Hello everyone.
It occured to me that sometimes, the difference between capability and High-level functions is not clear.
For example, in the IFE example, the Capability ‘Provides Satellite and Internal telephony services’ involve the function ‘Provide Satellite communication means’, which are very close (Even if the IFE system does not detail that part).
More generally, what do you think about systematically creating high level functions with the name of the capabilities ? Is that ‘theoretically’ correct ?
regards,
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Hello,
Personally I don’t consider ‘Provide Satellite communication means’ very close to ‘Provides Satellite and Internal telephony services’. The scope of the latter is wider than the scope of the former.
Generally speaking, Capabilities and Functions are both concepts used to describe behavioral expectations. But the abstraction level of Capabilities is higher than the Function’s. Furthermore, a Function can contribute to several Capabilities.
Systematically creating high-level Functions for Capabilities is redundant and not always useful.
Hope it helps,
Hello,
My understanding is that the notion of capability is equivalent to the notion of use-case: a system usage context further described by a set of interactions between the system of interest and external actors; a collaboration between the system and the actors in order to get a specific outcome.
Regarding the labelling of the capabilities, one question would be to decide on the subject of the action defined by the capability: (1) the system or (2) the actors (implicitly by using the system). Both options seem to be valid and practically in use. The first option might lead to a confusion with a system function. The second option might blur the distinction between operation capabilities and system capabilities. I reckon that some recommendations regarding the phrasing of operational/system capabilities may be useful.
Best regards
Joel
Hello,
When we start a new model, it’s a classic question to ask if this concept is a capability or a system function. In order to answer I ask this question: can I describe this concept by several scenarios or functional chains? Generally it works and sometime I have to go back; but it’s not a big deal, modelling is an iterative process
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For me in SA, Capabilities are always Capabilities of the System; they are necessary to “realize” the missions of the system (the goals of the system.
Hello everyone, thank you for your replies.
they have answered perfectly my question : even if both capabilities and high level functions can be ‘technically’ described by a set of functions ( I oversimplified this for the sake of the clarity ), the first ones are gathered ‘behaviorally’ (like Joel said, it is close to the notion of use-case), whereas the second ones are linked ‘technically’.
best regards,
Julien
Hello all,
I reopen this discussion as I feel that there is not yet, from my point of view, clear distintinctive criteria to clearly distinguish Operational Capabilities and System Functions. I agree on most of what has been said previously. That helps clarifying a bit the difference, but I feel that is not enough.
First, I’d like to share the fact that in my opinion a System Capability and a System Function are basically the same. Anything that is an expection of a behavior that is performed by the System-of-Interest with some performance and under some constraints falls under the definition of a System Function. So I do not see the need of having System Capabilities in the method.
I am interested rather on how to distinguish an Operational Capability from a System Function. The criterion of scope or abstraction level is not sufficient to me to distinguish both. Indeed, a function can very well be used for high level or abstract expression of a need as well as refined and detailed need or solution. That depends on the depth of the system breakdown we are considering.
Both Operational Capability and System Function can be seen as a need expression of an expected behavior whose outcome is required in order to fulfll a Mission, isn’t it ? The only distinctive difference here is the subject realizing it. The Operational Capability is realized collectively by a set of Operational Entities / Actors, whereas the System Function is realized by the SOI. And in some particular cases, the Operational Capability is realized by a single Entity that later can become the SOI.
From this perspective, in my opinion, Capability and Function look like in essence the same concept, but expressed from different points of view (OA, SA).
Another interesting distinctive criteria that I found in the litterature is from definition " Capability is realized through a combination of components that include hard (equipment) and soft (people and processes) systems together with supporting services and infrastructure" (Henshaw and co, Capability Engineering - An Analysis of Perspectives). This definition considers aspects of Capability that go beyond “behavior” (and therefore beyond function) which are for instance less tangible and material such as : processes, knowledge, patents (intellectual property). It considers also infrastructure (a road, a bride, airport infrastructure, etc…) and I think the notion of Service could also be encompassed here. These are in my opinion other potential criteria to better distinguish Operational Capability from System Function.
I’d be happy to have your feedbacks on the subject.
Regards
I think reading the section 4.1 “What is a Capability” from the Arcadia Q&A should give you more thoughts on this.