A low-level communication library for Java HPC

In this chapter we describe the low-level communication library, mpjdev, we introduced for HPJava. This library is developed with HPJava in mind, but it is a standalone library and could be used by other systems. We start this chapter with brief introduction of mpjdev. Detailed information on the mpjdev buffer APIs and communication APIs follows. We will describe different types of buffer operations dealing with both contiguous and non-contiguous data, and various communication methods like blocking and non-blocking communications. A following section discusses how actual data is stored into the message buffer. We also describe issues in four different implementations. An implementation based on native MPI, a pure-Java multithreaded implementation, and platform specific LAPI implementation are already developed. There is also one proposed Jini implementation.