tripal/tripal_ws/tripal_ws.module

<?php


/**
 * Implements hook_init()
 */
function tripal_ws_init() {
  global $base_url;

  $version = 'v0.1';
  $api_url = $base_url . '/ws/' . $version;

  // Following the WC3 Hydra documentation, we want to add  LINK to the header
  // of the site that indicates where the API documentation can be found.
  // This allows a hydra-enabled client to discover the API and use it.
  $attributes = array(
    'rel' => 'http://www.w3.org/ns/hydra/core#apiDocumentation',
    'href' => $api_url . '/ws-doc/',
  );
  drupal_add_html_head_link($attributes, $header = FALSE);
}

/**
 * Implements hook_menu().
 * Defines all menu items needed by Tripal Core
 *
 * @ingroup tripal_ws
 */
function tripal_ws_menu() {

  // Web Services API callbacks.
  $items['ws'] = array(
    'title' => 'Tripal Web Services API',
    'page callback' => 'tripal_ws_services',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
  );

  // Tripal Web Services setting groups
  $items['admin/tripal/ws'] = array(
    'title' => 'Web Services',
    'description' => t("Exchange data between Tripal sites using the web services."),
    'weight' => 20,
    'page callback' => 'system_admin_menu_block_page',
    'access arguments' => array('administer tripal'),
    'file' => 'system.admin.inc',
    'file path' => drupal_get_path('module', 'system'),
  );
  $items['admin/tripal/ws/tripal_sites'] = array(
    'title' => 'Other Tripal Sites',
    'description' => t('Provides information about other Tripal sites.
        This allows data exchange and communication betwen Tripal
        enabled sites through the web services.'),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('tripal_ws_tripal_sites_form'),
    'access arguments' => array('administer tripal'),
    'type' => MENU_NORMAL_ITEM,
    'weight' => 0,
    'file' => 'includes/tripal_ws.admin.inc',
    'file path' => drupal_get_path('module', 'tripal_ws'),
  );
  return $items;
}

/**
 * The callback function for all RESTful web services.
 *
 */
function tripal_ws_services() {
  $ws_path = func_get_args();
  $params = $_GET;
  unset($params['q']);

  // The web services should never be cached.
  drupal_page_is_cacheable(FALSE);

  // Using the provided version number, determine which web services
  // verion to call.
  $version = array_shift($ws_path);
  if ($version and preg_match('/v\d+\.\d+/', $version)) {

    $api_url = 'ws/' . $version;

    // Add the file with the appropriate web services.
    module_load_include('inc', 'tripal_ws', 'includes/tripal_ws.rest_' . $version);
    $version = preg_replace('/\./', '_', $version);
    $function = 'tripal_ws_services_' . $version;
    $response = array();
    if (function_exists($function)) {
      $response = $function($api_url, $ws_path, $params);
    }
  }
  else {
    // TODO: What do we do if no version is provided?
  }

  drupal_add_http_header('Content-Type', 'application/ld+json');
  print drupal_json_encode($response);
}