dynamic behaviour this pattern introduce a processing unit called Process Manager, which determines the next processing step based on the intermediate results.
Designing and configure a Process Manager is an extensive area and WSO2 has done implementing patterns related to design of workflow or Business Process Management. WSO2 Business Process Server enables user to easily develop business processes with WS-BPEL standard and provide hosting environment.