View MODAF:OV-2 Operational Node Relationship Description View



The OV-2 Operational Node Relationship View is part of the MODAF Operational Viewpoint and one of the 47 MODAF views*.

Version & Date

Version 1.2.004.

* =  changed at 1.2.004

+ =  new at 1.2.004

The change history is derived from the definition of each MODAF view within the The MODAF Operational Viewpoint viewpoint defining document from

See MODAF Release History.


From The MODAF Operational Viewpoint p10:

The OV-2 shows, at a high level, the interactions between logical nodes and depicts the capabilities that those nodes bring to the architecture.

Subject to Crown Copyright


From The MODAF Operational Viewpoint p10:

The primary purpose of the OV-2 is to specify nodes (elements of capability) in context with each other. The context is usually expressed in terms of the information that flows between the nodes (e.g. the information flow requirements between capabilities in a given scenario). However, the context may also be flows of materiel, human resource or energy.

With MODAF V1.2, the OV-2 has been developed to:

  • Adopt a more formal definition of logical flows to represent node connections.
  • Support the introduction of Service Oriented Architecture (SOA).
  • Accommodate the use of known resources (as defined in SV-1).

Subject to Crown Copyright


From The MODAF Operational Viewpoint p12:

The OV-2 depicts nodes and the needlines between them, primarily to indicate a need to exchange or share information. The OV-2 may, however, also show the location (or type of location or environment) of nodes, and may optionally be annotated to show flows of people, materiel or energy between nodes.

The primary purpose of an OV-2 is to define the logical structure of architecture. Building on the strategic intent identified in StV-1, Enterprise Vision, OV-2 takes the required capabilities and expresses them as nodes which interact by exchanging information or producing / consuming services.

The nodes in the logical architecture do not represent specific organisations, systems or locations. This enables Information Exchange Requirements (IERs) to be established without prescribing the way that the information exchange is handled. OV-2 does not, therefore, depict the physical connectivity between the nodes. An OV-2 can be a powerful way of expressing the differences between an as-is architecture and a proposed architecture to non-technical stakeholders, as it can be used to emphasise how information flows (or does not flow) without becoming over-complex. OV-2 indicates the key players and the interactions necessary to conduct the corresponding operational activities of an OV-5, Operational Activity Model ...

From The MODAF Operational Viewpoint p13:

The diagram may include the needline identifiers as numerical labels .... Alternatively short phrases may be used.

Because needline identifiers are often needed to provide a trace reference for information exchange requirements (see OV-3), a combined approach with numerical and text labels can be used. In most cases there will be only one [MODAF:Needline|needline]] between any two nodes (which may carry multiple information exchanges). This is not mandatory, however, and the architect may choose to group the exchanges into more than one needline.

There is a one-to-many relationship from needlines to information exchanges (e.g. a single needline in OV-2 represents multiple individual information exchanges). The mapping of the exchanges to the needlines of OV-2 occurs in the OV-3, Operational Information Exchange Matrix. For example, an OV-2 may have a needline labelled “Situation Report” which represents a number of information exchanges, consisting of various types of reports (information elements), and their attributes (such as periodicity and timeliness). The identity of the individual elements and their attributes are documented in OV-3, along with the producing and consuming activities from OV-5, Operational Activity Model.

Subject to Crown Copyright

Data Objects*

From The MODAF Operational Viewpoint p8:

The data in an OV-2 can include:

Subject to Crown Copyright


From The MODAF Operational Viewpoint p11:

  • Topological (connected shapes).
  • UML composite structure diagram

Subject to Crown Copyright

Configuration History

1.2.004 adds Security Domains, Trust Lines, Services


The data objects section isn’t consistent with the text in the viewpoint document since the OV-2 can also include Known Resources.

A Known Resource is a Resource (Type) that is defined as always being part of the solution. It is a constraint on the (possible) solution.

Node is described as an element of capability whereas the official definition in the M3 is much less useful (The usage of a NodeType in another NodeType or LogicalArchitecture.).

The official change log, Change Proposal K, adds Security Policy which doesn’t appear in the text or data objects.

The ability to describe exchanges of energy, materiel and people flows to the existing information exchange is welcome. The way in which it is achieved is inconsistent, however - why should they be represented differently from information exchange? Why is a needline only related to an exchange of information and not any other type of exchange? The most likely explanation is the way in which the definition of MODAF::Needline at 1.2.003 - a need to exchange information between nodes got changed to A relationship between Nodes representing a bundle of InformationExchanges and in doing so lost the definition of the thing in the real world being represented (a need for something) in favour of a description of the M3 itself - not much help. Having lost the sense of describing a need it was probably a small step then to break out the new parts of the M3 and not include them as needs for these new types of exchange.

Other Frameworks

See also:


Category:Framework -> View
Category:MODAF -> View



© 2010 Eclectica Systems Ltd.