title: FHIR over HIE repository
body: <p>I need to implement FHIR API over our clinical repository. Since our data is stored from multiple sources, each clinical data/act is represented with a System+ID pair, where system generally represented by OID. e.g. Patient Identifier will be <em>{1.4.7.9.9, MRN123}</em>
  <br>The question is how to tackle such resources from client perspective.<br>
  <br>My options are:<br>
  1. h_t_t_p://BaseUrl/1.4.7.9.9/Patient/MRN123/... - where <strong><em>h_t_t_p://BaseUrl/1.4.7.9.9</em></strong> will be set as the base address and path, and all resources will be evaluated upon it.<br>
  2. h_t_t_p://BaseUrl/Patient/1.4.7.9.9+MRN123/... - concatenation of the System and ID. This approach is most undesired since the consumer generally doesnt aware to the systemId (in option 1 - we'll provide him the baseUrl to be used).<br>
  3. "Standard" URL schema h_t_t_p://BaseUrl/Patient/MRN123/... with the System as custom property in the header of the HTTP request. <br><br>
  Appreciate your thoughts and other options, if any, for tackling that issue<br>
  Thanks</p>