Hermes/Hosa to OSDM (H2O) converter


The aim of this online converter is to build a migration path from the Hermes/Hosa protocol to OSDM. Thus if a railway does not support OSDM yet the Hermes Hosa to OSDM (H2O) Converter ensures that it can connect to railways supporting OSDM. Conversely, if a railway only supports OSDM it guarantees that it can connect to railways supporting Hermes Hosa only.

Initial Analysis

The initial analysis has focused on proving the feasibility of the approach.

Conversion Hermes Hosa to OSDM

This conversion is simple as can be seen in the following table

Use Case Hermes Hosa OSDM
get reservations offers AvailabilityRequest GET /trip-offers(searchCriteria)
get reservations offers BookingRequest with informationOnly=true GET /trip-offers(searchCriteria)
book offer BookingRequest POST /bookings followed by POST /booking/{bookingId}/fulfillments
cancel booking CancelRequest with reason code POST /bookings/{booking}/refundOffers
refund booking CancelRequest POST /bookings/{booking}/refundOffers
(exchange booking) out of scope of MVP out of scope of MVP

SBB has the business need to support this conversion process and is working with Hitrail to build such a converter.

Technical Uses Case

Use Case: Replacement Proposal for trains in exterior inventories.

Solution sketch: If OSDM is asked for a TripOffer where the train it returns an error message containing the inventory. The H2O converter then transform this to a ReplacementProposal.

Conversion OSDM to Hermes Hosa

This conversion is more complex, especially mapping the /trips-offers/ calls to BookingRequest efficiently. If some restrictions on possible reservations are taken however the converter can be realized.

A detailed specification will conceptual work for the conversion is ongoing.

In parallel, the business need for this form of conversion is being evaluated.