EDI transactions have ISA segment with Sender ID and Receiver ID identifying who and where sends the transaction. The transaction carries multiple entities such as Eligitbility requests (HIPAA 270), responses (HIPAA 271), claims (HIPAA 837), claim payments (HIPAA 835), enrollments (HIPAA 834), etc.
In FHIR these entities are atomic resources which do not contain Sender and Receiver information, which is quite logical since it is transaction level information not related to entities directly. However, this information is required to organise proper interaction between two parties.
I see MessageHeader resource that carries Sender and Receiver info. Moreover, the type of the fields sender and receiver is just right, it can be either Practitioner or Organization (I assume that for cases when data goes trough clearing house it is organization as well. Basically we can say an exact person or somebody who works at certain company)
The problem is that Claims, EligibilityRequest, Responses, etc. do not refer MessageHeader and when you have some claim in your FHIR server it is impossible to say who sent it for whom it was sent.
I am not sure that MessageHeader is a proper resource here that is intended to carry an analogue of ISA/GS (envelope) segments from EDI. However, I did not find anything that can carry this information. Also, MessageHeader does not have identifier field.
So, the question is how to provide Sender and Receiver information for claims, eligibility requests, etc?