WebTrafficMonitor.cpp

00001 // Example of a simple website hits/signup traffic monitor to drive 
00002 // a display (e.g. servo or panel meter) and indicator (e.g. bell, solenoid)
00003 // based on responses from a webserver
00004 // http://mbed.org
00005 
00006 #include "mbed.h"
00007 #include "EthernetNetIf.h"
00008 #include "HTTPClient.h"
00009 #include "Servo.h"
00010 
00011 #define SIGNUPS_URL "http://url-returning-signups-int"  // number of signups since last checked
00012 #define HITS_URL "http://url-returning-hits-int"        // number of hits/sec since last checked
00013 #define HITS_MAX 1000                                   // scale max hits/sec
00014 
00015 EthernetNetIf eth;
00016 HTTPClient http;
00017 
00018 DigitalOut bell(p12);
00019 Servo meter(p21);
00020 
00021 // ding a bell (fire a digital out driving a solenoid)
00022 void ding() {
00023     bell = 1;
00024     wait(0.25);
00025     bell = 0;
00026 }
00027 
00028 // fetch a integer from a url
00029 int get_result(char *url) {
00030     HTTPText txt;
00031     HTTPResult r = http.get(url, &txt);
00032 
00033     if(r != HTTP_OK) {
00034         printf("Error [%d] fetching url [%s]\n", r, url);
00035         return -1;
00036     }
00037     
00038     printf("Response [%s] from url [%s]\n", txt.gets(), url);
00039     int v = 0;
00040     if(sscanf(txt.gets(), "%d", &v) != 1) {
00041         printf("Could not convert value to int\n");
00042     }
00043     
00044     return v;
00045 }
00046 
00047 int main() {
00048     printf("Setup the network...\n");
00049     EthernetErr ethErr = eth.setup();
00050     if (ethErr) {
00051         error("Error %d in setup\n", ethErr);
00052     }
00053     printf("OK!\n");
00054 
00055     while (1) {
00056         int hits = get_result(HITS_URL);
00057         int signups = get_result(SIGNUPS_URL);
00058 
00059         printf("hits = %d, signups = %d\n", hits, signups);
00060         
00061         // ding for every signup since last request
00062         for(int i=0; i<signups; i++) {
00063             ding();
00064             wait(0.5);
00065         }
00066     
00067         // set the servo based on hits/sec
00068         meter = (float)hits / (float)HITS_MAX;            
00069    }
00070 }