used by current IS developers because UML has
been approved by the Object Management
Organization (OMG) as a standard since 1997. On
the contrary, for both OC and norms, it is their
obvious drawbacks that they are used at present only
by a small group of people and no commercial effort
has been made to popularize them yet. Moreover, at
the semantics level, as an important and
indispensable relationship, OD are modelled directly
and clearly in OC but not defined in UML UCD and
CD (Xie, Liu and Emmitt, 2003), (Bonacin,
Baranauskas and Liu, 2004) and (Ades, Poernomo
and Tsaramirsis, 2007). At the pragmatics level,
three deontic operators are specified in norms but not
defined in UML AD, which make the presentations
of communications and the analysis of purposes in
communications more precise. On the other side,
UML AD can model communications directly and
obviously but norms cannot, which make the
analysis of purposes in communications much easier.
At last, it is their common drawbacks that purposes
in communications cannot be modelled formally and
obviously in both of them. At the social world level,
similarly, three deontic operators are specified in
norms. However, in UML AD, business rules rather
than norms are specified indirectly. As stated in (Liu
and Ong, 1999): “with the help of the deontic
operators, norms can handle both business rules and
exceptions, which are situations difficult to
anticipate and specify in advance and are situations,
where decisions occur on an ad hoc basis and are
made solely on human judgment”.
4 THE METHOD TO EXTEND
UML AD
As Kecheng Liu stated that “A sound modelling
method must cover the issues in semantic, pragmatic
and social aspects. Issues at the three semiotic levels
are closely related. The focus must be first on
semantic issues. A model containing a clear
description about the organization, which may be in
terms of general patterns of actions, states, etc., is
the first bases for further analysis. The model of this
kind can be taken as a foundation on which the
intentions of actions can be discussed. Furthermore,
the rationales, limits and consequences of the actions
at the social level can be addressed” (Liu, 2000).
As pointed out previously, UML AD can model
communications directly and obviously but norms
cannot, which make the analysis of purposes in
communications much easier. In addition, UML AD
are widely used by current IS developers as an OMG
standard. Furthermore, although no deontic operators
are defined in UML AD, it is not hard to extend
them with “permitted”, “prohibited” and “obliged”
to handle exceptions as norms. In conclusion, it is
more reasonable to choose UML AD rather than
norms as the formal results to model business both at
the pragmatics and the social world level in the
combined BMM envisaged, which is supposed to
keep the merits and avoid the drawbacks each of the
BMMs has.
To extend UML AD with “permitted”,
“prohibited” and “obliged”, only three simple rules
below have to be followed:
Each transition pointing to an activity state
should be extended with one of the three
deontic operators;
When the “permitted” or the “prohibited” is
used, the text “permitted” or the text
“prohibited” must appear at the end of the
guard condition and separated with the guard
condition by “/”;
When the “obliged” is used, the text “obliged”
can be omitted. Otherwise, it should appear at
the same place as the other two.
For example, figure 6 shows the UML activity
diagram derived from a slight modification of a
Workflow Activity Diagram (WAD) used in (Liu
and Ong,
1999) by complementing the “Customer”
and the “Insurance agent” swim lanes, the start state
and the end state.
Following the rules proposed above, figure 7
shows the UML activity diagram extended, which
expresses the same meaning with the WAD extended
by norms illustrated in (Liu and Ong,
1999) but in a
much simpler and more direct way. In figure 7, the
norm hidden behind the transition pointing to the
activity state “Accept form” can be explicitly
expressed as follows:
whenever an form has been accessed
if criteria are met
then an insurance agent
is permitted
to accept the form
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