Allow remapping of agency_ids in GTFS-rt service alerts

[barbeau]

We need to be able to re-map agency_ids that appear in GTFS-rt Service Alerts to match re-mapping done with GTFS data. Currently, the GTFS-rt spec only allows the agency_id field to be supplied in Service Alerts, so this only applies to Service Alerts.

Currently, the GtfsRealtimeSource config in data-sources.xml looks like this:

<bean class="org.onebusaway.transit_data_federation.impl.realtime.gtfs_realtime.GtfsRealtimeSource">
  <property name="tripUpdatesUrl" value="http://url/to/gtfs-realtime/trip-updates" />
  <property name="vehiclePositionsUrl" value="http://url/to/gtfs-realtime/vehicle-positions" />
  <property name="alertsUrl" value="http://url/to/gtfs-realtime/alerts" />

  <!-- Optionally configure the agency id we use to match incoming data -->
  <property name="agencyId" value="SomeAgencyId" />
</bean>

The agencyId property above is used to associate the GTFS-rt feeds with a particular agencyId from the GTFS data. However, currently the agencyId field in the GTFS-rt Service Alerts feed takes precedence, and as a result OBA can't match the alerts to the correct agency. Additionally, the GTFS-rt specs allow more than one agency to be represented in the same Service Alerts feed (hence the agency_id field), so we actually need a way to remap multiple agencyIds in the same Service Alerts feed.

We propose to implement this remapping in the data-sources.xml config file as a new alertAgencyIdMap property for GtfsRealtimeSource:

<bean class="org.onebusaway.transit_data_federation.impl.realtime.gtfs_realtime.GtfsRealtimeSource">
  <property name="tripUpdatesUrl" value="http://url/to/gtfs-realtime/trip-updates" />
  <property name="vehiclePositionsUrl" value="http://url/to/gtfs-realtime/vehicle-positions" />
  <property name="alertsUrl" value="http://url/to/gtfs-realtime/alerts" />

  <!-- Optionally configure the agency id we use to match incoming data -->
  <property name="agencyId" value="SomeAgencyId" />

  <!-- **Remap the following agencyIds in the GTFS-rt Service Alerts feed** -->
    <property name="alertAgencyIdMap">
        <map>
            <entry key="agencyIdInFeed" value="remappedAgencyId" />
        </map>
    </property>
</bean>

For example, here's a GTFS-rt Service Alerts feed:

entity {
  id: "1"
  alert {
    informed_entity {
      agency_id: "1"
    }
    header_text {
      translation {
        text: "new 29: 29"
        language: "
        ...

We need to remap the agency_id of 1 to PSTA. We would configure this as follows:

<bean class="org.onebusaway.transit_data_federation.impl.realtime.gtfs_realtime.GtfsRealtimeSource">
  <property name="tripUpdatesUrl" value="http://url/to/gtfs-realtime/trip-updates" />
  <property name="vehiclePositionsUrl" value="http://url/to/gtfs-realtime/vehicle-positions" />
  <property name="alertsUrl" value="http://url/to/gtfs-realtime/alerts" />

  <!-- Optionally configure the agency id we use to match incoming data -->
  <property name="agencyId" value="PSTA" />

  <!-- **Remap the following agencyIds in the GTFS-rt Service Alerts feed** -->
    <property name="alertAgencyIdMap">
        <map>
            <entry key="1" value="PSTA" />
        </map>
    </property>
</bean>

@cagryInside has tested this implementation and it works. He'll submit a PR shortly. Any feedback is welcome.

@sheldonabrown This is a solution to the issue we discussed via email.

[barbeau]

I'm re-opening, as it looks like we missed re-mapping the agency_ids in the situationIds list.

For example, see the following REST API request:
http://app.staging.obahart.org/api/where/arrivals-and-departures-for-stop/PSTA_4077.json?key=TEST

The response:

data: {
    entry: {
        arrivalsAndDepartures: [
        ...
        ]
    }
        situationIds: [
        "1_1",
        "1_2"
        ]
        stopId: "PSTA_4077"
    },
    references: {
        ...
        situations: [
            {
                allAffects: [
                    {
                        agencyId: "PSTA"
...

You can see that the agencyId in the references element has been remapped, but the situationIds list in the entry element has not.

@cagryInside Could you please take a look and submit another PR fixing this? Thanks!

[barbeau]

Looks like the above was a data-sources.xml config issue (there was still a reference to <property name="agencyId" value="1" />). After this was changed to PSTA, everything looks good. So, this issue is fixed.