Re: how many programmers to change a lightbulb ?

[Marin Condic <condicma@bogon.pwfl.com>]

G wrote:

> Things like - when someone designs a major software project (I have been
> looking
> at the documents on domain analysis and other things at SEI) - it
> appears as though the project is broken into teams - and each team need
> only know about as much about the other team's work as they do to know
> where what they are designing interacts with the other modules and
> components of the system, that is - what contracts are being resolved.
> As long as they return what is required to the system in the most
> efficacious manner, everyone is happy.
>
> Is that right (however simple it may be) ?  Won't there be problems with
> geographically remote teams of programmers doing things separately such
> that certain discontinuities might emerge with (the
> compatibility/interoperability issues of) the various modules they
> design ?

In my experience with large software development efforts in Ada, you
definitely get advantages in designing the interfaces between functional
groups early on. To a large extent, it does allow developers of different
subsystems to proceed independently. However, there is never a panacea which
is going to make everything run flawlessly. It all goes back to the Tower of
Babel. Or maybe Adam biting the apple.

Inevitably, as a project progresses, different groups are going to discover
things which make redesigning the interfaces necessary. Maybe just little
tweaks - sometimes major overhauls. Independent development gets disturbed
at that point. There will also come points in time when everybody has to
synchronize up because you have to pull the various pieces together and
subsystem A won't function correctly unless subsystem B is up and working as
well. So team A is dependent on team B finishing their work.

Eventually, you have to integrate everything and clearly defined interfaces
help to make this less painful. But there is always functionality behind the
interfaces and that requires coordination - thus making teams less
independent. Just because the plug and the socket match, doesn't mean that
you get the voltage you expected! :-)

MDC
--
Marin David Condic
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