There is a lot to digest here and will have to read the last 3 messages, 2 from Paolo and 1 from Eve, carefully (and possibly more than once).
Let’s start with the following because I think it relates to the question asked by Ian Mitchell
[SNIP]
I agree that down to "BMW X1 with Vin#12345" appear to be specializations. Hence my use in the past of the term specific vs placeholder (rather than specific vs generic, since - to me - generic is not the correct concept to apply)
I agree that "BMW X1 with Vin#12345" appears to be a series of hierarchical specialisations, at least in a UML sense of the term. However, I look at it from a slightly different angle as Paolo, insofar as "BMW X1 with Vin#12345" is a physical car, a car/motor vehicle on the road or inside a showroom or in storage.
This is relevant to Ian Mitchell’s question and to what was the originally discussed in this thread because of the word
"physical", this is the
key word within this thread. The switches previously referred to are
"physical" switches insofar as they have a serial number, the electronic equipment equivalent of a VIN, and most likely an asset identifier.
In contrast "POE Switch" and/or "POE Switch Model" are both classifiers or elements that are/can be specialised or generalised.
This is were ServiceNow comes into the picture. ServiceNow is supposed to give a physical view of the infrastructure and software deployed on it. As a result anything that ServiceNow gives you cannot not be further specialised (but may be generalised/classified, INMHO outside ServiceNow). ServiceNow does not give you a conceptual or logical view of the infrastructure and the Information Systems and Applications deployed and should not be used on its own to produce such views,
although it could be of assistance in producing such viewsAnything physical - i.e.., deployed or to be deployed- can be properly modelled in ArchiMate using
11 Physical Elements, specifically the Equipment element, please see “11.2.1 Equiment”, but
not with any element in the Business, Application and Technology layers. ServiceNow collects physical data and, therefore, the data could be used to construct a physical view. Furthermore, the data could reach enough to partially construct a classification.
Returning to Paolo’s comments regarding specialisation and classification
[SNIP]
In UML, "A classifier is a category of elements that have some common features, such as attributes or methods". Further, "A classifier describes a set of instances that have common behavioural and structural features (operations and attributes, respectively)". And... "A classifier is a type and can own generalizations, thereby making it possible to define generalization relationships to other classifiers." NOTE: How the definitions do NOT say that the Classifier is, itself, an Element. They DO say that it is a categorisation mechanism.
From a UML point of view, assuming we are using a Class element, a couple of questions arise:
1) do we
’classify’ via Class elements and explicit specialisation relationships or via classifiers, which are not elements, in the UML sense of the word?
2) if the former, do we need to add classifiers to the mix and when?
From an ArchiMate point of view, I am assuming that the following elements (from the Business and Application layers) can be generalised/specialised in this way: Business Object, Representation, and Data Object. AFIK ArchiMate does not have the concept of classifier but could be wrong.
By the way "Screw, Whitworth, 3/4 inch" is a model of a screw and not a physical screw to which an serial number could be assigned to. In ArchiMate terms it should not go on under “
11 Physical Elements/11.2.1 Equipment.”
[SNIP]
As an aside, we use the term Classification in the Linnaean sense "Screw, Whitworth, 3/4 inch"
Modern Linnaean classifications use the concept of taxonomic ranks of which there are many types - e.g., Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species. Are these types classifiers or elements? Before answering please consider that taxonomic ranks are organised into a ragged parent/child hierarchy where levels can be skipped.
Please also note that Linnaean classifications stop and species (or sub-species) and do not instantiate each species or sub-species to physical animals, such as my dog or horse.
[SNIP]
ArchiMate uses the words generic and specific for effectively the same concept.
Business actors may be specific individuals or organizations; e.g., “John Smith” or “ABC Corporation”, or they may be generic; e.g., “Customer” or “Supplier”.
The name of a product is usually the name which is used in the communication with customers, or possibly a more generic noun (e.g., “travel insurance”).
From my reading of the spec, if you want to use both and explicitly specify the relationship between specific and generic you would have to use the Specialization relationship. (Well you could use Association. That's the equivalent of Dependency in UML. It can mean anything)
I agree with Eve’s comments and interpretation. Furthermore, if I take Paolo’s example below, I am likely to end up with something like the table after the quote.
[SNIP]
So, let's investigate an ontology with specializations. Vehicle::Motor Vehicle::Motor Car::BMW::BMW X1:BMW X1 with VIN# 12345
In normal usage, we might say that the "BMW X1 with VIN# 12345" specific instance of a BMW X1 (since we can specifically identify the item). We can also say: THE BMW X1 with VIN# 12345 IS a BMW X1 which IS a BMW, which IS a Motor Car which IS a Motor Vehicle which IS a Vehicle. Notice I'm not (directly) saying BMW IS A TYPE OF Motor Vehicle.
| Element name | Relationship (with comments) Comment | Possible UML Type | Possible ArchiMate Element |
| Vehicle | Root (cannot be further generalised) | Class | Business Object, Representation or Data Object |
| Motor Vehicle | An specialisation of Vehicle | Class | Business Object, Representation or Data Object |
| Motor Car | An specialisation of Motor Vehicle | Class | Business Object, Representation or Data Object |
| BMW X1 | A instance of a Motor Car Model | Object (instantiating a Motor Car Model) a missing element in this puzzle | Not sure, possibly an instance of “Motor Car Model” Business Object (or Representation or Data Object) |
| BMW X1 with VIN# 12345 | Not sure because we have transition the physical realm | Possibly a Node or a Device (which is a specialised type of node) | Equipment |
Lastly concerning,
[SNIP]
"Business Process", "Actor" and "Business Role" are the metatypes. Any elements of those types are instances of those types, but from an ArchiMate perspective, they aren't meant to be thought of as instances.
Did you mean that an instance of the metatype Actor is NOT an instance (of Actor)? If so, seems strange!
I don’t think an instance of a Business Process “Assess a Mortgage Application” is a business process. The same way I don’t think an instance of an the actor carrying the process out is an actor. Furthermore, I think it is semantically incorrect to state that the instantiated and the result of the instantiation have the same metatype.
Please think about it, a Class and an instance of it - i.e., an Object - don’t have the same metatype.
What the instantiated Business Process, Actor and Role is, I do not know and I think this were ArchiMate starts creaking.
