On 16 Nov 2006, at 01:35, Rick Duley wrote: > My experience of Booch components is that they are subroutines > rather than classes. Even the Ada83 BCs were packages with private Container types and relevant operations; sound like classes to me. The Ada95 BCs use tagged types in their implementation but are still generics from the user's point of view. Of course Java containers tend to rely on everything being an Object, which is much the same thing. I don't use Java so don't know what it is that is OO about the typical use you describe. I suppose if you have an abstract type that provides basic functionality X (eg being a web server, or more likely being an HTTP_Response) you can extend it to provide exactly what your application needs. That's a powerful approach, don't know how many of us have used it.