Database Reference
In-Depth Information
Table 7: Determination of conceptual model fi tness (continued)
Entity[notrepl]: Doctor_1
Rel: is
refer-
ence
physi-
cian of
Entity[notrepl]:
Patient_1
p7
X
X
p8
Entity[notrepl]: Doctor_2
Rel:
treats in
emer-
gency
dept.
Entity[notrepl]:
Patient_2
X
X
p9
Entity[notrepl]: Doctor_2
Rel: is
refer-
ence
physi-
cian of
Entity[notrepl]:
Patient_2
X
X
P10
Entity[notrepl]: Patient_2
Rel: is
as-
signed
Entity[notrepl]:
Room
X
X
Entity[notrepl]: Patient_2
Rel:
suffers
Entity[notrepl]:
Complaint
P11
X
X
P12-1
Constraint: no later than
Oper-
and:
P10
P12-2
Constraint: no later than
Oper-
and:
Value: 3 hours
Fitness
.23
.55
.71
.0
.0
.23
Finally, it should be mentioned that it is possible, although not strictly necessary from
the viewpoint of method and technique fi tness calculation, to derive the conceptual models
(such as the class diagram or data fl ow diagram) from the information contained in the GCM.
This derivation is a fully deterministic task, because the RCM has a well-defi ned meaning
in terms of constructors like classes, processes, states, etc., which are the same constructors
as used by the conceptual models.
A derivation procedure based on the use of a set of derivation tables and rules has
been defi ned to get the conceptual models used by the different development methods and
techniques. There are as many tables as there are possible target conceptual models (Dieste,
2003). Each derivation table contains all the possible combinations of Canonical Model ele-
ments that can be expressed in a given conceptual model, along with the expression of this
combination in the particular format used by the conceptual model in question (graphs, text,
tables, etc.). These tables and rules can be used to get fragments of the desired conceptual
model from the propositions it expresses. For example, Table 9 shows a fragment of the
derivation table for the class diagram.
For example, from the proposition Entity[notrepl]: Hospital 123 Rel: admits Entity[repl]:
Patients, we can get the fragment shown in Table 10, as the derivation table contains an
entry Entity[repl] Rel Entity[repl]”.
The different fragments can then be assembled, unambiguously, to get the fi nal version
of the desired conceptual model. The diagram output for the case examined in the example
given in
Table 9 is shown in Figure 6.
The diagram shown in Figure 6 can be later modifi ed to improve or add to diagram
aspects and make the resultant class diagram clearer and simpler.
