P8 – Resource Constraints

The P8 Resource Constraints View specifies functional and non-functional constraints on the implementation aspects of the architecture (i.e. the structural and behavioural elements of the Resource layer).

Concerns Addressed

  • Non-Functional Requirements.
  • Safety Cases.

Background

The P8 View describes constraints on the Resource Types, Resource Functions, data and Ports that make up a Physical Architecture.

The P8 View describes the rules that control, constrain or otherwise guide the implementation aspects of the architecture. Resource constraints are statements that define or constrain some aspect of the technology or business, and may be applied to resources, functions, system ports or data elements. Resource constraints are categorises as follows:

  • Structural assertions – non-functional constraints governing some physical aspect of the architecture.
  • Action assertions – functional constraints governing the behaviour of resources (constraints on functions).
  • Derivations – these involve algorithms used to compute facts.

Where a resource constraint is based on some standard, then that standard should be listed in the A8,Standards Profile.

Usage

  • Definition of implementation logic.
  • Identification of resource constraints.

Representation

  • Text (preferably specified in a computer-interpretable constraint language such as OCL). • Tabular.

Detailed View Description

The P8 constraints are specified in text and may be functional or structural (i.e. non- functional). Some resource constraints can be added as annotations to other views, in which case the P8 should provide a listing of the complete set of those rules and any others that are not shown in other views.

With potentially complex resource constraints it may be more useful to express these rules in OCL, as shown in Figure 3-71:

Figure 3-71: Example P4 View with P8 OCL Constraints Embedded in Functions

Key Elements and Their Relationships

Meta-Model

The detailed meta-model and element list for P8, Resource Constraints, is at paragraph 4.5.10.