contract EventPublisher {
  /*
   * event declaration: declare event topics
   * equivalent to
   * event AT_LEAST_ONCE te;
   * can be used by function te and tes
   * function te: publish an event with topic 'te' and default semantics AT_LEAST_ONCE
   * function tes: publish an event with topic 'te' and another semantics
   */
  event global te;
  /*
   * event declaration with semantics
   * valid semantics: AT_LEASE_ONCE, AT_MOST_ONCE, and ONLY_ONCE
   * can be used by function tews and tewss
   * function tews: publish an event with topic 'tews' and semantics AT_MOST_ONCE
   * function tewss: publish an event with topic 'tews' and another semantics
   */
  event global tews(AT_MOST_ONCE);
  // publish an event with declared topic and default semantics AT_LEAST_ONCE
  export function pub1(e) {
    var content = YancloudUtil.random() + ' EventPublisher.pub1';
    // equivalent to
    // tes(content, 'AT_LEAST_ONCE')
    te(content);
    return 'done';
  }
  // publish an event with declared topic and semantics
  export function pub2(e) {
    var content = YancloudUtil.random() + ' EventPublisher.pub2';
    // equivalent to
    // tewss(content, 'AT_MOST_ONCE')
    tews(content);
    return 'done';
  }
  // YancloudUtil.pubEvent and YancloudUtil.pubEventConstraint are used to publish events without event declarations
  export function pub3(constraint) {
    var content = YancloudUtil.random() + ' EventPublisher.pub3';
    if (!constraint) {
      /*
       * YancloudUtil.pubEvent is used to publish events with a some topic and default semantics AT_LEAST_ONCE
       * equivalent to
       * YancloudUtil.pubEventConstraint('topic', content, 'AT_LEAST_ONCE');
       */
      YancloudUtil.pubEvent('topic', content);
    }
    else {
      // YancloudUtil.pubEventConstraint is used to publish events with a topic and another semantics
      YancloudUtil.pubEventConstraint('topic', content, constraint);
    }
    return 'done';
  }
}