%T Dynamicity through Occam and TDS
%A  D. Millot,  J. Vautherin
%E  J. Wexler
%B OUG\-11: Developing Transputer Applications
%X A parallel program running on a parallel machine involves a
   logical network of processes and a physical network of
   processors. When both networks are known at design time, a
   static mapping of the logical network on the physical one
   can take place. Dynamicity arises when one of the networks
   is not entirely determined before execution starts. This can
   happen for instance when the logical network involves
   dynamic creation of processes, or when the physical topology
   cannot be defined at design time (this is the case in a
   multi\-user context, as the configuration a user gets is
   affected by the other users\[rs] computations, or when the
   programmer wants to develop a generic program that can be
   executed on any physical topology).When using Occam to
   design a network of processes that has to be mapped on
   transputers, things have to be decided before execution
   starts :\-  the network of processes should be composed of
   an explicitly bounded number of processes due to the fact
   that, unlike CSP, Occam does not allow recursion,\-  the
   topology of the transputer network should be known, for
   processes are explicitly mapped onto processors. One has to
   investigate the physical topology in order to write the
   configuration statements, and a change in the topology
   entails modifications in these statements. An application is
   therefore dedicated to a configuration. It would
   nevertheless be very attractive to design software that
   could run on an unidentified topology, trying to make the
   best of available processors. Such software has to realize a
   dynamic placement and therefore includes a phase supposed to
   investigate the configuration, load the different codes on
   the appropriate processors, then dynamically start their
   execution.Our aim is to develop suitable tools to write that
   kind of application. As a first step, we investigate the
   potentiality of Occam and TDS in this field.