Implement real-time vehicle availability sync for a car rental fleet using the OTA Car Rental XML standard

Steps

1. Download the current OpenTravel Alliance (OTA) Car Rental specification (2015B or later) from opentravel.org; identify the OTA_VehAvailRate and OTA_VehRes message pairs you need to implement.
2. Build an OTA_VehAvailRateRQ XML document with RequestedInfo specifying VehicleAvailCore and VehicleAvailInfo; set PickUpLocation and ReturnLocation using IATA or supplier location codes.
3. Send the request to the rental supplier's OTA endpoint over HTTPS with appropriate SOAPAction or REST Content-Type headers; handle the OTA_VehAvailRateRS response, checking the Errors element before parsing rates.
4. Map the AcrissCode in each VehicleAvailCore to display vehicle category (e.g., CCAR = compact car) using the ACRISS 4-character code lookup table published at acriss.org.
5. Construct OTA_VehResRQ with the selected RateKey, customer PII (name, contact, driving licence country), and optionally a corporate ID or promotional code; submit to the reservation endpoint.
6. Parse OTA_VehResRS: check InventoryStatus and extract VehReservation/ConfID for the supplier confirmation number and any deposit or payment instructions.