Information Technology Reference
In-Depth Information
EconomicResource
<<EconomicResource>>
Fish
<<stock-flow>>
<<EconomicResource>>
Cash
stock-flow
<<stock-flow>>
+initiating
+initiating
+terminating
<<EconomicEvent>>
Payment
<<EconomicEvent>>
FishSale
EconomicEvent
<<duality>>
<<
duality
>>
+terminating
receive
<<
outside
>>
provide
<<
outside
>>
provide
<<
inside
>>
receive
<<
inside
>>
outside
inside
<<EconomicAgent>>
Salesperson
<<EconomicAgent>>
Customer
<<EconomicAgent>>
Cashier
EconomicAgent
(a) REA Meta Model
(b) REA Object Constellation
Fig. 1.
Basic REA Ontology
types are distinguished:
give
and
take
(transfer events),
use
,
consume
,and
pro-
duce
(transformation events). Participation relationships describe the involve-
ment of an agent in an economic event. As such, the basic REA ontology not
only conceptualizes economic exchanges but also relates to business process con-
cepts. It captures
Who
is involved in an exchange (
economic agents
),
What
is
being exchanged (
economic resources
),
When
(and under what conditions) do
the components of an exchange occur (
economic events
),
Why
are the partici-
pants engaged in an exchange (
duality relationships
,
stock-flows
), and
How
do
the exchanges materialize as economic activities or business processes (series of
small events that move business process through to completion) (cf. [12]).
The basic REA ontology with its economic primitives is illustrated in Figure
1(a) by means of a UML class diagram. Figure 1(b) shows an instantiation of
the REA ontology, a so called object constellation. Furthermore, the ontology
defines three axioms that restrict the use of the concepts and primitives for
conceptualizing economic exchanges (cf. [11]):
- Axiom 1:
At least one take event and one give event exist for each eco-
nomic resource (guarantees modeling of economic activities as a sequence of
exchanges).
- Axiom 2:
All events effecting a resource decrement must be eventually
paired in duality relationships with events effecting an increment and vice
versa (ensures correct enumerations of exchanges).
- Axiom 3:
Each exchange needs an instance of both the ”inside” and the
”outside” agents(ensures presence of exchanges between parties with com-
peting economic interests).
Axioms one to three apply for transfer events. Axiom two also holds for trans-
formation events.
Since its proposal in 1982, some extensions to the basic REA ontology have
been proposed (e.g. [5]). The extended REA ontology envisions a vertical and
horizontal layering of economic exchanges. With regard to the vertical layering, a
hierarchy consisting of three levels is proposed: (1) the
value chain
specification
level, (2) the
duality
specification level, and (3) the
task or workflow
level ([5]).
In this paper we focus on the upper two specification layers: the value chain and
the duality . Thereby, we base our work on the diagram style used by Geerts
and McCarty in [13], which has never been formalized.
