LibreTime has a feature which enables your station's show and schedule information to be displayed on remote websites. This feature is included in LibreTime because you would not usually invite the general public to access your LibreTime server directly. If you had very large numbers of people requesting data from the LibreTime server at once, the burst of network traffic might overload the server, potentially disrupting your broadcasts. If carried out maliciously, this network overload is known as a *denial of service attack*.
Instead, your public-facing web server can retrieve the schedule information from the LibreTime API. This information can then be displayed on your broadcast station or affiliate websites by a content management system, such as Sourcefabric's **Newscoop** (<http://newscoop.sourcefabric.org/>). It can be presented using Javascript widgets and styled with CSS, in any format that you require. The **Broadcaster** theme for Newscoop (<https://github.com/newscoop/theme-Broadcaster>) integrates these widgets with ready-to-use styles.
There are two kinds of information that can be retrieved remotely from the LibreTime API without authentication; the metadata for the current show plus the following show (live-info), or the schedule for the current week and the week ahead (week-info). The week-info metadata includes show names, times, and individual show URLs on your public website. That way, the audience for your station can click through from the schedule information to find out more about a particular show, or download a previous show recording that you might have made available.
If your LibreTime server was accessible at https://libretime.example.com the live show information could be retrieved by your web server using this URL:
In this case, the metadata returned would be in a different format from the above example, something like the following. To keep the example short, this particular schedule export only contains four shows on a Monday. A full weekly schedule export would contain a great deal more text.
If you see the message *You are not allowed to access this resource* when attempting to display schedule information in your web browser, log in to the LibreTime administration interface, click *System* in the main menu, then *Preferences*. Set **Allow Remote Websites To Access "Schedule" Info?** to **Enabled**, click the **Save** button, then refresh the browser window opened on the schedule export URL. If you do not wish to make schedule information available to the public, set this option to **Disabled** instead.
If the LibreTime server is behind a firewall, or you want to protect the LibreTime server from large numbers of schedule requests, you may wish to cache the schedule information on a public-facing or intermediate server. You can then create a firewall rule that only allows the schedule server to connect to the LibreTime server, in addition to any remote users of the LibreTime web interface.
Your system administrator can set up schedule caching on a standard Apache and PHP enabled web server with the *curl* program installed, using the following steps:
1. Create a shell script on the schedule server (schedule.example.com) that polls the remote LibreTime server (libretime.example.com), and writes the metadata returned into a pair of local temporary files:
The schedule server will now be serving the same show information as the LibreTime server, with a cache lifetime of one minute. You can adjust the cache lifetime by altering the frequency of the cron job that polls the LibreTime server.
If there is no inbound access to the LibreTime server at all, an FTP script can be used to push cached schedule data from LibreTime to an external web server. The standard ftp command should be available on the LibreTime server and the external web server should have a suitably restricted FTP account set up. After following steps 1 and 2 above to export schedule data to a pair of temporary files on the LibreTime server, create a new script on the LibreTime server to automatically make the upload:
Replace host, user and password values with appropriate values for your external web server:
#!/bin/sh
HOST='website.example.com'
USER='ftp_user'
PASSWD='ftp_password'
ftp -n -v $HOST <<EOT
user $USER $PASSWD
ascii
prompt
put /tmp/airtime-week-info
put /tmp/airtime-live-info
bye
EOT
Then make the new script executable and create a cron job to launch it every minute, as in step 8 above. Steps 3 to 7 above should be carried out on the external web server so that it can convert the two temporary files uploaded via FTP into public schedule data.
