Add weather client/server examples for Felix.

examples/Felix/wuclient.flx

@@ -0,0 +1,56 @@
+//
+//  Weather update client
+//  Connects SUB socket to tcp://localhost:5556
+//  Collects weather updates and finds avg temp in zipcode
+//
+open ZeroMQ;
+
+fun parse_int(s:string,var i:int) = {
+  var acc = 0;
+  while s.[i] \in "0123456789" do
+    acc = acc * 10 + s.[i].ord - "0".char.ord;
+    ++i;
+  done
+  return i,acc;
+}
+
+fun parse_space(s:string, i:int)=> i+1;
+
+fun parse_weather(s:string) = {
+  var i = 0;
+  def i, val zipcode = parse_int (s,i);
+  i = parse_space(s,i);
+  def i, val temperature = parse_int (s,i);
+  i = parse_space(s,i);
+  def i, val relhumidity= parse_int (s,i);
+  return zipcode, temperature, relhumidity;
+}
+
+var                  context = zmq_init 1;
+
+                     //  Socket to talk to server
+                     println "Collecting updates from weather server...";
+var                  subscriber = context.mk_socket ZMQ_SUB;
+zmq_validate$        subscriber.connect "tcp://localhost:5556";
+
+                     //  Subscribe to zipcode 100
+                     filter := if System::argc > 1 then System::argv 1 else "1001" endif;
+zmq_validate$        subscriber.set_sockopt$ zmq_subscribe filter;
+
+                     //  Process 100 updates
+var                  total_temp = 0;
+for var update_nbr in 0 upto 99 do
+                     e,s := subscriber.recv_string;
+zmq_validate$        e;
+
+                     zipcode, temperature, relhumidity := parse_weather s;
+                     total_temp += temperature;
+done
+                     println$ 
+                       f"Average temperature for zipcode '%S' was %d C\n"$
+                       filter, total_temp / update_nbr
+                     ;
+
+zmq_validate$        subscriber.close;
+zmq_validate$        context.term;
+

examples/Felix/wuserver.flx

@@ -0,0 +1,22 @@
+//
+//  Weather update server
+//  Binds PUB socket to tcp://*:5556
+//  Publishes random weather updates
+//
+open ZeroMQ;
+                     //  Prepare our context and publisher
+var                  context = zmq_init 1;
+var                  publisher = context.mk_socket ZMQ_PUB;
+zmq_validate$        publisher.bind "tcp://*:5556";
+zmq_validate$        publisher.bind "ipc://weather.ipc";
+
+while true do
+                     //  Get values that will fool the boss
+                     zipcode     := #rand % 1000+1000;
+                     temperature := #rand % 80 - 20; // Oztraila mate!
+                     relhumidity := #rand % 50 + 10;
+
+                     //  Send message to all subscribers
+  var                update = f"%03d %d %d" (zipcode, temperature, relhumidity);
+  zmq_validate$      publisher.send_string update;
+done