Nesting and implicit
When nesting concepts, do the relationships of the nested object also implicitly apply for the 'parent' object?
The concept of ‘nesting’ is not formally defined in the ArchiMate language. In practice however various forms of nesting occurs
1. A visual representation of nesting different concepts
- Figure 5 50: Mix of nested concepts
The advantage of this form is the relatively simple view where relationships are abstracted between different objects towards ‘there is a relationship’. The disadvantage is that in this view it is not known what the exact relationships between the objects are.
2. Hierarchical decomposition
This form of nesting is often used to decompose the same concept into sub concepts. Examples are hierarchical process, function, or organizational structure. The following example shows a process hierarchy.
- Figure 5 51: Nesting through a process hierarchy
Variant 1 indicates the visually nested sub-processes. The relationships between the sub processes and the main process are not visible (but should formally be modeled).
Variant 2 indicates, in this case, the composite relationships between objects. When nesting between the same concepts it is common to use the composition or aggregation relationship.
Both variants model Subprocess-3 with an Access relation towards Object-1. Subprocess-3 is decomposed from Main Process.
According to the rules of derived relations (see good practice 'simplifications and preservation consistency') it holds true that the main process also has the Access relation has with Object-1. Hence with this type of nesting the ‘parent’ object has the same relation as the child object.
Note: Composition or decomposition of a concept is not the same as clustering of similar concepts. For the latter, the concept of 'Grouping' may be used
- Figure 5 52: Clustering using grouping
When ‘visual’ nesting of objects the relationships between these objects must be explicitly described.
Relationships with other good practices
See also good practice: 'Simplification and preserving consistency'