Feedprinter

From Hackypedia

Contents 1 Project Members 2 Idea 3 Blueprint 4 Implementation

[edit] Project Members

• Guy

[edit] Idea

Dot Matrix printer fed a continuous stream of paper, to print tweets which contain a search term in near realtime.

[edit] Blueprint

• Script that polls the Twitter API for tweets with a given keyword

Interval ?

Need to sanitise text ?

http://search.twitter.com/search.json?q=hacman&since_id=1520639490

• Parses returned JSON and populates message queue

 search(id,value);
 message_queue(message_id,search_id,time,from_user,from_user_id,to_user_id,message);
 last_message(search_id,message_id);

• Arduino calls a script that returns the next message

return ascii string containing CR and LF that can be streamed straight to the printer

[edit] Implementation

Test implementation of reading data from Twitter API and parsing it: http://www.thouret.co.uk/jsontest.php?q=stockport

MySQL database schema as in blueprint created.

Script now in place and run by cron every 5mins to populate the message_queue table:

  # Twitter Poller
  # Guy Thouret
  # 9/2/2010

  # get_url function	
    function get_url($url) { 
      $ch = curl_init();
      curl_setopt($ch,CURLOPT_URL,$url);
      curl_setopt($ch,CURLOPT_RETURNTRANSFER,
      curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,
      $content = curl_exec($ch);
      curl_close($ch);
      return $content;
    }
	
    # Script constants
    $debug		= false;
    $twitter_search_api	= "http://search.twitter.com/search.json";
    $dbhost		= 'localhost';
    $dbuser		= 'xxxx';
    $dbpass		= 'xxxx';
    $dbname		= 'feedprinter';

    # DB Connection
    $conn = mysql_connect($dbhost, $dbuser, $dbpass) or die('Error connecting to mysql');
    mysql_select_db($dbname);

    # Perform Searches
    $q = "SELECT * FROM search";
    $r = mysql_query($q);
    
    while ($row = mysql_fetch_assoc($r)) {
        # Get Last ID
        $q2 = "SELECT message_id FROM last_message WHERE search_id = ".$row['id'];
        $r2 = mysql_query($q2);
        $row2 =  mysql_fetch_assoc($r2);

        $last_id = $row2['message_id'];
        if ($debug) {
            echo "lastid=".$last_id;
        }
        print_r($row2);
        
        $json_result = get_url($twitter_search_api."?q=".$row['value']."&since_id=".$last_id);
        $result = json_decode($json_result);
        
        $last_id = 0;
        foreach ($result->results as $tweet) {
            $q3 = "INSERT INTO message_queue VALUES ('".$tweet->id."','".$row['id']."','".$tweet->created_at."','".$tweet->from_user."','".$tweet->from_user_id."','".$tweet->to_user_id."','".$tweet->text."')";
            $r3 = mysql_query($q3);
            if ($debug) {
                echo $q3;
            }
            if ($tweet->id > $last_id) $last_id = $tweet->id; 
        }

        if ($last_id != 0) {
            $q4 = "UPDATE last_message SET message_id=".$last_id." WHERE search_id=".$row['id'];
            $r4 = mysql_query($q4);
        }
    }

    mysql_close($conn)