OOA—Analysis and Mission - Programming GPS and OpenStreetMap Applications with Java - page 27

knowledge. The challenge (and risk) is to identify and give meaning to the
information.
Before starting the development of a RealCar , for example, search en-
gines could find expressions and objects used around a car. If language
and knowledge are needed to create RealObject s, it would be desirable
to automate a preselection process with a RealObjectGenerator<RealCar> |
software that would collect all scientific facts about cars and their semantic
context (as connectors to other objects).

3.4 Gathering Information

The semantic net is supports creative thinking, but project vocabulary is
not project knowledge.
Object orientation suggests to gather domain knowledge, in order to
design objects similar to real ones. In addition to the gravitational formula,
it helps to know that gravity is tied to every mass. Knowing this, the
architect has to make sure that the gravity law is always applied, wherever
the mass attribute is added to an object.
The first topic (see page 35) we will need to gather material for will be
space and time, the prerequisite to describe motion (= space/time). The
globe has a coordinate system to find any place on its surface. However,
spatial coordinates are not very practical to describe physical laws of mo-
tion. These are usually expressed in linear Cartesian coordinates. In this
case, the main task of gathering material is to answer the question: How
can global positions be converted into linear Cartesian coordinates?
Gathering information is not restricted to only the beginning of a project.
For new software development where large user groups are involved, it is
often worth the effort to conduct interviews or send out questionnaires on
a regular basis. Not only does the software itself evolve, but also the per-
ception of usability can change over time and the users, not the developers,
are the experts.

3.5 Data Dictionary

The semantic net is a useful exercise, but still leaves room for interpreta-
tion. Like an appendix or a glossary, project papers should be based on
a data dictionary, which should be maintained regularly to reflect current
project status. A great maintenance tool to prevent confusion and improve
communication is a wiki software accessible to the entire development team.
A data dictionary should establish and define the major vocabulary of a
project in a common context. Since this project is about the vision of a real-
world simulation, one might start with an entry for the term simulation.