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Bowen, 1996) have been proposed to address the
later-phase of software development, which are im-
portant for specifying precise requirements, focusing
on consistency and completeness issues etc. They are
mostly designed to work in the design phase. We
argue that formal methods lack features for model-
ing the rationale behind the various design decisions
taken during the early phase of requirements analysis.
This paper describes a methodology for the com-
bined use of i* framework (Yu, 1997) and the Z no-
tation (Bert et al., 2003; Bowen, 1996; Spivey, 1992)
for requirements engineering. This approach incorpo-
rates the advantages of i* framework for early-phase
RE like modeling different alternatives of the desired
system, easy requirements modifications etc and then
continues specifying requirements in Z using advan-
tages of mature formal method like powerful means
of specifying precise requirements, better tool sup-
port, facility of verification etc. We can also claim
that i* adds value to the Z formal method. Using Z
specification schemas, we are in a position to express
properties that are not restricted to the current state of
the system, but also to its past and future history. The
approach is based on describing a one-to-one map-
ping of the i* framework into the Z notation. This
mapping is used to formalize the i* framework with-
out incorporating any additional information. Further
refinement is done to this process by using concealed
additional information from i* framework and inte-
grating in Z schemas. This requires further investi-
gation but we have explained this refinement with the
help of simple examples. Some approaches have been
proposed (Fuxman et al., 2001; Wang and Lesprance,
2001) suggesting the use of i* framework for later
phases of software development.
The remainder of this paper is structured as fol-
lows. Section 2 describes Emergency Flood Res-
cue Management Case Study. It also explains agent-
oriented conceptual modelling concepts using i* no-
tation along with a brief introduction to Z. Section 3
concentrates on explaining the mapping of i* mod-
els into Z schemas. Steps explaining further informa-
tion refinement with examples are also discussed in
this section. Section 4 discusses some lessons derived
from the real-life conceptual modelling exercise. Sec-
tion 5 presents concluding remarks.
2 CASE STUDY: FLOOD RESCUE
MANAGEMENT
This paper presents a case study based on a collab-
orative project to build a comprehensive enterprise
model for an emergency services agency (ESA). The
case study concentrates on a key function of the ESA:
managing flood rescue and evacuation operations.
The ESA is responsible for managing diverse emer-
gency situations. The case study deals with an event,
which can be described in many different ways, but
from an ESA perspective the event is definitely a flood
response operation. The timing of the emergency re-
sponse is critical in these scenarios. The ESA is the
agency chosen to deal with these kinds of situations
since it has the expertise and appropriate resources to
deal with the threat.
During the emergency situation described above, at
ESA Emergency Coordination Centre is formed and
the Coordinator (ECCC) heads it. The nominated Co-
ordinator is the person in charge of the overall emer-
gency coordination. The first action taken by the co-
ordinator is to activate the Emergency plan partially
or fully depending on the situation. The main func-
tion of the coordinator is to bring together elements
of the organization together to ensure effective emer-
gency management response and is primarily con-
cerned with the systematic planning and application
of resources (manpower and equipment). He is re-
sponsible for the acquisition of additional resources
requested by different Field Control Centre Coordi-
nator(FCCC). His other responsibilities are to collect
and assess field information so that he can coordinate
the rescue and evacuation operation in a more effec-
tive and efficient manner. Other significant activities
are to analyze weather forecast supplied by weather
bureau and forward the analyzed forecast to the con-
cerned FCCC with his comments/observations.
Field Control Centre is a facility, where the FCCC
is located, near the scene of an emergency to facili-
tate better control and management of the emergency.
FCCC is primarily responsible for proficiently man-
aging the rescue and evacuation operation in the flood
affected area. He is also responsible for publicizing
evacuation routes for the community, manages volun-
teers and available resources at his disposal in most
optimal way.
The other people involved in the case study are Call
Taking Supervisor/System, Volunteers/Emergency
Workers, Community and Weather Bureau. Call
Taking Supervisor/System is responsible for man-
aging/handling calls from the affected people, clas-
sifying/prioritizing them and forwarding calls to
concerned authorities for further action. Volun-
teers/Emergency Workers are very important actors
in the whole emergency situation. They are trained
in all aspects of rescue operation. They are proficient
in general rescue, providing first aid, operating com-
munication equipment, map reading and navigation,
flood rescue boat operations, giving storm safety ad-
vice, provision of essentials to people cut off by flood
waters etc. Community actors in our case study are
people who are affected by the flood. They are the
people who are living in the flood-prone area. They
are concerned about many issues and would like to
A CASE STUDY OF COMBINING I* FRAMEWORK AND THE Z NOTATION
193