Here is a simple client:

#include <err.h>
#include <stdio.h>
#include <stdlib.h>

#include <ipc/echo.h>

int main(int argc, char *argv[]) 
{
	int result, response;

	result = echo("hello world");
	if (result == NULL)
		errx(1, "IPC error: %s", ipc_strerror());
	
	puts(result);

	exit(EXIT_SUCCESS);
}