Problem Frame Diagram: Simple Behaviour The rectangle with two stripes represents the machine; the plain rectangle represents the problem domain; and the dashed oval represents the requirement. This is an idealised form of a simple control problem. The requirement (Required Behaviour) is to impose a certain behaviour on the problem domain (Controlled Domain). The requirement is expressed in terms of controllable phenomena C3. The interface between the machine (Control Machine) and the controlled
Problem Frame Diagram: Simple Information Answers The arrowhead on the dashed line indicates that the requirement constrains the Responses; the absence of arrowheads on the other dashed lines indicates that does not constrain either the Real World or the Enquirer. The problem is to construct a simple information system (Response Machine) that answers enquiries. Enquiries in the form of an unstructured stream of events E4 come from an autonomous Enquirer; the Enquirer is a biddable domain, as
Problem Frame Diagram: Simple Information Display This is an idealised form of a simple information system (Display Machine) that maintains a continuous display of information (Information Display) about an autonomous causal Real World. The requirement (Display Rules) stipulates the state S4 of the display for each state S2 of the real world. The display is a reactive causal domain, changing its states S4 in response to the machine-controlled phenomena C3. The basic frame concern is the use of t
Problem Frame Diagram: Simple Workpieces This is an idealised form of a problem in which the machine (Tool) acts as a simple tool for the creation and manipulation of text or graphic objects in the Workpieces domain.
Problem Diagram: Package Router Control as a Simple Behaviour Problem The interface between the Router Controller machine and the Router & Packages domain, shown in the left callout, consists of these phenomena: • read: Read events in which the barcode of a package entity is read, and the participating barcoded string is transmitted to the Router Controller. These events are controlled by the Router & Packages domain. • hit: Hit events in which a package hits a sensor. The Router & Packages