Position paper - Timesheets

The W3C Workshop on Web Applications and Compound Documents

Teppo Jalava, Teppo.Jalava@hut.fi
Mikko Pohja, Mikko.Pohja@hut.fi
Helsinki University of Technology


Synchronized Multimedia Integration Language (SMIL) is widely used for authoring multimedia presentations. To create a presentation in SMIL consisting of other XML documents is not very handy, though. In addition to images, audio and video, a presentation can contain elements from other XML documents, like XHTML. To include a formatted HTML text element into a SMIL document, an external HTML document must be added to the timeline and the actual formatting of the element is done in the external document. A better idea would be to create one XML document with the contents and handle the formatting and timing of the document separately. For formatting, one can use e.g. Cascading Style Sheets. For temporal structure, Timesheets language has been proposed [1]. 


Timesheets can be seen as a temporal counterpart for Cascading Style Sheets. Whereas CSS defines the spatial layout of the document and formatting of the elements, Timesheets specify what elements are active at a certain moment. And as with CSS, Timesheets can be reused in multiple documents, which can provide a common temporal layout for multimedia presentations with different contents but identical storylines. The document can be shown in a user agent even if the Timesheets are not supported, since the contents and the layout are still governed by the document itself. Of course, the temporal aspect of the document is then lost, since all the elements are active all the time.

A simple example of the Timesheets is shown below. It shows a general XHTML document that could be, for example a single slide from a slideshow. When the document is viewed, first only the title "Introduction" and the page number are shown. Then, after two seconds, the text of the first bullet is shown, followed by the next bullet every two seconds. The placement and styling of the elements are specified in the CSS, the Timesheet only specify the visibility of the elements at a given moment in time.

<style type="text/css">

<item select="#bullet1" begin="2s"/>
<item select="#bullet2" begin="4s"/>
<item select="#bullet3" begin="6s"/>
<item select="#bullet4" begin="8s"/>

<div id="content">
<p id="title">Introduction</p>
<p id="bullet1">o Some intro to WLAN</p>
<p id="bullet2">o Some intro to WLAN</p>
<p id="bullet3">- Subbullet</p>
<p id="bullet4">- Subbullet</p>
<p id="pagenum">2</p>

A simple example of  an XHTML document with Timesheets

A basic implementation of Timesheets is being developed at HUT under the X-Smiles project (http://www.xsmiles.org). X-Smiles is an XML browser, which supports several XML specifications and general XML documents styled by CSS. In addition, temporal styling of a document is supported through Timesheets.

The Timesheet implementation is based on the work by W. Kate et. al. [1] and W3C Recommendation of SMIL 2.0. Currently, the implementation supports the basic SMIL functionality, including parallel and sequential time containers, events and prefetching contents. A few demos has also been created as a proof of concept.


[1] Kate, W. et. al., "Timesheets - Integrating Timing in XML", WWW9 Workshop: Multimedia on Web, 2000.