The Structure of the NATO Architecture Framework

The Framework will ensure that architectures developed according to this framework can be understood, compared¹ , justified and related across many organisations, including NATO and other National Defence initiatives.

The traditional approach to development has often resulted in a collection of disparate systems procured and provided by the Nations that perhaps could be interconnected but were never interoperable such that the combination was aligned with an organisation’s goal.

As a result of this situation systems failed to bring the expected benefits like interoperability, speed of operation, cost reduction and flexibility to change.

The solution to this is to think strategically and understand an organisation’s overall objectives. From these objectives the actual content and the structure of the systems can be derived. The rules, constraints and guidelines on how to develop capabilities and systems including information systems to support the business, is a central element for architects.

Architectures have to transform strategy into the content of manageable and executable change.

The NAF complements the ISO/IEC 42010 conceptual model to include enterprises and phases of an enterprise. In this way Architectures can be used to show how they develop and undergo change over time through a process of transformation.

NAF v4 introduces the concepts of Logical and Physical viewpoints or perspectives on an architecture.

The NAF Viewpoints retain equivalence with the NAF v3 Views² , albeit with names that better describe their purpose, as indicated in Table 1-1: Mapping of NAF v3 Views to NAF v4 Viewpoints:

Table : Mapping of NAF v3 Views to NAF v4 Viewpoints

Note: This table must not be read as a strict mapping between NAF v3 views and NAF v4 viewpoints.

• A Logical viewpoint the logical components of the architecture without specifying their physical type – that is it leaves the implementation options open, even to the level of allowing human or machine solutions to a particular problem. It may also be used to present a view of an existing system to allow stakeholders to understand the structure and behaviours free of the physical complexity.

• Physical viewpoints are used to describe patterns or provide a detailed view of a system.

It is worth noting that the terms Logical and Physical have different meanings in other engineering domains.

In NAF v4 the term Logical is used to denote the realisation of capabilities (defined in the Concepts viewpoint) that is still independent of a solution. The Logical viewpoint (still and partly) describes the problem space.

The term Physical is used to denote the realisation of logical entities (defined in the Logical viewpoint) by a solution. Thus, the Physical viewpoint describes the solution space.

In some engineering domains, the solution space is defined by two levels:

• a Logical level defining the principle of the solution

• a Physical level defining the concrete / detailed solution

Definition of Viewpoint

ISO42010 defines an Architecture Viewpoint as “An architecture view expresses the architecture of the system-of-interest in accordance with an architecture viewpoint (or simply, viewpoint). There are two aspects to a viewpoint: the concerns it frames for stakeholders and the conventions it establishes on views”. The NAF represents a number of views according to the following viewpoints:

• Concepts viewpoint – enterprises and their capabilities.

• Logical viewpoint – solution-independent specifications of how capabilities and services are orchestrated for particular scenarios.

• Service viewpoint – how capabilities are packaged for re-use across the enterprise.

• Physical Resource viewpoint – high-level design, specifying the required structure and interactions between systems, people and organisations.

• Architecture Management viewpoint – who produced the architecture, when and for whom? Also specifies how the Viewpoints fit together and what concerns they address.

These are described in Chapter 3 along with the Ontology and View Taxonomy.

The viewpoints describe the problem and/or a solution with regards to several concerns or perspectives:

1. The Concepts and Service viewpoints are used to describe capabilities and services that are then re-used throughout the architecture.

2. The Logical viewpoint specifies how capabilities and services are needed to meet a given requirement or scenario.

3. The Physical viewpoint describes how those capabilities and services are implemented and how they interact.

4. The Architecture Management viewpoint specifies how the other viewpoints fit together and what concerns they address.