Message Passing Programme Development Environment

In a multicomputer system, the computational load among various processors must be balanced. To pass information among various nodes, message-passing technique is used. The programming environment of a multicomputer contains a host runtime system and resident operating system known as Kernel in all the node computers. The host system gives uniform communication among processes without intervention of the nodes, network connection and host workstation.  Host processes are located outsides the nodes. The host environment for hypercube computer at Caltech is a UNIX processor and uses UNIX and language processor utilities to communicate with node processes. The Kernel is separately located in each node computer that supports multiprogramming with an address space confined by local memory.  Many node processes can be created at each node.  All node processes execute concurrently in different physical node or interleaved through multiprogramming within the same node.  Node processes communicate with each other by sending or receiving messages.

he messages can be of a variety of types.  A particular field of all messages can be reserved to represent message type. The message passing primitives are as follows:

• Send (type, length, buffer, node process)
• Receive (type, length, and buffer)

Where type classified the message type, buffer shows location of the message, length specifies the length of the message, and node designates the destination node and process shows process ID at destination node.  Send and receive primitives are used for indicating the sending and receiving processes respectively.  The buffer field of send shows the memory location from which messages are sent and the buffer field of receive indicates the space where arriving messages will be stored.