A football on a use case diagram represents a use case.
A use case (rhymes with "juice case", not with "ewes case") is a single way that the system is used (ewes'd) by an initiating actor (aka primary actor, often a user (ewes'er)). It is modelled under eweML in a wide variety of ways. In EA, it is one of those footballs with a whole truckload of descriptive gumph. Some of the gumph is structured, some not so.
A use case diagram is a picture of a collection of one or more use case footballs and possibly some stick people, probably with some lines of various sorts between them. The use case diagram is produced by the modeller to either solve a problem he/she is having conceptualising what the system is doing or is to do, or its to communicate some or all of what a system is doing/is to do between the modeller and some other sentient being.
Just like showing a cow a picture of a milkshake will not induce it to milk itself, showing a meaningless mess of visio clip art pictures of people, trucks and PC's to a programmer will not get you the despatch system you want. So a bunch of guys got together and decided to create a visual modelling language, called eweML, where everything has a strict and precise meaning ...... to the cogniscenti anyway.
Because it has such precise meaning, I'm afraid that those big jargon words are necessary to explain the
precise syntactical and semantic nuances. oh bugger, what precisely the footballs and stick people mean.
bruce
sorry, its friday here!
