Example API for redirecting CasperJS to Drupal data.

example_api.module

<?php

/**
 * Implements hook_menu().
 */
function example_api_menu() {
  $items = array();
  $items['api'] = array(
    'page callback' => 'example_api_redirect',
    'page arguments' => array(1, 2),
    'access callback' => TRUE,
  );
  return $items;
}

/**
 * Page callback for api/%s/%s.
 *
 * Redirect users from e.g. api/publications/12405 to node/2351.
 */
function example_api_redirect($type, $id) {
  // Check if $type is allowed.
  $allowed_types = array(
    'publication',
    'journal',
    // etc etc
  );
  if (!in_array(check_plain($type), $allowed_types)) {
    drupal_access_denied();
  }
  $id = check_plain($id);
  _example_api_get_content_by_source_id($type, $id);
}

/**
 * Redirects visitor to Drupal entity that matches source content type and ID.
 */
function _example_api_get_content_by_source_id($type, $id) {
  $drupal_id = NULL;
  $query = new EntityFieldQuery();
  $admin_user = user_load(1);
  $entity_type = 'node';
  switch ($type) {
    case 'publication':
      $query->entityCondition('entity_type', 'node')
        ->entityCondition('bundle', 'publication')
        ->fieldCondition('field_publication_id', 'value', $id)
        ->addMetaData('account', $admin_user);
      break;

    case 'journal':
      $entity_type = 'journal';
      $query->entityCondition('entity_type', 'journal')
        ->entityCondition('bundle', 'journal')
        ->fieldCondition('field_journal_id', 'value', $id)
        ->addMetaData('account', $admin_user);
      break;

    // Etc etc.
  }

  $result = $query->execute();
  if (isset($result[$entity_type])) {
    // Check if there is more than one result.
    $count = count($result[$entity_type]);
    // Get the first item in the results.
    $entity = array_shift($result[$entity_type]);
    if ($count > 1) {
      // Build a list of IDs of duplicate entities.
      if ($entity_type == 'entity') {
        $ids = implode(', ', array_keys($result[$entity_type]));
      }
      else {
        $ids = array();
        foreach ($result[$entity_type] as $item) {
          $ids[] = $item->nid;
        }
        $ids = implode(', ', $ids);
      }
      drupal_set_message(t('We found more than one entity matching id %id. Other entity IDs found are %entities',
        array(
          '%id' => $id,
          '%entities' => $ids,
        )
      ),
      'warning');
    }
    $drupal_id = ($entity_type == 'node') ? $entity->nid : $entity->id;
  }

  $success_message = t('Successfully located Drupal entity for type %type and id %id', array('%type' => $type, '%id' => $id));
  if (!$drupal_id) {
    drupal_set_message(t('Could not find a Drupal entity for type %type and id %id', array('%type' => $type, '%id' => $id)), 'warning');
    drupal_not_found();
  }
  elseif ($entity_type == 'node') {
    drupal_set_message($success_message, 'success');
    drupal_goto('node/' . $drupal_id);
  }
  else {
    drupal_set_message($success_message, 'success');
    drupal_goto($entity_type . '/' . $entity_type . '/' . $drupal_id);
  }
}