Information Technology Reference
In-Depth Information
4 Operations of EA Models
We identify six operations on EA models: Projection, Instantiation, Specialization,
Refinement, Derivation, and Linking. Table 3 summarizes the operations.
Table 3.
Operations on EA Models
*
Operation Description
Projection Transforming a (set of)
objects
by selecting a subset of
attributes
Instantiation Creating a (set of)
objects
/
events
based on a construct in the meta-model
Refinement Elaboration of a (set of)
conceptual objects
/
events
by addition of
invented
attributes
; Decomposition of a (set of)
conceptual objects
/
events
by
identifying
component objects
Specialization Adding variations to a (set of)
objects
by adding
invented attributes
Derivation Manipulation of
attributes
of a (set of)
objects
to derive values for related
objects;
Transformation of
objects
into other
objects
Linking Establishing a connection between a (set of)
objects
/
events
* Note: The description uses constructs from the ontology (see Table 2), shown in
italics
.
4.1 Projection
Projection (P) refers to the transforming of an object into a form that consists only
of those properties that a stakeholder requires. It is analogous to the existential quanti-
fication operation in predicate logic. The essential characteristic of Projection is
discarding some information as a surjective and unary operation while preserving
'type'. Consider, for example, a shipping container manufacturer who uses a corrugat-
ing machine to produce a range of cardboard stock that must be cut, printed, folded,
and glued on many machines to meet particular customer specifications. A Projection
may involve extracting information related to machine capacities to structure a con-
veyance system that accumulates and forwards the stock to the appropriate printer and
box machines.
4.2 Instantiation
Instantiation (I) is a constructive step. It adds the detail necessary for constructing a
reification of a concept. For concrete entities, this can lead to tangible things in the
world. For conceptual entities, instantiation can require assigning values to invented
attributes. During the EA cycle, instantiation may
first
occur for the purpose of
constructing an EA model from the framework or standard. A
second
level of instan-
tiation may occur during the mapping and use of the EA model against specific
instances of an Activity or Node. Instantiation of the first kind takes place during the
design phase, whereas the second kind takes place during use of the EA models.
4.3 Refinement
Refinement (R) is an information adding operation. The essential characteristic of
Refinement is the preservation of boundary. During an EA life cycle, Refinement is
critical because it allows addition of information beyond the original creation of an
