A worked example
A worked example
In this Chapter we provide a complete worked example of the development of an information model. The initial model specification is taken from an ISO report, TR 9007, which, among other things, describes several means of representing this particular example. The model representations used here are the EXPRESS-G and EXPRESS languages, and this also serves as an introduction to some aspects of the languages. Minor use is also made of EXPRESS-I. For explanatory purposes we do not strictly adhere to the methodology described earlier. The principal difference being that we develop simultaneously both a graphical and a lexical version of the model. The initial model statement for the worked example is given in Section 4.1.1 and 4.1.2 and is taken from ISO TR 9007. In our modeling methodology this would be developed by the modeling team as the initial step in the modeling process. By the time the team is in a position to be as clear on the specification as given in 4.1.2 about the real world aspects of the problem, then the majority of the modeling work has been accomplished. The remaining task, which is what we will be concentrating on, is to formally describe and document the model. The scope of the model to be described has to do with the registration of cars and is limited to the scope of interest of the Registration Authority. The Registration Authority exists for the purpose of: • Knowing who is or was the registered owner of a car at any time from construction to destruction of the car. • To monitor certain laws, for example regarding fuel consumption of cars and their transfer of ownership. There are a number of manufacturers, each with one unique name. Manufacturers may start operation, with the permission of the Registration Authority (which permission cannot be withdrawn). No more than five manufacturers may be in operation at any time. A manufacturer may cease to operate provided he owns no cars, in which case permission to operate lapses. A car is of a particular model and is given a serial number by its manufacturer that is unique among the cars made by that manufacturer.
Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service. Public users can however freely search the site and view the abstracts and keywords for each book and chapter.
If you think you should have access to this title, please contact your librarian.