The second platform that supports the tightly-coupled computations in MAPPER is MPWide communication library for distributed message passing . MPWide is trivial to install and allows distributed applications to obtain superior wide area communication performance, compared to approaches such as cross-site MPI or single-stream TCP communication libraries. MPWide is currently used to enable the coupling in a multiscale scenario of intracerebral bloodflow, where the performance and responsiveness of the coupling communications is particularly important. One of the first steps that was taken here is implementing MPWide APIs for FORTRAN and Python applications. Further more, the MPWide is being integrated into the MUSCLE Transport Overlay (MTO), thereby it will greatly enhance the cross-site communication performance of MUSCLE.
The latest release of MPWide can be found here.
 D. Groen, S. Rieder, P. Grosso, C. de Laat and P. Portegies Zwart. A light-weight communication library for distributed computing. Computational Science and Discovery, vol. 3, no. 015002 (Aug 2010).