1. A computer system for controlling a workflow process, comprising: a process modelling unit configured to define a process model with at least a first task and a second task, wherein the second task needs to comply with a control aspect and depends on the first task, and further configured to insert into the process model a control task between the first and the second task, wherein the control task is configured to enforce the control aspect on the second task by using a control service of a subsystem; and a process execution unit configured to generate a process instance from the process model and to instantiate a control context to capture the current state of the process instance, the control context being used by an instance of the control task to invoke the control service according to the control aspect.