...
General Aspects of Interacting with Services
Caching on Searching
Client-side caching is, as caching in general, a mechanism for achieving better performance although it must be applied with caution, especially when used with clinical content.
| Note |
|---|
Use of events for cache invalidation, as described in Caching , might not be immediately available to a client. As described in Caching, caching of information from services in the Clinical Domain is not recommended, with the Patient service being an exception. |
Client-side caching of information from the more stable Administrative Domain must be considered.
In the following, focus is on server-side caching applied upon search operations and how a client can influence it.
eHealth Infrastructure Services with Server-side Caching on Searching
It can generally be assumed that the caching is based on the principles described in HAPI FHIR Search Result Caching. When interacting with custom operations, caching is specific to the operation itself.
Patient Service
Search results will be reused for 1 minute
This cache is used when identical searches are performed (same search parameters)
This means search results can be up to 1 minute stale!
Search results for a particular bundle ID is cached in the database for 1 hour
This cache is used when paging through the result bundle of a particular search
Max value for
max-resultsheader is1000Cache-Control: nostore, max-results=1000
Default page size is 20
Maximum page size is 200
Clients can request a particular page size by setting the
_countparameter
Person$match does not employ any caching
internally, it first searches for a Patient with the provided CRN in the local database (does not use the search result cache, for technical reasons)
If a patient exists, the information from that patient is returned
If a patient does not exist, a request is sent to the CPR registry to lookup the information
The result of this request is not cached or persisted
| Info |
|---|
Infrastructure note: Sticky sessions are not required as the cache is stored in the database. |
Disabling Server-side Caching on Searching
If your use case requires that search results are not cached you have the opportunity to opt out of this using http-headers on your client request:
...
In a HAPI FHIR-based client, opt-out can be achieved like this:
...
Filtering on Searching with Included Resources
...