3. Set-Txn HTTP Response Header for Asynchronous Requests

RFC 9967 defines the HTTP response header field Set-Txn for SCIM clients that request asynchronous processing with Prefer: respond-async. When a SCIM response returns HTTP 202 Accepted with no message body, the Set-Txn header field MUST be used. Its value MUST match the txn claim in a later SET.

For asynchronous processing, the HTTP Accept header MUST be ignored. The wait preference SHOULD be supported. The asynchronous response MUST contain no response body. Location MUST be either a URI where the completion SCIM Event Token can be retrieved with HTTP GET, or the normal SCIM Location response defined by RFC 7644. Intermediaries SHOULD NOT insert, modify, or delete Set-Txn. SCIM clients MAY ignore it when completion confirmation is not needed.

For Bulk asynchronous requests, each operation MUST produce an Asynchronous Request Completion Event. The txn value is the original Set-Txn value plus ':' and the zero-based index of the original Operations array. bulkId MUST NOT be used for this purpose. Completion events MAY be generated out of order, but txn operation numbers MUST correspond to original request order. For errors, operation MUST include response, and response MUST contain RFC 7644 Section 3.12 sub-attributes.