//
// Weather update client
// Connects SUB socket to tcp://localhost:5556
// Collects weather updates and finds avg temp in zipcode
//
open ZMQ;
fun parse_int(s:string,var i:int) = {
var acc = 0;
while s. \in "0123456789" do
acc = acc * 10 + s..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;
subscriber.connect "tcp://localhost:5556";
// Subscribe to zipcode 100
filter := if System::argc > 1 then System::argv 1 else "1001" endif;
subscriber.set_opt$ zmq_subscribe filter;
// Process 100 updates
var total_temp = 0;
for var update_nbr in 0 upto 99 do
s := subscriber.recv_string;
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
;
subscriber[[span style="color:#666666"]].close;
context[[span style="color:#666666"]].term;