Re: modules and components

[email protected] wrote:

> On Tuesday 10 December 2002 11:39, [email protected]
> wrote:
> > I haven't well understood the difference between modules and components
> > Can you explain me the differences with an exsample?
> > Piercarlo
>
> They are very closely related. Depending on who you ask (and when you ask) you
> might hear that a module is a generic term for a unit of functionality, while
> a component is a CORBA enabled module, or something that comes very close to
> it (nameserving seems obligatory to qualify)
>
> example of a module : a TrajectoryGenerator class implementing one interface.
> example of a component :  a nameserved Robot, offering lots of services (read
> lots of interfaces)
>
> Peter.

Hi,

A nice definition of component is the following one (the OMG has one also):

"A software component is a unit of composition with contractually specified
interfaces and explicit context dependencies only. A software component can be
developed independently and is subject to composition by third parties"
(Szyperski, WCOP 1996).

The important thing is the second sentence which puts a focus on late
composition. This is exactly what makes the difference between the CORBA object
model and the CORBA component model. The latter adds tools for late composition
on top of distributed objects.

The term module in this context normally refers to a unit of functionality (as
explained by Peter) and this might be a set of objects, a library or whatever.

Christian


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Christian Schlegel
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