The "hints" or "info" structure is a way to provide extensibility
to the MPI API. It also allows vendors to meet the requirements of
the standard while only supporting the features which are economically
feasible. Some vendors could care less about piofs or anything besides
local disk. Why force them into parsing an encoding of a resource from
a data set (file) name?
Meanwhile, other developers would like to allow their MPI I/O file handles
to work on piped standard input and arbitrary sockets.
A mechanism is also desirable for specifying resource access patterns
and local resource conditions (e.g., hint: this local disk can be used
for cache).
No standards exist in this area for the MPI Forum to build on. Instead
of trying to start N new standards efforts, we can supply "info" as
a means for researchers to experiment with new computational paradigms.
- Richard