Re: Statement on backwards compatibility?


"Tony Proctor" <tony_proctor@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:%23t3XVvy%23FHA.532@xxxxxxxxxxxxxxxxxxxxxxx
> Does anyone know of a link that describes Microsoft's official stance on
> backwards compatibility?
>
> The terms upwards and backwards compatibility are a little ambiguous, and
> depend on which way you're looking through the telescope. In this context, I
> refer to the expectation that products compiled on a higher O/S version can
> be distributed and run on older O/S versions.
>
> Most people would expect upwards compatibility. For instance, if you
> compiled a well-behaved program under W2K then it should run under W2003.
> Few people who have been involved in large-scale software development,
> across different platforms (e.g. UNIX), would expect the latter. For
> instance, if a "versioned" struct had been changed in size then older
> versions of the O/S may not know how to handle it.
>
> I personally would not expect backwards compatibility (as defined above)
> because I've seen the issues that can arise. However, I'm looking for a link
> to any statement on the subject in relation to the Windows O/S

You're looking through the telescope in the wrong direction. Backward
compatibility is when the newer version of the OS will still properly run
programs written for the older version. This is a concept that Microsoft
believes in and takes to extremes, while Apple scoffs at it.

You can not expect the reverse. You can write programs which will run on
older versions by restricting the APIs you use to the ones supported by the
older versions, but then you're taking advantage of backward compatibility.
You can also write programs which are smart enough to run an multiple
versions. More then this isn't possible because it would require older
versions to be aware of the capabilities of newer versions (where did I put my
time machine?).

--

-GJC [MS Windows SDK MVP]
-Software Consultant (Embedded systems and Real Time Controls)
- http://www.mvps.org/ArcaneIncantations/consulting.htm
-gchanson@xxxxxxxx


.