FHIR Requests, Responses, and Payloads
This topic discusses the requests and responses used by FHIR servers when a production is not in use.
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For information about requests and responses when a production is in use, see FHIR Production Requests and Responses.
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For information about requests and responses used by the InterSystems FHIR client, see FHIR Clients.
Non-Production FHIR Server Requests and Responses
For a FHIR server that does not use an interoperability production:
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The message class that the server architecture uses to pass HL7® FHIR® requests is HS.FHIRServer.API.Data.RequestOpens in a new tab.
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The message class that the server architecture uses to pass responses from the server to the FHIR client where the request originated is HS.FHIRServer.API.Data.ResponseOpens in a new tab.
Accessing FHIR Payloads
By default, when a FHIR request is received by the REST handler, it stores the FHIR payload in the Json property of a Request object (HS.FHIRServer.API.Data.RequestOpens in a new tab), which automatically puts the JSON structure into a dynamic object. FHIR requests that contain XML are converted to JSON before being represented as a dynamic object in the Json property. Responses from the FHIR server (HS.FHIRServer.API.Data.ResponseOpens in a new tab) also contain a Json property for FHIR data.
Working with FHIR data begins by getting access to the Json property of the request or response. Once you have the FHIR payload, you can manipulate it as a dynamic object. For examples, see FHIR Data.
Retrieving FHIR Resources Using an ObjectScript Application
If an ObjectScript application needs to retrieve resources from the Resource Repository, it can build a non-production request object (HS.FHIRServer.API.Data.RequestOpens in a new tab) before dispatching it to the endpoint’s Service. If the application is retrieving data, it is returned as the non-production response object (HS.FHIRServer.API.Data.ResponseOpens in a new tab). For more details, see Direct Calls to DispatchRequest.
Setting the Client-Visible URL
In some cases—notably, when requests are forwarded to a FHIR endpoint through a proxy—the URL at which the FHIR server received a request may differ from the URL which was originally requested by a REST client.
In such cases, the FHIR Server’s rest handler determines the client-visible base URL from the content of a request object’s FORWARDED or X-FORWARDED HTTP headers. This logic is implemented by the GetBaseURL()Opens in a new tab class method of the HS.FHIRServer.Util.BaseURLOpens in a new tab class.
If your FHIR server must construct the client-visible URL according to a different logic, simply define a custom GetBaseURL() in the HS.Local.FHIRServer.Util.BaseURLOpens in a new tab class. A method defined in this class will override the original.
