# Partner server API overview

This section gives more details about the Partner Server API that you will need
as part of the [integration with Google
Transport](https://developers.google.com/travel/transport/guides/partner-integration/getting-started).

To integrate pricing and availability information, partners will need to
implement the Partner API -- in particular, the [GetBulkTripOptions
method](https://developers.google.com/travel/transport/reference/partner-server/get-bulk-trip-options).

At a high level this API uses the following concepts:

## Service class

A service class indicates a standard level of service provided across a group of
different seats/tickets. Traveling options with the same service class should be
a largely equivalent experience (same seat types, amenities, etc) but there may
be some small variations per seat (e.g. additional legroom, window, etc).
Service classes will be used to provide information to users about different
travel options on a particular trip.

## Segment

A segment describes a portion of the user's journey which happens on a single
vehicle, including all attributes that relate to it (e.g. the service class for
that segment).

The [SegmentKey](https://developers.google.com/travel/transport/reference/partner-server/segment-key)
identifies the segment's exact timing and vehicle, but doesn't include any
additional attributes describing the journey on that vehicle.

A trip search generally includes multiple segment keys because a user may have
to use multiple vehicles to reach their chosen destination. Each returned trip
option includes multiple segments that specify the service classes for each
requested segment key.

![Entity Diagram](https://developers.google.com/static/travel/transport/images/entity-diagram.svg)