Disclosed is apparatus for processing business data processing activities, the apparatus comprising: an activity instance; and a descriptor for the activity instance associated uniquely with the activity instance; wherein the descriptor includes parameters for determining lifecycle behaviors of said activity instance. The descriptor may be programmable to modify the lifecycle behaviors according to a use made of said activity instance. The use of the activity instance may be responsive to a request by a client. It may also be responsive to a request by an activity instance. The descriptor may be programmable to modify the lifecycle behaviors according to a position in a system hierarchy of the activity instance.