We test this resource download availability every hour by making an HTTP HEAD request with a timeout of 5 seconds. If we detect a downtime, we perform subsequent tests every 10 minutes, until the resource is back online.

For SIRI and SIRI Lite feeds, we perform a GET request: a 401 or 405 status code is considered successful. In case of HTTP 500, the feed will be considered unavailable, unless the body appears to contain SOAP.