P4 – Resource Functions

The P4 Resource Functions View specifies the Resource Functions carried out by all types of Resource (human and non-human), including organisational resources.

Concerns Addressed

  • Capability-Based Acquisition.
  • Business Process Modelling.
  • Workflow Modelling.
  • Human-Machine Interaction Specifications.

Background

The primary purposes of the P4 View are to:

  • Develop a clear description of the necessary data flows that are consumed as inputs or produced as outputs by each resource.
  • Ensure that the functional connectivity is complete (i.e. that a resource’s required inputs are all satisfied).
  • Ensure that the functional decomposition reaches an appropriate level of detail.
  • Provide implementation-specific realisations of the operational activities specified in the L4, Logical Activities View.

The Functionality Description provides detailed information regarding the allocation of functions to resources, and the flow of data between Resource Functions. The P4 View is the Physical Resource counterpart to the L4, Logical Activities View.

Usage

  • Description of task workflow.
  • Identification of functional system requirements.
  • Functional decomposition of systems.
  • Relate human and system functions.

Representation

  • Topological (connected shapes).
  • UML activity diagram.
  • UML activity diagram (with swimlanes to represent resources).
  • Functional Breakdown (decomposition).
  • SysML activity diagram.

Detailed View Description

The P4 View is used to specify the functionality of resources in the architecture. The P4 View is the functional counterpart to the structures specified in the P2, Resource Structure View. The scope of this view may be capability wide, without regard to which resources perform which functions, or it may be resource-specific (usually with the resources depicted as swimlanes). There are two basic ways to depict a P4 view:

  • The functional hierarchy shows a decomposition of Resource Functions depicted in a tree structure and is typically used where tasks are concurrent but dependent, for example, on a production line.

Figure 3-580: Example P4 Hierarchy Schematic

Figure 3-591: Example P4 Hierarchy Schematic with System Context

The functional hierarchy approach may be particularly useful in capability-based acquisition where it is necessary to model the Resource Functions that are associated with particular capability configurations depicted in the P2.

  • The functional flow diagram that shows Resource Functions connected by data and control flow arrows.

Figure 3-602: Example P4 Flow Diagram

Within a physical architecture, P4 flow diagrams document Resource Functions and the flows of data between those functions. Any type of resource may be used in a P4, and it is often used to depict the functional interactions between people and systems.

Figure 3-613: Example P4 Flow Schematic

The Resource Functions may realise L4, Logical Activities, and these activities may optionally be shown in a P4 view, traced to the functions that realise them. The full mapping is documented in the L4-P4, Activity to Function Mapping View.

A P4 functional flow view may be used with ‘swimlanes’ presented either vertically or horizontally. A Resource Function is placed in the swimlane associated with the resource that performs it. This provides a graphical means of presenting the interactions between systems or capability configurations (shown through resource interactions from the P2, Resource Structure View) in functional terms.

Figure 3-624: Example P4 Function Description with Swimlanes

In addition to information flows between functions, a P4 view may show flows of materiel, energy or human resources.

Key Elements and Their Relationships

Meta-Model

The detailed meta-model and element list for P4, Resource Functions, is at paragraph 4.5.4.