Using REST for communication between AVR and Linux

I changed my code on my previous post to use REST as a way to communicate between Arduino and Linux. REST is basically a web server running on the linux side which allows access to key/value pairs via web or through serial from Arduino. In particular I am using this now for sending the info about the song that is playing. From my python script I am calling curl to POST the info to the REST website and from Arduino I am doing Bridge.get calls to receive the data.

Here is the new python script:

from __future__ import print_function

import urllib
import urllib2

import subprocess

import sys

from grooveshark import Client

from grooveshark.classes import Radio

client = Client()

client.init()

cmdargs = str(sys.argv)

url_name='http://localhost/data/put/songName/'

url_artist='http://localhost/data/put/songArtist/'

url_album='http://localhost/data/put/songAlbum/'

for song in client.radio(sys.argv[1]):

    

    song_name = unicode(song.name).encode("utf-8")

    song_artist_name = unicode(song.artist.name).encode("utf-8")

    song_album_name = unicode(song.album.name).encode("utf-8")

    print(song_name)

    print(song_artist_name)

    print(song_album_name)

    url_name_curl = url_name + urllib.quote(song_name)

    urllib2.urlopen(url_name_curl)

    url_artist_curl = url_artist + urllib.quote(song_artist_name)

    urllib2.urlopen(url_artist_curl)

    url_album_curl = url_album + urllib.quote(song_album_name)

    urllib2.urlopen(url_album_curl)

    sys.stdout.flush()

    subprocess.call(['mpg123', song.stream.url])

UPDATE:

There is a pycurl library that I could have used instead (and there seem to be other alternatives, I am just not a python expert), but this seemed quicker to implement at the time. Will find an alternative... 
I am using urllib2 to do the POST requests to the REST website. Originally I was using curl (running it in a subprocess) but urllib2 avoids calling a separate process.

Important thing is to remember calling urllib.quote on the text to POST, as you will need to convert special characters to "%XX" to make it a valid URL.

On the Arduino side I am only getting the song name, but it is enough to get the idea of how this is done. This is how my sketch looks like now:

#include <FileIO.h>

#define    GENRE_NONE             0

#define    GENRE_ROCK             12

#define    GENRE_BLUES            230

#define    GENRE_ELECTRONICA      67

#define    GENRE_CLASSICROCK      3529

#define    GENRE_INDIE            136

#define    GENRE_METAL            17

int stations[] = { GENRE_NONE,

    GENRE_ROCK,

    GENRE_BLUES,

    GENRE_ELECTRONICA,

    GENRE_CLASSICROCK,

    GENRE_INDIE,

    GENRE_METAL };

int genres;

int val = 0;

int prevVal = 0;

Process radio_process;

String label;

void setup() {

  genres = sizeof(stations)/sizeof(int);

  Bridge.begin();

  Serial.begin(9600);

  while(!Serial);  // wait for Serial port to connect.

  Serial.println("Grooveshark Radio example");

  start_radio(val);  

}

void loop() {

  val = analogRead(3);

  val = (val*genres)/1023;

  

  if(val != prevVal) {

    String text;

    text = "Value: ";

    text += val;

    Serial.println(text);

    start_radio(val);

    

    prevVal = val;

  }

// removed old code to print the output of the script: 

/*

  while(radio_process.available() > 0){

    char c = radio_process.read();

    Serial.print(c);

  }

*/

  char labelbuffer[256];

  Bridge.get("songName", labelbuffer, 256); 

  if (String(labelbuffer).length() > 0 && label != String(labelbuffer)){

    label = String(labelbuffer);

    

    Serial.println(label);

  }

  

  

  delay(400);

}

void start_radio(int val) {

    String parameter = "";

    radio_process.close();

    Process killer;

    killer.begin("killall");

    killer.addParameter("mpg123");

    killer.run();

    if(stations[val] != 0) {

      radio_process.begin("python");

      radio_process.addParameter("/root/examples-pygrooveshark/radio_mpg123.py");

      parameter+= stations[val];

      radio_process.addParameter(parameter);

      radio_process.runAsynchronously();

    }

    else {

      radio_process.begin("echo");

      radio_process.addParameter("Do Nothing!!!");

      radio_process.runAsynchronously();

    }

}