L4-P4 – Activity to Function Mapping

The L4-P4 Activity to Function Mapping View provides two alternate views:

• It addresses the linkage between functions described in P4, Resource Functions, and operational activities specified in L4, Logical Activities.
• It addresses the Resource Functions from the P4 View and the Service Functions from the S4 View.

Concerns Addressed

• Requirements Definition.
• Process Mapping.

Background

The L4-P4 View depicts the mapping of Resource Functions (and optionally, the resources that provide them) to operational activities or service functions. For operational activities it thus identifies the transformation of an operational need into a purposeful action performed by a system or solution. For service functions it provides the link between the services used at the operational level and the specific Resource Functions provided by the resources supporting the services.

Note that the NAF uses the term ‘Operational Activity’ in the Logical Specifications layer and the term ‘Resource Function’ in the Physical Specifications layer to refer to essentially the same kind of thing, that is, both activities and functions are tasks that are performed, accept inputs, and develop outputs. The distinction between an Operational Activity and a Resource Function is a question of “what” and “how”. An Operational Activity is a specification of what is to be done, regardless of the mechanism used whereas a Resource Function specifies how a resource carries it out. For this reason, the L4-P4 is a significant View as it ties together the L4, Logical Activities, with the P4, Resource Functions. This logic can also be applied to Services where the S4, Service Functions, is a specification of what functionality is to be delivered, specified independently of implementation.

The relationship between Resource Functions and Operational Activities may be many-to-many (i.e. one activity / service function may be supported by multiple Resource Functions and one Resource Function may support multiple activities / service functions).

Usage

• Tracing functional system requirements to user requirements.
• Tracing solution options to requirements.
• Identification of overlaps.

Representation

• Tabulation.

Detailed View Description

A L4-P4 view is normally a matrix showing the relationship between Resource Functions, and operational activities / service functions.

Figure 3-635: Example P4-L4 View

A L4-P4 view may be further augmented with the Resource Types (e.g. artefacts, roles, capability configurations etc.) that conduct the Resource Functions. The architect may also wish to hide the Resource Functions in a L4-P4 view so that the table simply shows the mapping from Resource Types to operational activities / service Functions.

Figure 3-646: Example Variant P4-L4 View (Systems Mapped to Operational Activities)

During requirements definition, a L4-P4 view plays a particularly important role in tracing the architectural elements associated with system requirements to those associated with user requirements.

Key Elements and Their Relationships

Meta-Model

The detailed meta-model and element list for L4-P4, Activity to Function Mapping, is at paragraph 4.5.5.