Re: Use model and compliance

Hi Brian, Shabtay, and John,

you have some good comments.  My main concern is the labelling
of the subsets as SCE-MI 1 (or SCE-MI 1.1) and SCE-MI 2.  This
can lead to the at best imprecise and at worst wrong impression
that SCE-MI 2.x is purely DPI.  I also like the labels Brian
came up with (message passing and function call) and agree with
John that we should be using them instead of SCE-MI 1.x and
SCE-MI 2.x.  After all, they are both part of SCE-MI 2 and
it is not even correct to say that the message passing subset
is equivalent to SCE-MI 1.1 as it has been updated since SCE-MI 1.1.
That is, if one restricted oneself to the message passing subset
of SCE-MI 2.x, it is not guarenteed that the application will
be portable to a strict SCE-MI 1.1 implementation.

Another issue that John hints at is the issue of what does it
mean for a model to be compliant with the standard.  I am not
sure we can fully define that as we have not restricted and
defined the modelling subset.  This means that although a model
may use the SCE-MI API in a compliant way it is still not
guaranteed to be portable to another compliant implementation
as it may be using features outside of the SCE-MI API that
are not portable, e.g., language constructs that are only
synthesizable on some platforms.

Also, I am not happy with the distinction between the message
passing and function call interfaces in terms of the leeway
an implementation is given for implementing it and adding
extensions.  Quoting from Brian:

   With the message passing use model, all implementations must
   implement each and every feature of the standard in order to
   be deemed compliant with the standard.

My point is that this is true of the *whole* standard.  You
must implement all features of the standard to be compliant.
There are no optional features.  There are areas that have
undefined behavior especially in the function call subset,
but that is different.

So the question is this in my mind: is an implementation
that includes extensions still compliant?  In some sense
this is meaningless since we have no way of checking this.
Even if we had a compliance test suite we would be in trouble
unless the test suite was extremely clever.  I think it is
not possible in the extreme since you cannot think of every
possible extension and check that it is *not* implemented.

Per



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