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Differences Between: [Versions 310 and 401] [Versions 311 and 401] [Versions 39 and 401] [Versions 400 and 401]

   1  <?php
   2  
   3  // This file is part of Moodle - http://moodle.org/
   4  //
   5  // Moodle is free software: you can redistribute it and/or modify
   6  // it under the terms of the GNU General Public License as published by
   7  // the Free Software Foundation, either version 3 of the License, or
   8  // (at your option) any later version.
   9  //
  10  // Moodle is distributed in the hope that it will be useful,
  11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  // GNU General Public License for more details.
  14  //
  15  // You should have received a copy of the GNU General Public License
  16  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17  
  18  /**
  19   * Provides various useful functionality to plugins that offer or use this MNet service
  20   *
  21   * Remote enrolment service is used by enrol_mnet plugin which publishes the server side
  22   * methods. The client side is accessible from the admin tree.
  23   *
  24   * @package    mnetservice
  25   * @subpackage enrol
  26   * @copyright  2010 David Mudrak <david@moodle.com>
  27   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  28   */
  29  
  30  defined('MOODLE_INTERNAL') || die();
  31  
  32  require_once($CFG->dirroot . '/user/selector/lib.php');
  33  
  34  /**
  35   * Singleton providing various functionality usable by plugin(s) implementing this MNet service
  36   */
  37  class mnetservice_enrol {
  38  
  39      /** @var mnetservice_enrol holds the singleton instance. */
  40      protected static $singleton;
  41  
  42      /** @var caches the result of {@link self::get_remote_subscribers()} */
  43      protected $cachesubscribers = null;
  44  
  45      /** @var caches the result of {@link self::get_remote_publishers()} */
  46      protected $cachepublishers = null;
  47  
  48      /**
  49       * This is singleton, use {@link mnetservice_enrol::get_instance()}
  50       */
  51      protected function __construct() {
  52      }
  53  
  54      /**
  55       * @return mnetservice_enrol singleton instance
  56       */
  57      public static function get_instance() {
  58          if (is_null(self::$singleton)) {
  59              self::$singleton = new self();
  60          }
  61          return self::$singleton;
  62      }
  63  
  64      /**
  65       * Is this service enabled?
  66       *
  67       * Currently, this checks if whole MNet is available. In the future, additional
  68       * checks can be done. Probably the field 'offer' should be checked but it does
  69       * not seem to be used so far.
  70       *
  71       * @todo move this to some parent class once we have such
  72       * @return bool
  73       */
  74      public function is_available() {
  75          global $CFG;
  76  
  77          if (empty($CFG->mnet_dispatcher_mode) || $CFG->mnet_dispatcher_mode !== 'strict') {
  78              return false;
  79          }
  80          return true;
  81      }
  82  
  83      /**
  84       * Returns a list of remote servers that can enrol their users into our courses
  85       *
  86       * We must publish MNet service 'mnet_enrol' for the peers to allow them to enrol
  87       * their users into our courses.
  88       *
  89       * @todo once the MNet core is refactored this may be part of a parent class
  90       * @todo the name of the service should be changed to the name of this plugin
  91       * @return array
  92       */
  93      public function get_remote_subscribers() {
  94          global $DB;
  95  
  96          if (is_null($this->cachesubscribers)) {
  97              $sql = "SELECT DISTINCT h.id, h.name AS hostname, h.wwwroot AS hosturl,
  98                             a.display_name AS appname
  99                        FROM {mnet_host} h
 100                        JOIN {mnet_host2service} hs ON h.id = hs.hostid
 101                        JOIN {mnet_service} s ON hs.serviceid = s.id
 102                        JOIN {mnet_application} a ON h.applicationid = a.id
 103                       WHERE s.name = 'mnet_enrol'
 104                             AND h.deleted = 0
 105                             AND hs.publish = 1";
 106              $this->cachesubscribers = $DB->get_records_sql($sql);
 107          }
 108  
 109          return $this->cachesubscribers;
 110      }
 111  
 112      /**
 113       * Returns a list of remote servers that offer their courses for our users
 114       *
 115       * We must subscribe MNet service 'mnet_enrol' for the peers to allow our users to enrol
 116       * into their courses.
 117       *
 118       * @todo once the MNet core is refactored this may be part of a parent class
 119       * @todo the name of the service should be changed to the name of this plugin
 120       * @return array
 121       */
 122      public function get_remote_publishers() {
 123          global $DB;
 124  
 125          if (is_null($this->cachepublishers)) {
 126              $sql = "SELECT DISTINCT h.id, h.name AS hostname, h.wwwroot AS hosturl,
 127                             a.display_name AS appname
 128                        FROM {mnet_host} h
 129                        JOIN {mnet_host2service} hs ON h.id = hs.hostid
 130                        JOIN {mnet_service} s ON hs.serviceid = s.id
 131                        JOIN {mnet_application} a ON h.applicationid = a.id
 132                       WHERE s.name = 'mnet_enrol'
 133                             AND h.deleted = 0
 134                             AND hs.subscribe = 1";
 135              $this->cachepublishers = $DB->get_records_sql($sql);
 136          }
 137  
 138          return $this->cachepublishers;
 139      }
 140  
 141      /**
 142       * Fetches the information about the courses available on remote host for our students
 143       *
 144       * The information about remote courses available for us is cached in {mnetservice_enrol_courses}.
 145       * This method either returns the cached information (typically when displaying the list to
 146       * students) or fetch fresh data via new XML-RPC request (which updates the local cache, too).
 147       * The lifetime of the cache is 1 day, so even if $usecache is set to true, the cache will be
 148       * re-populated if we did not fetch from any server (not only the currently requested one)
 149       * for some time.
 150       *
 151       * @param id $mnethostid MNet remote host id
 152       * @param bool $usecache use cached data or invoke new XML-RPC?
 153       * @uses mnet_xmlrpc_client Invokes XML-RPC request if the cache is not used
 154       * @return array|string returned list or serialized array of mnet error messages
 155       */
 156      public function get_remote_courses($mnethostid, $usecache=true) {
 157          global $CFG, $DB; // $CFG needed!
 158  
 159          $lastfetchcourses = get_config('mnetservice_enrol', 'lastfetchcourses');
 160          if (empty($lastfetchcourses) or (time()-$lastfetchcourses > DAYSECS)) {
 161              $usecache = false;
 162          }
 163  
 164          if ($usecache) {
 165              return $DB->get_records('mnetservice_enrol_courses', array('hostid' => $mnethostid), 'sortorder, shortname');
 166          }
 167  
 168          // do not use cache - fetch fresh list from remote MNet host
 169          require_once $CFG->dirroot.'/mnet/xmlrpc/client.php';
 170          $peer = new mnet_peer();
 171          if (!$peer->set_id($mnethostid)) {
 172              return serialize(array('unknown mnet peer'));
 173          }
 174  
 175          $request = new mnet_xmlrpc_client();
 176          $request->set_method('enrol/mnet/enrol.php/available_courses');
 177  
 178          if ($request->send($peer)) {
 179              $list = array();
 180              $response = $request->response;
 181  
 182              // get the currently cached courses key'd on remote id - only need remoteid and id fields
 183              $cachedcourses = $DB->get_records('mnetservice_enrol_courses', array('hostid' => $mnethostid), 'remoteid', 'remoteid, id');
 184  
 185              foreach ($response as &$remote) {
 186                  $course                 = new stdclass(); // record in our local cache
 187                  $course->hostid         = $mnethostid;
 188                  $course->remoteid       = (int)$remote['remoteid'];
 189                  $course->categoryid     = (int)$remote['cat_id'];
 190                  $course->categoryname   = substr($remote['cat_name'], 0, 255);
 191                  $course->sortorder      = (int)$remote['sortorder'];
 192                  $course->fullname       = substr($remote['fullname'], 0, 254);
 193                  $course->shortname      = substr($remote['shortname'], 0, 100);
 194                  $course->idnumber       = substr($remote['idnumber'], 0, 100);
 195                  $course->summary        = $remote['summary'];
 196                  $course->summaryformat  = empty($remote['summaryformat']) ? FORMAT_MOODLE : (int)$remote['summaryformat'];
 197                  $course->startdate      = (int)$remote['startdate'];
 198                  $course->roleid         = (int)$remote['defaultroleid'];
 199                  $course->rolename       = substr($remote['defaultrolename'], 0, 255);
 200                  // We do not cache the following fields returned from peer in 2.0 any more
 201                  // not cached: cat_description
 202                  // not cached: cat_descriptionformat
 203                  // not cached: cost
 204                  // not cached: currency
 205  
 206                  if (empty($cachedcourses[$course->remoteid])) {
 207                      $course->id = $DB->insert_record('mnetservice_enrol_courses', $course);
 208                  } else {
 209                      $course->id = $cachedcourses[$course->remoteid]->id;
 210                      $DB->update_record('mnetservice_enrol_courses', $course);
 211                  }
 212  
 213                  $list[$course->remoteid] = $course;
 214              }
 215  
 216              // prune stale data from cache
 217              if (!empty($cachedcourses)) {
 218                  foreach ($cachedcourses as $cachedcourse) {
 219                      if (!empty($list[$cachedcourse->remoteid])) {
 220                          unset($cachedcourses[$cachedcourse->remoteid]);
 221                      }
 222                  }
 223                  $staleremoteids = array_keys($cachedcourses);
 224                  if (!empty($staleremoteids)) {
 225                      list($sql, $params) = $DB->get_in_or_equal($staleremoteids, SQL_PARAMS_NAMED);
 226                      $select = "hostid=:hostid AND remoteid $sql";
 227                      $params['hostid'] = $mnethostid;
 228                      $DB->delete_records_select('mnetservice_enrol_courses', $select, $params);
 229                  }
 230              }
 231  
 232              // and return the fresh data
 233              set_config('lastfetchcourses', time(), 'mnetservice_enrol');
 234              return $list;
 235  
 236          } else {
 237              return serialize($request->error);
 238          }
 239      }
 240  
 241      /**
 242       * Updates local cache about enrolments of our users in remote courses
 243       *
 244       * The remote course must allow enrolments via our Remote enrolment service client.
 245       * Because of legacy design of data structure returned by XML-RPC code, only one
 246       * user enrolment per course is returned by 1.9 MNet servers. This may be an issue
 247       * if the user is enrolled multiple times by various enrolment plugins. MNet 2.0
 248       * servers do not use user name as array keys - they do not need to due to side
 249       * effect of MDL-19219.
 250       *
 251       * @param id $mnethostid MNet remote host id
 252       * @param int $remotecourseid ID of the course at the remote host
 253       * @param bool $usecache use cached data or invoke new XML-RPC?
 254       * @uses mnet_xmlrpc_client Invokes XML-RPC request
 255       * @return bool|string true if success or serialized array of mnet error messages
 256       */
 257      public function req_course_enrolments($mnethostid, $remotecourseid) {
 258          global $CFG, $DB; // $CFG needed!
 259          require_once $CFG->dirroot.'/mnet/xmlrpc/client.php';
 260  
 261          if (!$DB->record_exists('mnetservice_enrol_courses', array('hostid'=>$mnethostid, 'remoteid'=>$remotecourseid))) {
 262              return serialize(array('course not available for remote enrolments'));
 263          }
 264  
 265          $peer = new mnet_peer();
 266          if (!$peer->set_id($mnethostid)) {
 267              return serialize(array('unknown mnet peer'));
 268          }
 269  
 270          $request = new mnet_xmlrpc_client();
 271          $request->set_method('enrol/mnet/enrol.php/course_enrolments');
 272          $request->add_param($remotecourseid, 'int');
 273  
 274          if ($request->send($peer)) {
 275              $list = array();
 276              $response = $request->response;
 277  
 278              // prepare a table mapping usernames of our users to their ids
 279              $usernames = array();
 280              foreach ($response as $unused => $remote) {
 281                  if (!isset($remote['username'])) {
 282                      // see MDL-19219
 283                      return serialize(array('remote host running old version of mnet server - does not return username attribute'));
 284                  }
 285                  if ($remote['username'] == 'guest') { // we can not use $CFG->siteguest here
 286                      // do not try nasty things you bastard!
 287                      continue;
 288                  }
 289                  $usernames[$remote['username']] = $remote['username'];
 290              }
 291  
 292              if (!empty($usernames)) {
 293                  list($usql, $params) = $DB->get_in_or_equal($usernames, SQL_PARAMS_NAMED);
 294                  list($sort, $sortparams) = users_order_by_sql();
 295                  $params['mnetlocalhostid'] = $CFG->mnet_localhost_id;
 296                  $sql = "SELECT username,id
 297                            FROM {user}
 298                           WHERE mnethostid = :mnetlocalhostid
 299                                 AND username $usql
 300                                 AND deleted = 0
 301                                 AND confirmed = 1
 302                        ORDER BY $sort";
 303                  $usersbyusername = $DB->get_records_sql($sql, array_merge($params, $sortparams));
 304              } else {
 305                  $usersbyusername = array();
 306              }
 307  
 308              // populate the returned list and update local cache of enrolment records
 309              foreach ($response as $remote) {
 310                  if (empty($usersbyusername[$remote['username']])) {
 311                      // we do not know this user or she is deleted or not confirmed or is 'guest'
 312                      continue;
 313                  }
 314                  $enrolment                  = new stdclass();
 315                  $enrolment->hostid          = $mnethostid;
 316                  $enrolment->userid          = $usersbyusername[$remote['username']]->id;
 317                  $enrolment->remotecourseid  = $remotecourseid;
 318                  $enrolment->rolename        = $remote['name']; // $remote['shortname'] not used
 319                  $enrolment->enroltime       = $remote['timemodified'];
 320                  $enrolment->enroltype       = $remote['enrol'];
 321  
 322                  $current = $DB->get_record('mnetservice_enrol_enrolments', array('hostid'=>$enrolment->hostid, 'userid'=>$enrolment->userid,
 323                                         'remotecourseid'=>$enrolment->remotecourseid, 'enroltype'=>$enrolment->enroltype), 'id, enroltime');
 324                  if (empty($current)) {
 325                      $enrolment->id = $DB->insert_record('mnetservice_enrol_enrolments', $enrolment);
 326                  } else {
 327                      $enrolment->id = $current->id;
 328                      if ($current->enroltime != $enrolment->enroltime) {
 329                          $DB->update_record('mnetservice_enrol_enrolments', $enrolment);
 330                      }
 331                  }
 332  
 333                  $list[$enrolment->id] = $enrolment;
 334              }
 335  
 336              // prune stale enrolment records
 337              if (empty($list)) {
 338                  $DB->delete_records('mnetservice_enrol_enrolments', array('hostid'=>$mnethostid, 'remotecourseid'=>$remotecourseid));
 339              } else {
 340                  list($isql, $params) = $DB->get_in_or_equal(array_keys($list), SQL_PARAMS_NAMED, 'param', false);
 341                  $params['hostid'] = $mnethostid;
 342                  $params['remotecourseid'] = $remotecourseid;
 343                  $select = "hostid = :hostid AND remotecourseid = :remotecourseid AND id $isql";
 344                  $DB->delete_records_select('mnetservice_enrol_enrolments', $select, $params);
 345              }
 346  
 347              // store the timestamp of the recent fetch, can be used for cache invalidate purposes
 348              set_config('lastfetchenrolments', time(), 'mnetservice_enrol');
 349              // local cache successfully updated
 350              return true;
 351  
 352          } else {
 353              return serialize($request->error);
 354          }
 355      }
 356  
 357      /**
 358       * Send request to enrol our user to the remote course
 359       *
 360       * Updates our remote enrolments cache if the enrolment was successful.
 361       *
 362       * @uses mnet_xmlrpc_client Invokes XML-RPC request
 363       * @param object $user our user
 364       * @param object $remotecourse record from mnetservice_enrol_courses table
 365       * @return true|string true if success, error message from the remote host otherwise
 366       */
 367      public function req_enrol_user(stdclass $user, stdclass $remotecourse) {
 368          global $CFG, $DB;
 369          require_once($CFG->dirroot.'/mnet/xmlrpc/client.php');
 370  
 371          $peer = new mnet_peer();
 372          $peer->set_id($remotecourse->hostid);
 373  
 374          $request = new mnet_xmlrpc_client();
 375          $request->set_method('enrol/mnet/enrol.php/enrol_user');
 376          $request->add_param(mnet_strip_user((array)$user, mnet_fields_to_send($peer)));
 377          $request->add_param($remotecourse->remoteid);
 378  
 379          if ($request->send($peer) === true) {
 380              if ($request->response === true) {
 381                  // cache the enrolment information in our table
 382                  $enrolment                  = new stdclass();
 383                  $enrolment->hostid          = $peer->id;
 384                  $enrolment->userid          = $user->id;
 385                  $enrolment->remotecourseid  = $remotecourse->remoteid;
 386                  $enrolment->enroltype       = 'mnet';
 387                  // $enrolment->rolename not known now, must be re-fetched
 388                  // $enrolment->enroltime not known now, must be re-fetched
 389                  $DB->insert_record('mnetservice_enrol_enrolments', $enrolment);
 390                  return true;
 391  
 392              } else {
 393                  return serialize(array('invalid response: '.print_r($request->response, true)));
 394              }
 395  
 396          } else {
 397              return serialize($request->error);
 398          }
 399      }
 400  
 401      /**
 402       * Send request to unenrol our user from the remote course
 403       *
 404       * Updates our remote enrolments cache if the unenrolment was successful.
 405       *
 406       * @uses mnet_xmlrpc_client Invokes XML-RPC request
 407       * @param object $user our user
 408       * @param object $remotecourse record from mnetservice_enrol_courses table
 409       * @return true|string true if success, error message from the remote host otherwise
 410       */
 411      public function req_unenrol_user(stdclass $user, stdclass $remotecourse) {
 412          global $CFG, $DB;
 413          require_once($CFG->dirroot.'/mnet/xmlrpc/client.php');
 414  
 415          $peer = new mnet_peer();
 416          $peer->set_id($remotecourse->hostid);
 417  
 418          $request = new mnet_xmlrpc_client();
 419          $request->set_method('enrol/mnet/enrol.php/unenrol_user');
 420          $request->add_param($user->username);
 421          $request->add_param($remotecourse->remoteid);
 422  
 423          if ($request->send($peer) === true) {
 424              if ($request->response === true) {
 425                  // clear the cached information
 426                  $DB->delete_records('mnetservice_enrol_enrolments',
 427                      array('hostid'=>$peer->id, 'userid'=>$user->id, 'remotecourseid'=>$remotecourse->remoteid, 'enroltype'=>'mnet'));
 428                  return true;
 429  
 430              } else {
 431                  return serialize(array('invalid response: '.print_r($request->response, true)));
 432              }
 433  
 434          } else {
 435              return serialize($request->error);
 436          }
 437      }
 438  
 439      /**
 440       * Prepares error messages returned by our XML-RPC requests to be send as debug info to {@see \moodle_exception()}
 441       *
 442       * MNet client-side methods in this class return request error as serialized array.
 443       *
 444       * @param string $error serialized array
 445       * @return string
 446       */
 447      public function format_error_message($errormsg) {
 448          $errors = unserialize($errormsg);
 449          $output = 'mnet_xmlrpc_client request returned errors:'."\n";
 450          foreach ($errors as $error) {
 451              $output .= "$error\n";
 452          }
 453          return $output;
 454      }
 455  }
 456  
 457  /**
 458   * Selector of our users enrolled into remote course via enrol_mnet plugin
 459   */
 460  class mnetservice_enrol_existing_users_selector extends user_selector_base {
 461      /** @var id of the MNet peer */
 462      protected $hostid;
 463      /** @var id of the course at the remote server */
 464      protected $remotecourseid;
 465  
 466      public function __construct($name, $options) {
 467          $this->hostid = $options['hostid'];
 468          $this->remotecourseid = $options['remotecourseid'];
 469          parent::__construct($name, $options);
 470      }
 471  
 472      /**
 473       * Find our users currently enrolled into the remote course
 474       *
 475       * @param string $search
 476       * @return array
 477       */
 478      public function find_users($search) {
 479          global $DB;
 480  
 481          list($wherecondition, $params)  = $this->search_sql($search, 'u');
 482          $params['hostid']               = $this->hostid;
 483          $params['remotecourseid']       = $this->remotecourseid;
 484  
 485          $fields      = "SELECT ".$this->required_fields_sql("u");
 486          $countfields = "SELECT COUNT(1)";
 487  
 488          $sql = "          FROM {user} u
 489                            JOIN {mnetservice_enrol_enrolments} e ON e.userid = u.id
 490                           WHERE e.hostid = :hostid AND e.remotecourseid = :remotecourseid
 491                                 AND e.enroltype = 'mnet'
 492                                 AND $wherecondition";
 493  
 494          list($sort, $sortparams) = users_order_by_sql('u');
 495          $order = "    ORDER BY $sort";
 496  
 497          if (!$this->is_validating()) {
 498              $potentialmemberscount = $DB->count_records_sql($countfields . $sql, $params);
 499              if ($potentialmemberscount > 100) {
 500                  return $this->too_many_results($search, $potentialmemberscount);
 501              }
 502          }
 503  
 504          $availableusers = $DB->get_records_sql($fields . $sql . $order, array_merge($params, $sortparams));
 505  
 506          if (empty($availableusers)) {
 507              return array();
 508          }
 509  
 510          if ($search) {
 511              $groupname = get_string('enrolledusersmatching', 'enrol', $search);
 512          } else {
 513              $groupname = get_string('enrolledusers', 'enrol');
 514          }
 515  
 516          return array($groupname => $availableusers);
 517      }
 518  
 519      protected function get_options() {
 520          $options = parent::get_options();
 521          $options['hostid'] = $this->hostid;
 522          $options['remotecourseid'] = $this->remotecourseid;
 523          $options['file'] = 'mnet/service/enrol/locallib.php';
 524          return $options;
 525      }
 526  }
 527  
 528  /**
 529   * Selector of our users who could be enrolled into a remote course via their enrol_mnet
 530   */
 531  class mnetservice_enrol_potential_users_selector extends user_selector_base {
 532      /** @var id of the MNet peer */
 533      protected $hostid;
 534      /** @var id of the course at the remote server */
 535      protected $remotecourseid;
 536  
 537      public function __construct($name, $options) {
 538          $this->hostid = $options['hostid'];
 539          $this->remotecourseid = $options['remotecourseid'];
 540          parent::__construct($name, $options);
 541      }
 542  
 543      /**
 544       * Find our users who could be enrolled into the remote course
 545       *
 546       * Our users must have 'moodle/site:mnetlogintoremote' capability assigned.
 547       * Remote users, guests, deleted and not confirmed users are not returned.
 548       *
 549       * @param string $search
 550       * @return array
 551       */
 552      public function find_users($search) {
 553          global $CFG, $DB;
 554  
 555          $systemcontext = context_system::instance();
 556          $userids = get_users_by_capability($systemcontext, 'moodle/site:mnetlogintoremote', 'u.id');
 557  
 558          if (empty($userids)) {
 559              return array();
 560          }
 561  
 562          list($usql, $uparams) = $DB->get_in_or_equal(array_keys($userids), SQL_PARAMS_NAMED, 'uid');
 563  
 564          list($wherecondition, $params) = $this->search_sql($search, 'u');
 565  
 566          $params = array_merge($params, $uparams);
 567          $params['hostid'] = $this->hostid;
 568          $params['remotecourseid'] = $this->remotecourseid;
 569          $params['mnetlocalhostid'] = $CFG->mnet_localhost_id;
 570  
 571          $fields      = "SELECT ".$this->required_fields_sql("u");
 572          $countfields = "SELECT COUNT(1)";
 573  
 574          $sql = "          FROM {user} u
 575                           WHERE $wherecondition
 576                                 AND u.mnethostid = :mnetlocalhostid
 577                                 AND u.id $usql
 578                                 AND u.id NOT IN (SELECT e.userid
 579                                                    FROM {mnetservice_enrol_enrolments} e
 580                                                   WHERE (e.hostid = :hostid AND e.remotecourseid = :remotecourseid))";
 581  
 582          list($sort, $sortparams) = users_order_by_sql('u');
 583          $order = "    ORDER BY $sort";
 584  
 585          if (!$this->is_validating()) {
 586              $potentialmemberscount = $DB->count_records_sql($countfields . $sql, $params);
 587              if ($potentialmemberscount > 100) {
 588                  return $this->too_many_results($search, $potentialmemberscount);
 589              }
 590          }
 591  
 592          $availableusers = $DB->get_records_sql($fields . $sql . $order, array_merge($params, $sortparams));
 593  
 594          if (empty($availableusers)) {
 595              return array();
 596          }
 597  
 598          if ($search) {
 599              $groupname = get_string('enrolcandidatesmatching', 'enrol', $search);
 600          } else {
 601              $groupname = get_string('enrolcandidates', 'enrol');
 602          }
 603  
 604          return array($groupname => $availableusers);
 605      }
 606  
 607      protected function get_options() {
 608          $options = parent::get_options();
 609          $options['hostid'] = $this->hostid;
 610          $options['remotecourseid'] = $this->remotecourseid;
 611          $options['file'] = 'mnet/service/enrol/locallib.php';
 612          return $options;
 613      }
 614  }