Something is not quite right, as the ruby client hangs after final request, but it's a start.

zeromq/.gitignore

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+hwserver

zeromq/Makefile

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+CFLAGS += -I. -I/usr/local/include
+LDFLAGS += -lstdc++ -lpthread -luuid -lrt
+
+
+hwserver: hwserver.c /usr/local/lib/libzmq.a
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)

zeromq/hwclient.rb

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+# vim:fileencoding=utf-8
+
+require 'zmq'
+
+def main
+  context = ZMQ::Context.new(1)
+
+  puts "Connecting to hello world server…"
+  requester = context.socket(ZMQ::REQ)
+  requester.connect("tcp://localhost:5555")
+
+  0.upto(9) do |request_nbr|
+    puts "Sending request #{request_nbr}…"
+    requester.send("Hello")
+
+    reply = requester.recv(6)
+    puts "Received reply #{request_nbr}: [#{reply}]"
+  end
+end
+
+
+if $0 == __FILE__
+  main
+end

zeromq/hwserver.c

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+#include <zmq.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+
+int main(void)
+{
+    void *context = zmq_init(1);
+
+    void *responder = zmq_socket(context, ZMQ_REP);
+	printf("Binding server to tcp://*:5555\n");
+    zmq_bind(responder, "tcp://*:5555");
+
+	printf("Starting loop.\n");
+    while(1) {
+        zmq_msg_t request;
+        zmq_msg_init(&request);
+        zmq_recv(responder, &request, 0);
+        printf("Received Hello\n");
+        zmq_msg_close(&request);
+
+        sleep(1);
+
+        zmq_msg_t reply;
+        zmq_msg_init_size(&reply, 5);
+        memcpy(zmq_msg_data(&reply), "World", 5);
+        zmq_send(responder, &reply, 0);
+        zmq_msg_close(&reply);
+    }
+
+    zmq_close(responder);
+    zmq_term(context);
+    return 0;
+}