Review the OpenTravel Alliance (OTA) XML message specifications to understand the schema for hospitality messaging; HTNG standards are largely built on OTA specs
Identify the relevant message pairs for your use case: OTA_HotelResNotifRQ and OTA_HotelResNotifRS for reservation notifications, and OTA_HotelResModifyNotifRQ for modifications and cancellations
Build or extend your middleware layer to serialize reservation data into the OTA XML schema and deserialize incoming XML responses into your data model
Implement SOAP/HTTPS transport as most OTA-compliant hotel systems expect SOAP envelopes; ensure your endpoint handles both sending and receiving SOAP messages
Use OTA_HotelAvailNotifRQ for availability updates and OTA_HotelRateAmountNotifRQ for pricing, following the message schema definitions from the OTA specification library
Test message conformance against partner sandbox environments and use an XML schema validator to catch structural errors before production
Known gotchas
OTA XML schemas vary by version (e.g., 2003B, 2014B); a mismatch between the schema version your system sends and what the partner expects causes validation rejection even for structurally correct messages
OTA standards define the schema but not all business rules; each channel manager or PMS vendor extends OTA with proprietary elements, so a message that validates against the base OTA schema may still be rejected by a specific partner
HTNG and OTA do not mandate a transport protocol for all use cases; some partners use SOAP, others use REST with JSON representations of the same concepts, requiring separate adapters for different partners
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