Rights and Intentions in Value Modeling - Intentional Perspectives on Information Systems Engineering - page 193

as a reaction to traditional business accounting where the needs are to manage busi-
nesses through a technique called double-entry bookkeeping. This technique records
every business transaction as a double entry (a credit and a debit) in a balanced
ledger.
The core concepts in the REA ontology are resources, events, and actors. The
intuition behind the ontology is that every business transaction can be described
as events where two actors exchange resources. To get a resource an agent has
to give up some other resource. For example, in a purchase a buying agent has
to give up money to receive some goods. The amount of money available to
the agent is decreased, while the amount of goods is increased. There are two
events taking place here: one where the amount of money is decreased and another
where the amount of goods is increased. This correspondence of events is called
a duality. A corresponding change of availability of resources takes place at the
seller's side. Here the amount of money is increased while the amount of goods is
decreased.
2.2 The e3value Ontology
The e3value ontology [6, 7] aims at describing exchanges of value objects between
business actors. It also supports profitability analysis of the business model created.
The basic concepts in e3value are actors, value objects, value ports, value interfaces,
value activities and value exchanges, see Fig. 1. An actor is an economically inde-
pendent entity. An actor is often, but not necessarily, a legal entity, e.g., enterprises
and end-consumers. A value object is something that is of economic value for at
least one actor, for example a car, Internet access, or a stream of music. (We will
sometimes use “resource” as a synonym for “value object”.) A value port is used by
an actor to provide or receive value objects to or from other actors. A value port has
a direction, in (e.g., receive goods) or out (e.g., make a payment) indicating whether
a value object flows into or out of the actor. A value interface consists of in and out
ports that belong to the same actor. Value interfaces are used to model economic
reciprocity. A value exchange is a pair of value ports of opposite directions belong-
ing to different actors. It represents one or more potential trades of value objects
between these value ports. A value activity is an operation that could be carried out
in an economically profitable way for at least one actor.
Fig. 1 Basic e3value concepts