The new appointment_google_reserve module allows to make your restaurant (or other booking based service) available to book via Google Maps Reserve. See: https://www.google.com/maps/reserve
https://developers.google.com/actions-center/verticals/reservations/e2e/overview

The integration works alongside with the IAP server, that plays the middleman between the client server and the Google servers.

It is split in three main concepts:

1. The Feed files uploads

See: https://developers.google.com/actions-center/verticals/reservations/e2e/integration-steps/export-feeds

The Google Reserve Service is based on data coming from "feed files", which are manually uploaded once per day via a HTTP call to the IAP servers.

IAP servers will take care of the Merchant and Service feed files based on the merchants that registered for this service.

The merchant/service registration happens via a HTTP call to the IAP server when an appointment.type is configured accordingly.

This is simply done on the appointment.type form by specifying the "merchant" (which is a physical address and some contact details).

The same merchant could be re-used between several appointment.types, for example if a hotel allows booking rooms (1 appointment.type) and massages (with a second appointment.type): the merchant is the hotal (same physical location) and the services are both appointment.types.

The availabilities for all these services are uploaded to the IAP server with a HTTP call when the IAP server requests them.
(See IAP commit message / documentation for more details).

2. The Booking Server

See: https://developers.google.com/actions-center/verticals/reservations/e2e/integration-steps/implement-booking-server

Once a end-user books something from Google Maps Reserve, they (Google) will hit a certain endpoint on the IAP server with the booking details.

IAP then needs to relay this information to the merchant (client)'s, acting as a proxy. The information is then stored accordingly, for example as a new calendar.event record on the related appointment.type.

The same principle is applied to other necessary concepts; modify bookings, cancel bookings, ...

3. Real-time API updates

See: https://developers.google.com/actions-center/verticals/reservations/e2e/integration-steps/real-time-api-updates

This is in a way the same thing as the booking server, but the other way around.

Whenever something happens that modifies availabilities for an appointment, including:
- Creating a booking directly in the backend
- Creating calendar leaves for the appointment resources
- Modifying opening hours
- ...

We need to update the availabilities on Google's side.

In that case, the communication is thus initiated by the client server, that contacts IAP. IAP acts as a proxy again by relaying this information to Google.

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Limitations:
- Only works for auto-assign mode appointment types
- Payment and sales related flow are not implemented.

Task-3083812