Ethernet XML (find)

International Português
1

Olá,

Estou a tentar obter a temperatura (e mais tarde outras informações) do site Weather Underground

Basicamente tenho a informação toda em XML e tento procurar a variável que pretendo mas o resultado é sempre negativo, nunca a encontra.

Exemplo de código obtido:

<response>
<version>0.1</version>
<termsofService>
http://www.wunderground.com/weather/api/d/terms.html
</termsofService>
<features>
<feature>conditions</feature>
</features>
<current_observation>
<image>
<url>
http://icons-ak.wxug.com/graphics/wu2/logo_130x80.png
</url>
<title>Weather Underground</title>
<link>http://www.wunderground.com</link>
</image>
<display_location>
<full>Rome, Italy</full>
<city>Rome</city>
<state/>
<state_name>Italy</state_name>
<country>IY</country>
<country_iso3166>IT</country_iso3166>
<zip>00000</zip>
<magic>1</magic>
<wmo>16240</wmo>
<latitude>41.90000153</latitude>
<longitude>12.47999954</longitude>
<elevation>95.00000000</elevation>
</display_location>
<observation_location>
<full>
Roma Ardeatina - Appia Antica Caffarella, Rome, Lazio
</full>
<city>Roma Ardeatina - Appia Antica Caffarella, Rome</city>
<state>Lazio</state>
<country>Italy</country>
<country_iso3166>IT</country_iso3166>
<latitude>41.863281</latitude>
<longitude>12.502114</longitude>
<elevation>140 ft</elevation>
</observation_location>
<estimated></estimated>
<station_id>IROMAROM3</station_id>
<observation_time>Last Updated on March 7, 2:09 AM CET</observation_time>
<observation_time_rfc822>Fri, 07 Mar 2014 02:09:21 +0100</observation_time_rfc822>
<observation_epoch>1394154561</observation_epoch>
<local_time_rfc822>Fri, 07 Mar 2014 02:09:22 +0100</local_time_rfc822>
<local_epoch>1394154562</local_epoch>
<local_tz_short>CET</local_tz_short>
<local_tz_long>Europe/Rome</local_tz_long>
<local_tz_offset>+0100</local_tz_offset>
<weather>Clear</weather>
<temperature_string>47.3 F (8.5 C)</temperature_string>
<temp_f>47.3</temp_f>
<temp_c>8.5</temp_c>
<relative_humidity>36%</relative_humidity>
<wind_string>Calm</wind_string>
<wind_dir>North</wind_dir>
<wind_degrees>0</wind_degrees>
<wind_mph>0.0</wind_mph>
<wind_gust_mph>0</wind_gust_mph>
<wind_kph>0.0</wind_kph>
<wind_gust_kph>0</wind_gust_kph>
<pressure_mb>1017</pressure_mb>
<pressure_in>30.04</pressure_in>
<pressure_trend>+</pressure_trend>
<dewpoint_string>22 F (-6 C)</dewpoint_string>
<dewpoint_f>22</dewpoint_f>
<dewpoint_c>-6</dewpoint_c>
<heat_index_string>NA</heat_index_string>
<heat_index_f>NA</heat_index_f>
<heat_index_c>NA</heat_index_c>
<windchill_string>47 F (8 C)</windchill_string>
<windchill_f>47</windchill_f>
<windchill_c>8</windchill_c>
<feelslike_string>47 F (8 C)</feelslike_string>
<feelslike_f>47</feelslike_f>
<feelslike_c>8</feelslike_c>
<visibility_mi>N/A</visibility_mi>
<visibility_km>N/A</visibility_km>
<solarradiation>0</solarradiation>
<UV>-1</UV>
<precip_1hr_string>0.00 in ( 0 mm)</precip_1hr_string>
<precip_1hr_in>0.00</precip_1hr_in>
<precip_1hr_metric>0</precip_1hr_metric>
<precip_today_string>0.00 in (0 mm)</precip_today_string>
<precip_today_in>0.00</precip_today_in>
<precip_today_metric>0</precip_today_metric>
<icon>clear</icon>
<icon_url>http://icons-ak.wxug.com/i/c/k/nt_clear.gif</icon_url>
<forecast_url>
http://www.wunderground.com/global/stations/16240.html
</forecast_url>
<history_url>
http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=IROMAROM3
</history_url>
<ob_url>
http://www.wunderground.com/cgi-bin/findweather/getForecast?query=41.863281,12.502114
</ob_url>
</current_observation>
</response>

No Arduino estou a usar o seguinte:

#include <SPI.h> 
#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
char serverName[] = "api.wunderground.com";
EthernetClient client;

void setup()
{
  Serial.begin(9600);
  if(Ethernet.begin(mac) == 0) { 
    Serial.println("Failed to configure Ethernet using DHCP");  
    while(true)   // no point in carrying on, so stay in endless loop:
      ;
  }
  delay(1000); // give the Ethernet shield a second to initialize

  Serial.println("connecting...");
}

void loop()
{
  if (client.connect(serverName,80)>0) {

    client.println("GET /api/MyKey/conditions/q/Italy/rome.xml HTTP/1.0");  
    client.println();
  }
  else {
    Serial.println(" connection failed");
  }
  if (client.connected()) {
     if(client.find("<temp_c>") )
     {
        int temperature = client.parseInt();
        Serial.print("Temperature is ");  
        Serial.println(temperature);
     }
    else
      Serial.println("Could not find temperature field");
     if(client.find("<relative_humidity>") )      
     {
        int humidity = client.parseInt(); 
        Serial.print("Humidity is ");  
        Serial.println(humidity); 
     }
     else
       Serial.println("Could not find humidity field");
  }
  else {
    Serial.println("Disconnected");
  }
  client.stop();
  client.flush();
  delay(60000); // wait a minute before next update
}

Basicamente queria ver o valor de **temp_**c e relative_humidity, consegue conectar-se ao site mas depois devolve o erro de que não as encontra. Estou a fazer algo de errado?

2

Quem dera se fosse tão simples.. Primeiro você tem que ler caracter por caracter, para depois manipular.

Segue um método que fiz, baseados em exemplos da net, o clienteIP é o seu client

// tamanho do buffer HTTP, seu caso deverá ser bem maior, pois o xml é grande
#define REQ_BUF_SZ   70
char HTTP_req[REQ_BUF_SZ] = {0}; //buffered HTTP request stored as null terminated string
char req_index = 0;              // index into HTTP_req buffer

void getServerData() {
    int numT=0;
    //esperar dados servidor
    while((!clientIP.connected() || !clientIP.available()) && numT<15000) {
      delay(1); 
      numT++;
    }
    Serial.println();
    
    numT=0;
    while ((clientIP.connected() || clientIP.available()) && numT<1000) {
      char c = clientIP.read();
      if (req_index >= (REQ_BUF_SZ - 1)) req_index=0;
      if (req_index < (REQ_BUF_SZ - 1)) {
          HTTP_req[req_index] = c;          // save HTTP request character
          req_index++;
      }       
      Serial.print(c);
      numT++;
    }
    
    Serial.println(F("FIM"));
    
    Serial.println(F("Desconectando"));
    clientIP.stop();      
}

depois para verificar os valores pode user o seguinte código

if (StrContains(HTTP_req, "<tag_xml>")) {
  //ler o buffer e encontrar a variável.. Você pode criar um método baseado no abaixo para fazer isso.
}

char StrContains(char *str, char *sfind)
{
    char found = 0;
    char index = 0;
    char len;

    len = strlen(str);
    
    if (strlen(sfind) > len) {
        return 0;
    }   
    
    while (index < len) {        
        if (str[index] == sfind[found]) {
            found++;
            if (strlen(sfind) == found) {
                return 1;
            }
        }
        else {
            found = 0;
        }
        index++;
    }
    return 0;
}

Espero que isso te ajude.

3

Parecido com o seu:
http://forum.arduino.cc/index.php/topic,39023.0.html

4