How to get live data from a service?
Thanks for the advice. The solution:

For example, to get a three-hourly five-day forecast for Dunkeswell Aerodrome:

  $base = 'http://datapoint.metoffice.gov.uk/public/data/';
  $resource = 'val/wxfcs/all/json/3840?res=3hourly';
  $api_key = '&amp;key=abcde12345abcde12345';
  $url = $base . $resource . $api_key;
  $response = drupal_http_request($url);
  $data = json_decode($response-&gt;data, TRUE);