[Tutor] definition of a library

[alan.gauld@bt.com]

> > sometimes important distinction (and one not recognised 
> > by UML for those who care :-).
> What you call modules is named packages in UML. Libraries, 
> respectively, are components in UML. 

That's what I initially assumed but at a seminar with Grady 
Booch when I asked him he defined components as being 
*files* in C++ terms. In the old Booch notation there 
was a concept of subsystem and libraries could be 
represented there. 

Unfortunately UML has rationalised(sic!) the physical 
notation to the point where we have to make do with generic 
symbols like component which can represent several 
radically different physical entities. Thats what I meant 
by "not supporting" - there's nothing explicit, only 
overloading the component symbol.

> physical structure. The difference is not very subtle, IMHO :)

Personally I don't think so either but in discussions with
various CASE tool vendors plus Grady it would seem that the 
significance of the difference is not seen as high. (And 
incidentally I've even had CASE tool folks tell me that a 
package is a library which is definitely wrong!)

Alan g.