1. A method comprising: specifying a task set including workflow tasks; specifying a constraint set including constraints that specify how the tasks within the task set may be implemented with respect to one another, to thereby define valid subsets of the task set, wherein the constraint set ensures that each task may be implemented in at least one valid subset; initiating a workflow that requires at least one of the tasks; assembling a subset of the tasks, the subset matching one of the valid subsets; and implementing the subset within the workflow.