A workflow server can receive requests, each for a business process workflow conforming to a business process model. Each business process workflow can include a set of interdependent tasks. The workflow server can satisfy received requests by assigning tasks to different service providers that provide software services. Each of the tasks can be assigned to corresponding ones of the software services. For each task, the workflow server can also defines an allocated cost per software service, and a time allocation per software service for completing the corresponding one of the tasks. Different service providers, including those assigned to tasks, can receive information for ones of the tasks not directly assigned to them by the workflow server. The different service providers can then bid on these tasks. Wherein when bids are won, tasks for a business process flow can be reassigned based on winning bids.