A basic definition of schedule would be as shown here:

<p:schedule id="lazySchedule"
  value="#{scheduleBean.lazyScheduleModel}"/>

The visual output of the component with two randomly generated events will be as shown here:

By default, the month view is displayed, so the user sees a whole month and can switch between months. Assume that we have to load events for 12 months and every month requires, on average, 1.5 seconds for event loading. The default eager mode would take 18 seconds (12 x 1.5) to load all events. This is too long, so using the lazy loading feature is recommended to improve performance. The ScheduleBean bean definition with lazy model construction is given next; for the sake of simplicity, the loading time is simulated with Thread.sleep(1500):

@Named
@ViewScoped
public class ScheduleBean implements Serializable {

  private ScheduleModel lazyEventModel;

  @PostConstruct
  public void initialize() {
    lazyEventModel = new LazyScheduleModel() {

      @Override
      public void loadEvents(Date start, Date end) {
        try {
          // simulate a long running task
          Thread.sleep(1500);
        } catch (Exception e) {
      }

      clear();

      Date random = getRandomDate(start);
      addEvent(new DefaultScheduleEvent("Lazy Event 1",
        random, random));

      random = getRandomDate(start);
      addEvent(new DefaultScheduleEvent("Lazy Event 2",
        random, random));
      }
    };
  }

  public Date getRandomDate(Date base) {
    Calendar date = Calendar.getInstance();
    date.setTime(base);
    date.add(Calendar.DATE, ((int) (Math.random() * 30)) + 1);

   return date.getTime();
  }

  public ScheduleModel getLazyScheduleModel() {
    return lazyEventModel;
  }
}

To enable lazy loading of the schedule component's events, we need to provide an instance of org.primefaces.model.LazyScheduleModel and implement the loadEvents method. This method is called with new date boundaries every time the displayed timeframe is changed. Events are now loaded on demand on the initial page load or during switching between months. That means the maximum delay for the event's loading is not longer than 1.5 seconds.

The Schedule component offers five different views, which are month, agendaWeek, agendaDay, basicWeek, and basicDay. The default view is month, and the rest of the modes are given here with their visual outputs:

Agenda week view

Agenda day view

Basic week view

Basic day view

<p:ajax event="dateSelect" listener="#{scheduleBean.onDateSelect}"
  update=":mainForm:growl" />
<p:ajax event="eventSelect" update=":mainForm:growl"
  listener="#{scheduleBean.onEventSelect}"/>
<p:ajax event="eventMove" listener="#{scheduleBean.onEventMove}" 
  update=":mainForm:growl" />
<p:ajax event="eventResize" update=":mainForm:growl"
  listener="#{scheduleBean.onEventResize}" />
<p:ajax event="viewChange" listener="#{scheduleBean.onViewChange}" 
  update=":mainForm:growl" />

public void onDateSelect(SelectEvent event) {
  MessageUtil.addInfoMessage("date.selected", event.getObject());
}

public void onEventSelect(SelectEvent event) {
  MessageUtil.addInfoMessage("event.selected",
    ((DefaultScheduleEvent)event.getObject()).getTitle());
}

public void onEventMove(ScheduleEntryMoveEvent event) {
  MessageUtil.addInfoMessage("event.moved", 
    event.getScheduleEvent().getTitle(), event.getDayDelta(),
    event.getMinuteDelta());
}

public void onEventResize(ScheduleEntryResizeEvent event) {
  MessageUtil.addInfoMessage("event.resized",
    event.getScheduleEvent().getTitle(), event.getDayDelta(),
    event. getMinuteDelta());
}

public void onViewChange(SelectEvent event) {
  MessageUtil.addInfoMessage("view.changed", event.getObject());
}

For details about the MessageUtil class, see the Internationalization (i18n) and Localization (L10n) recipe in Chapter 1, Getting Started with PrimeFaces.