Friday, March 28, 2008
Modelling processes to scale
Tasks in process models come in varying sizes. There is a key distinction that divides tasks in process models into two classes: is this task at the "plannable" or "sub-plannable" level. Plannable tasks appear on plans, Gantt charts, burndowns and crucially time-sheets. They are the kind of tasks that take from several hours to days or even weeks. Plannable tasks are the trackable planned, estimated and costed elements in xProcess. However in some processes we wish to define (and monitor) tasks at the sub-plannable level. For example if my tasks is to distil a certain compound from ingredients (in a chemical process), the steps in the process may need to separately defined and tracked to ensure quality compliance. xProcess provides a mechanism to support this in the "Gateway Type". While these steps form only a simple sequence in v2, we've recently been experimenting with a richer model for gateways that will allow the same kind of forms - selections, collections, iterations and sequences - that are supported in plannable tasks through the composite structures. Together these facilities make a continuum of process modelling from from large to small scale.