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of the marketing department and so forth. There-
fore, three additional bridge tables are required
for implementing these relations, but for brevity
and comprehensibility considerations these tables
are not presented in Fig. 2.
this term is included in the KW-CM fact table,
making it possible to connect a specific report to
its query, serving also as a report type identifier.
Formalism 1:
Q is the set which represents the
organizational OLAP queries:
kW-cM definitions
Q={y|y is a query processed by the OLAP layer}.
Guideline 1:
In order to build a coherent KW-CM,
the organizational ontology, which holds the report
query terms, should be defined. For instance, in
our example, the Q set includes a query entitled
“UsageOfFeatureX” that aggregates information
from the operational DB and creates a report about
the usage of feature X. This query has a unique
identifier which will be part of the KW fact table.
Definition 2:
A
KW-CM fact
table exhibits the
DW reports that the OLAP layer produced. Each
report is considered a primary event and appears
only once with an identification number, the date
it was issued and its query term, taken from the
organizational ontology.
Formalism 2:
KW-CM includes a RDB that is
defined as
SchKW-CM:={at1=
Ri,
at2=
Qi,
at3=
Date
}
where Ri is the report unique identi-
fier, which is the same identifier in the report
repository, and serves as the RDB primary key;
Qi
Î
Q; and date refers to the day on which the
report was issued. Although the date is part of the
report data, it is inserted in the KW to enable
further KW analysis.
Guideline 2:
The KW-CM fact includes a refer-
ence to a report which exists in one of the orga-
nizational repositories, as well as an ontological
term of its query. The KW-CM fact table is updated
whenever a new report is produced. For example,
the report that was described in guideline 1 above,
will have a correspondence record in the RDB with
an identifier number; Qi=“UsageOfFeatureX”;
and the date it was issued.
Definition 3:
A
KW-CM service
is a linkage to a
service for extracting information from a specific
The conceptual modeling presented here extends
the DW conceptual modeling (Rizzi, 2007)
which addresses the basic concepts of multidi-
mensional DW with additional descriptive and
cross-dimension attributes. A similar method
for expressing the KW-CM definitions is being
used, following formal representation of these
definitions and guidelines for using the definitions
during the modeling process. In what follows, and
due to space limits, only a partial ontology will
be presented and demonstrated. However, these
examples illustrate the basic idea of how to logi-
cally link the various KW components.
In order to formalize the KW-CM, the orga-
nizational ontology terms are presented by sets.
For example, term A is defined as a set: A={x|x
is an item in a set which represents a term in the
ontology} (e.g. queries). Relation “Re” between
terms is represented as a relation: Re(x,y), where
x is the first term and y is the second term (e.g.
query x has “queryRelatesToReport” relation
with report y). A Relational Data Base (RDB)
R is defined as a set of attributes: SchR={ati|ati
is an attribute in a set which represents RDB R}
(e.g. OlapReports).
It should be noted that each organization needs
an ontology that is contextualized to its business
environment. However, future research might fo-
cus on building a general ontology that can serve
as a basic organizational ontology to be refined
according to specific organizational terms.
Definition 1:
A
DW report
is defined according to
its query definitions, assuming that each query type
has a unique term in the organization ontology and
a specific process in the OLAP layer. Therefore,
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