I haven't seen that program.
but you're looking into IPC ( inter-process communication ). There are tons of books on this. A very good one is the Stevens.
IPC falls under many catagories. From most effecient but difficult to program Memory mapped IO ( mmap ), where separate process share memory by sharing a region of memory. To very simple UNIX domain sockets, where the processes share a special socket file to exchange information. And finally UNIX PIPES, where file descriptors and normal file read()/write() functions are used to share information.