Lähdekoodi sivulle GTFS-RT

===Concept===
GTFS-RT is a lightweight API which allows developers to access public transport data via Google Protobuf protocol (over HTTP). Also JSON over HTTP interface is provided. Following GTFS-RT related feeds are implemented:
* Vechile Positions
* Service Alerts

please see https://developers.google.com/transit/gtfs-realtime/ for more information on GTFS-RT.

===Vechile Positions===
* Vehicle positions feed (JSON) is accessible at http://data.itsfactory.fi/journeys/api/1/gtfs-rt/vehicle-positions/json
* Vehicle positions feed (Protobuf) is accessible at http://data.itsfactory.fi/journeys/api/1/gtfs-rt/vehicle-positions

Please note that Protobuf is binary protocol, so your browser probably will trigger download dialog if you use the protobuf URL. Below is a sample of vehicle positions (JSON) feed:
<pre>
{
  "header": {
    "gtfs_realtime_version": "1.0",
    "incrementality": "FULL_DATASET",
    "timestamp": 1452109419
  },
  "entity": [
    {
      "id": "0",
      "vehicle": {
        "trip": {
          "start_time": "21:58:00",
          "start_date": "20160106",
          "route_id": "3"
        },
        "position": {
          "latitude": 61.527477,
          "longitude": 23.706625,
          "bearing": 237
        },
        "vehicle": {
          "id": "TKL_41"
        }
      }
    }
	...
  ]
}
</pre>

The feed provides a JSON "entity" list, where each entity represents a monitored vehicle (bus). For each vehicle, following information is provided:
* trip information: trip's start date, start time and the route id (which in Tampere data corresponds to the line name displayed in the bus head sign)
* position information: the vehicle's latitude and longitude as well as the bearing (in degrees, rotated clockwise, 0 equals north)
* vehicle id, which identifies the actual vehicle (bus) in question

The timestamp field in the header section identifies the time when the response was generated on the server.