= Coupling MPI codes using MUSCLE =
== Example Application ==
A new
== MPI Kernels as dynamic libraries ==
This approach follows the original MUSCLE philosophy that relay on using Java Native Interface/Access mechanism to integrate C/C++ codes as MUSCLE kernels.

A new method, `public void executeDirectly()`, is available in the `CaController` class. Only this method is called instead of normal MUSCLE routines on the processes with non-zero rank. Process with rank 0 is started in the usual way. Portals cannot be attached to slave processes (i.e. to the processes with non-zero rank). The `executeDirectly` method default implementation calls by default `execute()`.
=== Compilation ===
=== Running ===

=== Limitations ===
* Any MUSCLE API routine may be **ONLY** called by the rank 0 process. If you need any parameters to be available for the all MPI processes use `MPI_Bcast` function, for e.g. (as in provided  example):
{{{
void Ring_Broadcast_Params(double *deltaE, double *maxE)
{
        assert( MPI_Bcast(deltaE, 1, MPI_DOUBLE, 0, MPI_COMM_WORLD) == MPI_SUCCESS);
        assert( MPI_Bcast(maxE, 1, MPI_DOUBLE, 0, MPI_COMM_WORLD) == MPI_SUCCESS);
}
}}}
* A separate Java Virtual Machine is started for every MPI process what increase significally the memory footprint of the whole application.
* Many MPI implementations exploits low level optimization techniques (like Direct Memory Access) that may cause crash of Java Virtual Machine.
* Using MPI to start many  Java Virtual Machines, which loads some native dynamic-link library that later calls MPI routines is something that most people rarely do. In case of problems you might not found any help (you have been warned! ;-).

== MPI Kernels as standalone executables ==
=== Compilation ===
=== Running ===

=== Limitations ===
* Any MUSCLE API routine may be **ONLY** called by the rank 0 process. If you need any parameters to be available for the all MPI processes use `MPI_Bcast` function, for e.g. (as in provided  example):
{{{
void Ring_Broadcast_Params(double *deltaE, double *maxE)
{
        assert( MPI_Bcast(deltaE, 1, MPI_DOUBLE, 0, MPI_COMM_WORLD) == MPI_SUCCESS);
        assert( MPI_Bcast(maxE, 1, MPI_DOUBLE, 0, MPI_COMM_WORLD) == MPI_SUCCESS);
}
}}}