> For the complete documentation index, see [llms.txt](https://developer.rategain.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.rategain.com/ultradirect/ultradirect-transaction-samples-and-usage/using-ultradirect-seamless-a-real-time-transaction.md).
# Using UltraDirect (Seamless, a real-time transaction)
Seamless data describes and provides functionality for the real-time display and processing of reservations directly to the hotel’s central reservation system.
Data returned is held on the hotel’s database and is transient and stateless. Only when a confirmation number is received for a booking, is any information guaranteed.
### System Access
The UAT (User Acceptance Test environment) URL where messages will be posted to during the development and certification phase will be provided after the project kick-off call.
A non-generic URL based on the SGA code assigned to the distribution partner will be used for all transactions other than Bookings, Cancels, and Modifications. An SGA code is an alphanumeric code that uniquely identifies a booking source in the RateGain/UltraDirect (UD) world. This code is assigned by RateGain at the time of the initial implementation.
This unique URL will be created as part of the RateGain environment set-up tasks and will be provided to you after the technical kick-off call.
Bookings, Cancels, and Modifications during the development and certification phase will use the UAT URL:
Security is based on combination of SGA code and pubic IP addresses
The SGA (source code) codes should be communicated to any potential supply partners during commercial negotiations.
Mismatches of SGA code and IP addresses result in the following errors:
“Server Error” IP:
This error is generated when either an invalid SGA code is passed, OR the message comes from a server whose public IP address has not been loaded in the RateGain Access Control List for that SGA code as illustrated below.
Demand Partner Assigned Source Code (SGA) is XX
For example, a customer may have a Source code of "XX" and an IP of 123.123.123.123. There are potentially two ways to be denied:
**· If the example customer passes a code in the Source attribute other than "XX".**
**· If the example customer generates the message from an IP that is not listed.**
Submission of a message with either of the conditions listed above will result in the following error message.
```xml
```
### Mandatory UltraDirect XML Transactions
The following UD XML transaction sets are mandatory for Demand Partners. All demand partners must be able to send the listed requests and consume the associated responses in order to complete UltraDirect (UD) Certification.
**· Enhanced Shopping Transaction (EST)**
**· Rate Rules – \[may be optional for negotiated rates]**
**· Booking**
**· Cancellation**
### Optional UltraDirect (UD) Transactions and features
Modify
Session control for use with bookings, modifications, and/or cancelation. Session control allows for “locking” rates and availability associated with the transaction for up to 15 minutes.
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