17.2FHIR Gateway Configuration Document

The FHIR Gateway uses a JSON document to describe the specific functionality required. Configuration for the gateway consists of the following basic units:

Targets are internal FHIR servers that will ultimately process the requests received by the gateway
Routes are rules that govern which target or targets a request should be forwarded to

This configuration uses the GatewayConfiguration model. An example is shown below.

{
  "targets" : [ {
    "id" : "target1",
    "baseUrl" : "http://fhir1.example.com/api",
    "resourceIdPrefix" : "TGT1-"
  }, {
    "id" : "target2",
    "baseUrl" : "http://fhir2.example.com/api",
    "resourceIdPrefix" : "TGT2-"
  } ],
  "searchRoutes" : [ {
    "id" : "route1",
    "resourceTypes" : [ "Observation", "Patient", "Encounter" ],
    "targets" : [ {
      "targetId" : "target1"
    }, {
      "targetId" : "target2"
    } ],
    "parallel" : true
  } ]
}

17.2.1Defining Targets

The targets array in the gateway configuration uses the GatewayTarget model. It supports the following elements:

Element	Required	Description
id	Yes	An ID for this target. The ID must consist of only letters, numbers, and the characters `._-`. The ID will appear in logs but is not visible to FHIR clients.
baseUrl	Yes	The base URL for the target FHIR server.
httpBasicCredentials	No	Supplies a username and password to be passed to the target server, in the form `username:password`. If credentials should be supplied dynamically (e.g. for OAuth2 support), credentials can instead be supplied using an interceptor.
connectTimeoutMillis socketTimeoutMillis	No	Sets the connect and socket timeout values to use when communicating between Smile CDR and the target server.
resourceIdPrefix	No	If this is supplied, resources from this target will have the given prefix applied to their IDs. This is useful for cases where two target servers are present, and there is a possibility of conflicting IDs (e.g. if both servers can potentially supply a resource with ID `Patient/123`). If prefixes are used, all targets should have a prefix defined, and the prefixes should be short and conformant to the FHIR resource ID rules.
useHttpPostForAllSearches	No	If this is supplied a boolean value of `true`, FHIR searches against this target will always use the HTTP POST format specified in the FHIR Specification, instead of using HTTP GET. Default is `false`.
serverCapabilityStatementValidationEnabled	No	If this is supplied a boolean value of `false`, the gateway will not validate the target server's CapabilityStatement with a request to `/metadata`. Default is `true`.
headersToForward	No	Any headers specified by name will be copied from the incoming client request and added to requests to the target server.

17.2.2Defining Search Routes

The searchRoutes array in the gateway configuration uses the GatewaySearchRoute model. It supports the following elements:

Element	Required	Description
id	Yes	An ID for this route. The ID must consist of only letters, numbers, and the characters `._-`. The ID will appear in logs but is not visible to FHIR clients.
resourceTypes	Yes	Contains a list of resource types (e.g. `Patient`) that this route applies so.
parallel	No	If parallel is set to `true`, the searches to each target server will be performed by the gateway in parallel. If parallel is set to `false`, the searches to each target server will be performed by the gateway in serial, in the order specified by the `targets` array. In both cases, the call by the calling client will not return until all target calls have completed. If not specified, the gateway will perform backing calls sequentially.
targets	Yes	Supplies the list of targets that searches should be directed to.

17.2.3Defining Read Routes

The readRoutes array in the gateway configuration uses the GatewayReadRoute model. It supports the following elements:

Element	Required	Description
id	Yes	An ID for this route. The ID must consist of only letters, numbers, and the characters `._-`. The ID will appear in logs but is not visible to FHIR clients.
resourceTypes	Yes	Contains a list of resource types (e.g. `Patient`) that this route applies so.
targets	Yes	Supplies the list of targets that reads should be directed to. A FHIR read will only be attempted against a single target, and the response (whether successful or unsuccessful) will be returned to the calling client. The target used will be the first target in the list which is able to handle the given request (a target will be skipped if it declares a resource ID prefix that is not present in the request).

17.1 Configuration: Initial Setup