itaps-parallel Mesh Instances

[Devine, Karen D.]

In yesterday's meeting, Lori asked me to add our understanding of iMesh
instances to the background and terminology section of the combined
document.  I am unable to do so until we come to some agreement on what mesh
instances are and how they are to be used.

Let's start with getting agreement for serial applications.

In the iMesh user guide, I cannot find a definition of what a mesh instance
represents.  To me as a new(ish) ITAPS user, it looks like it represents a
single mesh.  If our interface were a C++ interface, I would say that iMesh
is a class, and that we'd create one iMesh object for each mesh we used in
the application.  Then we'd invoke methods on each iMesh object as needed.
For examples, in a loosely coupled physics implementation on two meshes,
we'd invoke meshOne's methods to do the first set of physics, and meshTwo's
methods to do the second set of physics.

In our C interface, we can't invoke methods on an object.  What we do
instead is what most people do when writing an object-oriented C interface:
they pass the object to the interface functions.  It is like passing C++'s
"this" pointer to C functions.

I think this is a natural way for users of multiple meshes to view the iMesh
instance, and I don't see anything in the documentation to contradict it.  I
also think we need to allow multiple iMesh instances to allow multiple
implementations to be used at the same time via the multiplexer.

Let's get this serial scenario understood before we move on to parallel.

Karen

------ Forwarded Message
From: Mark Miller <miller86 at llnl.gov>
Organization: Lawrence Livermore National Lab
Date: Fri, 16 Nov 2007 00:21:51 -0800
To: "itaps-parallel at mcs.anl.gov" <itaps-parallel at mcs.anl.gov>
Subject: itaps-parallel comments on today's meeting

I think it is important to understand in detail Tim's insistence that
there should be only one iMesh_instance object per 'parallel task'
even to the point of aglomerating multiple different meshes of
an application into that iMesh_instance and then distinguishing
between them via a multiplexer. I think I understand some of his
rationale for this but not all of it. And, I am sure I don't
understand how multiplexing helps as my understanding is that
the multiplexer is the iMesh instance (at least in Jason's example
he sent us).

------ End of Forwarded Message