[ogsa-bes-wg] Re: [jsdl-wg] Questions and potential changes to JSDL, as seen from HPC Profile point-of-view

[Donal K. Fellows]

Marvin Theimer wrote:
> Agreed.  Also, one possibility is to explicitly specify some of the 
> commonly occurring “semi-bound” scenarios, such as “any x86” 
> architecture.  I’m not familiar enough with the CIM world to know if 
> they can provide us with guidance on how to solve the problem in general.

The problem with CIM (certainly up to the most recent release, 2.12) is
that they model processor types as a pair: (enum value, string) with the
string being used only when the enum is "Other". Moreover, the only
matching model that you can have using such a model is exact matching;
for example, there is no concept that "80386" (the string rendering of
value 5 for the CIM_Processor.Family field) is effectively subsumed by
"80486" (value 6). Given that, I'd say that while CIM is a nice catalog
of processor types (particularly given that someone else is maintaining
it ;-)) it's utterly impossible to use for resource selection since the
one thing you can say for sure is that people won't match the processor
types precisely. What we'd need is some kind of partial ordering (or set
of POs, I fear) that allows inexact matching of processor types, but
that is itself quite a bit of work (and it's ongoing work too). And such
relations are not at all clean to describe in CIM either; although
they've got a rich relation model, they're about relating classes and
not values of enumerations. Fixing the model that way would entail a
major change to the CIM core itself I think, and not just defining more
classes on top. Either that or changing the specification of the
processor part of CIM to model processor families as classes, which
would be very disruptive to what is a pretty static (and hence widely
deployed) of CIM.

And IIRC, CIM's OS types (CIM_OperatingSystem.OSType) suffer from the
same problem. (If I have a binary that works on Win2k, I'd expect it to
be fine on WinServer2003 for example, but that's not information
captured within CIM.)

CIM does description of what is out there well. But it's a very poor
base for anything with much richer semantics than equality. I hope this
message explains why adequately.

Donal.