load() {
  if (this.data) {
    // already loaded data
    return Promise.resolve(this.data);
  }

  // don't have the data yet
  return new Promise(resolve => {
      this.http.get('URL-TO-JSON').subscribe(res => {
          this.data = this.processData(res.json());
          resolve(this.data);
        });
  });
}

forceLoadNew() {
  return new Promise(resolve => {
      this.http.get('URL-TO-JSON').subscribe(res => {
          this.data = this.processData(res.json());
          resolve(this.data);
      });
  });
}

getSpeakers() {
  return this.forceLoadNew().then(data => {
    return data.speakers.sort((a, b) => {
      let aName = a.name.split(' ').pop();
      let bName = b.name.split(' ').pop();
      return aName.localeCompare(bName);
    });
  });
}

reloadUpdates(event) {
  this.confData.getSpeakers().then(speakers => {
    this.speakers = speakers;
  });
}