Availability, Rates, and Inventory (ARI)

While often grouped together as a single data feed, each component of ARI controls a specific aspect of the commercial offer:

• Availability (Status & Restrictions): This does not just mean “open” or “closed.” It includes complex restrictions (often called fences):

Stop Sell: A hard close for a specific date.

MinLos: Minimum Length of Stay (i.e., “Must stay 3 nights”).

CTA/CTD: Closed to Arrival/Closed to Departure.

• Rates (Pricing): The monetary value attached to a specific date and room type. This includes currency code, base amount, and tax inclusion flags. Modern revenue management is based on changing this R component very rapidly—multiple times a day.
• Inventory (Count): The physical number of units for sale (e.g., “5 Standard Rooms remaining”). This number must be decremented in real-time for all channels to avoid overbooking.

In the world of connectivity (via channel managers or switches) now using XML or JSON messaging, Availability, Rates, and Inventory (ARI) is handled via message exchange.

• Delta Updates: To save bandwidth, systems rarely send the full calendar every time. They send Delta updates — packets of data that contain only the data that has changed (like “Change Rate for June 1st to $150”).
• Caching: Because OTAs (like Expedia or Booking.com) are receiving millions of search queries per minute, they cannot ask the hotel’s system for ARI in real-time for every single search: it would crash the hotel’s server. Instead, OTAs cache a copy of the ARI in a Cache.
• Latency Issues: If the ARI update from the hotel is slow to transfer to the OTA’s cache, a customer might see a room as “Available” ($100) that is really “Sold Out.” This causes a booking failure or price jump on checkout.