Determines if the current page call is via Services. (Drupal 6)

gistfile1.php

<?php

/**
 * Determines if the current page call is via Services.
 *
 * @return bool
 *   TRUE if request is via Services, FALSE otherwise.
 */
function _determine_if_call_via_services() {
  $args = arg();
  $services_endpoints = array_flip(array_keys(services_endpoint_load_all()));
  if (array_key_exists($args[0], $services_endpoints)) {
    $service_resources_raw = services_get_resources($args[0]);
    $service_resources = array_flip(array_keys($service_resources_raw));
    return in_array($args[1], $service_resources);
  }
  else {
    return FALSE;
  }
}