When we talk about data exchange, we tend to focus on the endpoint, or the intended delivery point of a request. But we can't forget that for every request delivered, it had to originate somewhere first.
A system typically only needs one source to send requests from unless data is exchanged in multiple formats that require different configurations. A source, or the initiating point of a request, is identified in either the header or payload with source-ids.
If you only have one source, it's entirely optional to identify the source-id in an outgoing request.
If your system has multiple sources (e.g., if your system sends and receives data via an API and SFTP), you must identify the relevant source-id in an outgoing request. That way, Redox knows where the request came from, what configuration to apply, and who to notify in case of errors.
To locate the source-id, open the Redox dashboard and navigate to the Developer page. By default, the API keys tab displays. Under the Legacy API keys section, find the key associated with the source you want to use. Use the key ID as the source-id.
If you're using the Data Model API, you can identify the source in the Meta.Source.ID field of the request payload. Remember that this field is only required if you have more than one legacy API key in your environment.
If you're using the FHIR® API, you can identify the source by adding the Redox-Source-Id header to the outgoing request. Remember that this header is only required if you have more than one legacy API key in your environment.