Legal information

Copyright DB Netz AG, licensed under CC-BY SA 3.0 DE (see full text in CC-BY-SA-3.0-DE)

ARCH.058 Define measures of performance

GoalGain understanding of the system characteristics that are considered necessary to achieve the measures of effectiveness
Requirements met by this process stepISO 15288 6.4.3.2 c) / 6.4.3.3 c) 2)
Inputs

AMOD-106 Enterprise goals (modified after ARCH.009 Define measures of effectiveness)

Any existing version of AMOD-057 Measures of performance

OutputsAMOD-057 Measures of performance (updated, if it already existed)
Methodology

For the capability of interest:

Consider the context of the system capability and what operational capabilities are supported by it;

Given the system functionality, data and statefulness being modelled in parallel, identify what should be measured in order to support a claim that the measures of effectiveness have been achieved;

Re-use existing measures of performance where appropriate, rather than creating new ones; target values can be made more stringent if necessary;

If existing measures of performance are suitable, but their target values are more stringent than is needed for the capability of interest

Leave the target value as it stands (since, if reached, the needs of the capability of interest are met)

Note that this measure of performance is also needed for the capability of interest (ensuring that it will not be removed later or reduced in stringency without examining its impact on the capability of interest)


Measures of performance are distinct from the measures of effectiveness already created, because they are focused on the system and not on the wider stakeholder environment. In other words, they are formulated from different viewpoints: MoEs from the stakeholders' viewpoint, MoPs from the viewpoint of the "supplier" of the system of interest.

The intent of defining MoPs is to answer the question "how well must the system perform in order that the system's stakeholders can achieve their mission?".

Each MoP contributes to the evaluation of one or more MoEs.

Measures of performance should be stated in technical, measurable terms but they are distinct from non-functional parameters in that they do not necessarily need to be specified directly on the outputs of functions or the quality of individual types of data; they should be a little higher-level. The individual non-functional parameters will be defined in the risk assessment stage ARCH.915 Assess & mitigate the risks of system failure and will, in turn, contribute to the achievement of the MoPs.

They can be used as a basis for verification criteria.

MoPs may emerge whenever a new capability is assessed, but the set of MoPs should be engineered alongside the set of capabilities, with strong consultation with other system architects and the lead system architect so that a coherent approach is taken.

Example

Measure of effectiveness: the capacity of the network is x trains per hour in each direction.

Possible measures of system performance:

  • the number of trains that the system can support simultaneously is greater than or equal to y
  • the processing time for the system to provide a safe authority for a train unit to follow a preceding train unit is no greater than z


Tools and non-human resourcesTeam for Capella
CardinalityOnce per system capability
Completion criteriaSufficient MoPs have been defined for the capability of interest.
Design reviewARCH.R.3 System capability review
Step done by (Responsible)Lead system architect
Provides input to/assists (Contributes)
  • System architect
  • Operational concept architect
Uses outputs (Informed)Not defined