Figure 11 The standard pattern of a transaction.
The initial C-act is drawn with a bold line, as is every terminal C-fact. The gray colored frames
denoted by "initiator" and "executor" represent the responsibilities of the two partaking actor roles. The
steps in the transaction process are ideal candidates for the functions (use cases) of the AIS. These are the
atomic components of business processes, there is nothing more to support. Using ORM, one (only) has to
decide which actions will be supported and how, and which will not.
As a third contribution to ORM, DEMO distinguishes between the dynamics of the BS and AIS. Every
C-fact may serve as an agendum (singular of agenda) to be dealt with by an actor. Typically, an actor
disposes of a set of agendums, or agenda. In dealing with an agendum, one or more new agendums may be
generated. This constitutes the dynamics of a BS. The dynamics of the AIS is basically asynchronous with
respect to the dynamics of the BS. They coincide only when products of the AIS are declared to count as
acts in the BS (like we have seen for an automated stock control system). In all other cases, the C-acts must
be made known to the AIS.
Consider for example the borrowing of a library book. This transaction of type T04 starts with a
member request. The resulting C-fact "requested" is entered in the AIS. At the same time, a new instance of
Loan is created by the AIS, including the facts that existentially depend on it ("the membership of L is M"
and "the book copy of L is C"). Ideally, the recorded time stamp of the C-fact is the real time (valid time) at
which it was created in the BS. It is however common practice to take the time of entering into the AIS
(transaction time) as the time stamp. This usually causes no problems since the order in which the steps of
Figure 11 are entered in the AIS is easily controlled by the AIS. For example, a promise fact is rejected by
the AIS if there is no corresponding request fact. If the transaction succeeds, the terminal state is the C-fact
"ac" (accepted). At the time of establishing this fact, the production fact becomes existent. From that time
on, the loan really exists in the BS. This definition is easily implemented in the AIS: as soon as the
accepted fact is entered, the loan exists (there is only the unavoidable time delay with the BS)