title: Map a non-standard JSON data from a REST API into FHIR
body: <p>I'm currently building a REST API 'bridge' that has no database attached and I wanted to convert a JSON response from another API, convert it to FHIR, and then pass it to the client that requests it.</p>
  <p><a href="https://i.stack.imgur.com/O0vMQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/O0vMQ.png" alt="The 'Bridge' API illustration" /></a></p>
  <p>Because of the detailed implementation requirements of FHIR itself, I was thinking to use <code>node-fhir-server-core</code> to do this. Where to implement the non-FHIR-to-FHIR mapping functions? Is it possible to use <code>node-fhir-server-core</code>? If it's not, how to implement FHIR validation/support using plain <code>express</code> application?</p>