Read Interaction
As per the FHIR spec, the read operation is a simple HTTP GET request, with the ID of the resource in the URL:
Request Example
GET https://clinicals.spineservices.nhs.uk/STU3/[resourceType]/[id] /HTTP1.1
The ID is the unique ID of the resource on Spine - this will have been returned from a create or search interaction.
Response Example
Assuming the resource exists on Spine it will be returned in the HTTP response, with a 200 response code:
HTTP 200 OK
Date: Fri, 25 May 2018 16:09:50 GMT
Last-Modified: Fri, 25 May 2018 16:09:50 GMT
ETag: W/"25777f7d-27bc"
{
"resourceType": "Subscription",
"id": "ea0a4851-8720-4b49-b978-bdcf7102388c",
"meta": {
"lastUpdated": "2018-05-25T16:09:50+00:00",
"versionID": "25777f7d-27bc",
"profile": [
"https://fhir.nhs.uk/STU3/StructureDefinition/EMS-Subscription-1"
]
},
... RESOURCE CONTENT ...
}
Caching READs
When a client does a READ operation to access a specific resource by ID, it may choose to include an If-None-Match header to specify the version ID of the latest version they have of that resource (see the versioning page for details of version IDs) - for example:
GET https://clinicals.spineservices.nhs.uk/STU3/Flag/744eec7d-8951-4722-ad74-dc34e86d4e1a
If-None-Match: W/"25777f7d-27bc"
If the version ID specified in the HTTP header matches the latest held on Spine, a HTTP 304 Not Modified status code will be returned to inform the client that they already have the latest version:
HTTP/1.1 304 Not Modified
Date: Mon, 18 Sep 2015 22:20:01 GMT
If a newer version of the resource does exist, it will be returned as normal, with the newer versionID as described above so the client can update its cache.
Similarly, a client can query for updates that have a Last-Modified data newer than the last time they queried, by specifying a date in an If-Modified-Since HTTP header:
GET https://clinicals.spineservices.nhs.uk/STU3/Flag/744eec7d-8951-4722-ad74-dc34e86d4e1a
If-Modified-Since: Wed, 21 Oct 2015 07:28:00 GMT