TRAK Community :: Wiki :: NAF:NSV-1 System Interface Description Subview

Overview

The NSV-1 System Interface Description subview is part of the NATO System View and one of the 49 NATO Architecture Framework subviews.

Version & Date

Version 3.1

* = changed at 3.1

+ = new at 3.1

The change history is derived from the definition of each NATO Architecture view within section 5.2.6 NATO System View (NSV) in AC/322(SC/1-WG/1)N(2009)0005-ADD2. NATO Architecture Framework Version 3.1 document from https://www.nhqc3s.nato.int/Browser.asp?Target=_docs/NAF_v3_1 .

See NAF Release History.

Purpose

From the NATO Architecture Framework v3, CHAPTER 4, Section 4.7.1

The purpose of the System Interface Description is to illustrate which systems collaborate in which way to support the operational domain’s information and information exchange needs as defined in the Operational View; most notably in NOV-2 and NOV-3.

Covered by NATO release conditions.

Description

From the NATO Architecture Framework v3, CHAPTER 4, Section 4.7.1

NSV-1 links together the NATO Operational View and the NATO System View by depicting which systems and system connections realize which information exchanges.

A system is defined as any organised assembly of resources and procedures united and regulated by interaction or interdependence to accomplish a set of specific functions. The term system in the NATO System View is used to denote software intensive systems, which may be classified as Federation of Systems (FoS), System of Systems (SoS), subsystems, or system components. Furthermore, the term may denote logical systems as well as physical products, current systems as well as future systems.

The term ‘system’ is used to denote a web service (or a composite web service, or a set of interacting and orchestrated web services, etcetera). Network components and other hardware components, such as routers, satellites and network segments are also seen as systems or elements of systems, and as such can be included in NSV-1 diagrams, especially if these diagrams are used to model distribution aspects.

A system’s services are accessed through the system’s interfaces. In general, an interface is a contract between providers and consumers of (system) services. With regard to software intensive systems, the contract is a declaration of a coherent set of public system functionality. The system’s interfaces, in effect, specify the behaviour without specifying implementation specifics.

An NSV-1 connection between system interfaces is the systems representation of an NOV-2 needline or NOV-3 information exchange. A single needline or information exchange may translate into multiple connections between system interfaces.

The following are documented in an NSV-1:

systems and their interfaces

system use dependencies between interfaces

Data Objects

From the NATO Architecture Framework v3.1, CHAPTER 5, Section 5.2.6.1

The data in an NSV-1 can include:
Artefact

Organisation Type

Post Type

Role Type

Software

Capability Configuration

Resource Interaction

These functions can optionally be overlaid on an NSV-1.

This suggests that Function should be in the data objects list.

Covered by NATO release conditions.

Presentation

Configuration History*

3.1 adds Artefact (removing System, Physical Asset) removes Resource Composition, adds Software and changes Role to Role Type in data objects. All resources can have a Resource Interaction.
3.0 Resource Interaction restricted to NAF::Functional Resource - Role, NAF::System, Capability Configuration

Comments

Unlike the MODAF::SV-1 the purpose of the subview is clearly stated as interface identification. The interfaces identified here are then characterised in the NAF:NSV-2. MODAF claims that the MODAF:SV-1 has a structural focus but the name of the view and definition of the view content doesn’t support this claim. It will be interesting to see what the words in Chapter 4 of NAF 3.1 say when they’re released.

There is a large amount of overlap between the NSV-1 and NSV-2 which doesn’t help - see ‘Keep Clear Separation Between the Concerns that Each Architecture View Addresses’.

The definition of system in this view description is inconsistent with the definition of the ‘system’ stereotype in the NATO Architecture Framework Metamodel. The latter, which is the basis for NATO System Views, is only ever a physical artefact and cannot be software or anything else. NAF:System cannot have anything configured and is defined as not being able to have capability so the suspicion is that Capability Configuration is being used to represent a system. If system is defined in the metamodel why not use that?

What is a ‘logical system’? This is easily confused with Node which can be regarded as a logical definition as it never includes any notion of how it is implemented.

It also looks from this definition as if Post / Post Type, Organisation is not a Functional Resource and cannot therefore have interactions with anything else.

There is a lot of narrative about usage of… some NAF stereotype which confuses types with arrangement or configuration. Something is a type because it meets the tests in terms of the type defining behaviours/attributes not because of usage i.e. usage doesn’t transform something from one type to another:

Physical Asset – an artefact may be used as a platform or a system

The problem is caused by platform and system concepts overlapping i.e. something may be both a platform and a system. In forcing a subjective choice NAF (and similarly MODAF) resulted in inconsistent representation.

References

Section 4.7.1 (page 234 of pdf) of APPENDIX 1 TO ANNEX 1 TO AC/322-D(2007)0048. NATO Architecture Framework Version 3.
Section 5.2.6.1 (page 409 of pdf) of APPENDIX 5 TO ANNEX 1 TO AC/322-D(2007)0048. NATO Architecture Framework Version 3.
Section 5.2.6.1 of Chapter 5 AC/322(SC/1-WG/1)N(2009)0005-ADD2 NATO Architecture Framework Version 3.1
The Residual World. Keep Clear Separation Between the Concerns that Each Architecture View Addresses. https://trak-community.org/index.php/residualWorld/comments/keep_clear_separation_between_the_concerns_that_each_architecture_view_addr

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