SYSML13 — Clarification when Allocated Stereotype is applied

The allocated stereotype is applied to an element at either end of an allocate relationship. This enables the use of the compartment and callout notations to identify what element is on the other end of the allocate relationship. The specification does not explictly state that the allocated stereotype is applied to the elements when the allocate relationship is established. This should be specified as a constraint for the allocated stereotype. This should not imply that the stereotype name must be displayed, but only that the stereotype is applied.

The intent of the derived properties provided by the Allocated stereotype is to enable
the end of the allocation relationship to be identified by the other end, whatever it is.
The approach is similar with derived properties like the “/satisfied” or the “/traceFrom”
from the RequirementRelated stereotype.
The drawback is that requiring these stereotypes to be applied when the
corresponding relation is created implies modifying the elements at one (requirement
related relations) or both (Allocation relation) of its ends. Modification of the elements
involved in the relationship is not possible when one or both of those elements is
read-only and this is likely during the modeling of allocation relationships or of
requirements traceability.
These stereotypes do not actually hold any information by themselves, they only
provide a way to query information owned by directed relationships which may have
been established between the elements they are applied to. The stereotypes
specified that the corresponding derived properties (i.e. the corresponding queries)
shall be available for any model element which is involved in one an allocation or in a
requirement related relationship. The proposed solution consists in adding to the
definition of each relationship the necessary queries in order to provide this facility.
These queries are specified “static” so that they can be used independently of any
relationship instance.
Both the Allocated and RequirementRelated stereotypes can then be suppressed
from the SysML specification. Example of usage with OCL:
Assume “getAllocatedFrom(ref: NamedElement) : Set(NamedElement)” is the static
query defined by the Allocate stereotype to retrieve any named element to which a
given named element has been allocated.
If “X” is a named element “X”, then:
Allocate::getAllocatedFrom(X)
Will give the set of any element to which X is allocated.
Note that the call will not fail even if there is no allocate relationship at all. In this case
or if X is not allocated it will simply return an empty set.