NAF v3: NSV-2/6 MODAF: SV-2/6
Physical Data Model
The P3 Systems Connectivity view describes communications networks and pathways that link communications systems, and provides details regarding their configuration.
The networks and pathways documented through these views represent the physical implementation of the information needlines identified in an L2 – Logical Scenario or L3 – Node Interactions view.
The P3 focuses on the physical characteristics of each link by specifying attributes. An example of this might be the geographic location and layout of network components such as routers, switches, amplifiers and repeaters. Attributes such as capacities (eg bandwidth, throughput), frequencies used, security encryption methods used and other descriptive information is usually presented in a corresponding SV-6 product (though most architecture tools would prompt the architect to enter such data as the P3 products are being developed). The P3 covers the SV/NSV-2a,b,c views from previous versions of MODAF/NAF, which define the communications links between systems:
- SV-2a System Port Specification – defines the ports on each system, and the protocol / hardware stack that is specified or implemented for each of those ports.
- SV-2b System to System Port Connectivity – defines the connections between individual ports and shows the protocols and hardware spec used for each connection.
- SV-2c System Connectivity Clusters – defines the bundles of system to system connections that go to make up a connection between the Artefacts that host the connected systems (see SV-1).
The purpose of P3 is to provide a comprehensive specification of how systems are connected, what interfaces each system exposes (ports), the hardware interface used and the protocols transmitted across the interface. Key elements are repeated from view to view and are also common to the P2 – Resource Connectivity view. These key elements are:
- Artefacts (represented as Systems and Platforms).
- System Port connections.
The elements are shown in different perspectives in the different views. In an P2 the resources (including systems) are logically grouped by the artefact to which they belong (which could mean located with). The P2 view also shows how human operators (‘roles’) interact with systems. In the P3 views, more information is added; in particular, information about the ports on each system and the protocols which each port supports. In addition, the P3 views describe which protocols are supported for specific system-to-system connections. In a P3, the focus is on systems and the capability configurations they are part of.
It is important to understand the differences between P2 and P3 to ensure that the correct detail is captured in each view. In essence, the P3 series expands on the P2 by providing more detail of the physical characteristics of those interactions specified in the SV-1 that are between systems. For example, the P2 interaction perspective shows a single-line representation of interfaces between nodes, whereas the P3 would show a more detailed representation of the communications infrastructure that provides the connections.
The P3 view uses the common term ‘protocol’ as a specialisation of the NAF term ‘standard’ to describe the standards specifically used in interface and communication specifications.
Detailed View Description
Key Elements and Their Relationships
The detailed meta-model for P3 can be viewed here