This service receives updates from the DDOT Automatic Vehicle Location (AVL) system and provides a GTFS Realtime Trip Updates feed based on that data.
The service receives 3 basic sets of information from 2 sources:
- the static GTFS package is fetched via HTTP
- static data from the AVL system is posted by a separate tool on the same network as the AVL database
- live adherence data from the AVL system is posted by the same tool
We use the following environment variable for the HTTP transaction:
GTFS_URL: the HTTP URL of the GTFS ZIP file
For example, you might host your latest GTFS package on a server called data.mytransitagency.gov at the path /transit/static/gtfs.zip accessible by the user transitbot with the password supers3cr3t.
The service uses static data from the AVL system to create a translation from AVL IDs to GTFS IDs. The AVL tool posts static data to the following endpoints: /static-avl/blocks, /static-avl/trips, and /static-avl/stops. The service can then map the trip IDs in the live AVL data to GTFS trip IDs. The AVL tool regularly posts that live adherence data to /adherence.
The path for the trip updates feed is /gtfs-realtime/trip-updates. To check the data (i.e. for debugging purposes), a JSON version of the feed is available at /gtfs-realtime/trip-updates.json.
We have designed this app to run on a platform like Heroku.