Displaying auto-updating data

Another useful interface enhancement is the ability to display data that is constantly updated at a set timed interval. For example, this could be used to update a list of news headlines every five minutes, or update the display of live stock data every minute.

In this recipe, we will take the basic example of a clock, displaying the full date and time on the page, and update it every second using the polling extension to the DataSource utility. This technique can be used to display any data from any data source, and update it as frequently as we like.

How to do it...

In this example, we will set up a very simple PHP page, autoupdate.php, containing only one placeholder div in which we will display the current date and time:

<?php
require_once(dirname(__FILE__) . '/../config.php');
$PAGE->set_context(get_context_instance(CONTEXT_SYSTEM));
$PAGE->set_url('/cook/autoupdate.php');
$PAGE->requires->js('/cook/autoupdate.js', true);
echo $OUTPUT->header...