Ajax Timelines and the Semantic Web
Timeline lets you view points and durations of time in an intuitive manner. I refer to these as time events or just events when the context is clear. Many bands at different granularities—hour, day, month, year and so on—can show you how events relate to each other. You can use the mouse to drag around the display, or double-click on the Timeline to center at that time. All events can have click bubbles showing a little HTML with links and images.
Using Timeline itself requires no software installation on the client or Web server. Although there are no requirements for installing Timeline, while developing Timeline Web sites, you can improve reload speed by installing Timeline on the local machine. To do this, check out a copy of Timeline from Subversion, and change the script path in your Timeline HTML files to point to your local copy.
Listing 1. Get Timeline from Subversion for quicker reloads.
$ svn checkout \ http://simile.mit.edu/repository/timeline/
Many day, week, month and year sliders can be created using the Timeline.createBandInfo(), which selects the time unit and screen size relative to the entire Timeline that each band will consume. The Timeline is populated with time event data from an XML file using Timeline.loadXML(). An update function also should be called in onResize() to allow the Timeline to redraw itself.
The XML file containing the dates is shown in Listing 3. This contains two types of durations: one we are sure of and one that is just a rough window of time. Because the XML file does not contain isDuration=“true” for the Versailles event, it will be shown differently on the Timeline. The final event is a fixed single point in time when our flight leaves.
Events can have links, images and an HTML content associated with them. The screenshot in Figure 1 shows how this example is rendered by Firefox. Here, I have clicked on the Vierzehnheiligen event to show its image, and below that will be the HTML associated with this event.
A band on the Timeline can be nonlinear. For example, this band could display days as its default unit until it hits a hectic period, at which point it shows hour units for a three-day period before reverting to days as its default unit. This is done using Hot Zones, which are created by calling Timeline.createHotZoneBandInfo() instead of Timeline.createBandInfo() and passing an array of band information.
Listing 2. HTML Showing a Basic Timeline