New call proposals are in blue.
API levels in green.
Initial minimal REST API
Resource EHR
Method | URL | Parameters | Description | Notes |
---|---|---|---|---|
POST | /ehrs |
| Create a new EHR | HF: How do subjectId and subjectNamespace manifest themselves in the EHR model/resource? HF: We should allow EHR_STATUS and EHR_ACCESS objects so it is not necessary to make additional requests resulting in multiple contributions BL: Good idea. HF: We need audit details for the contribution HF: What is returned in the response? BL: At the moment only: { "meta": { "href": "http://localhost:8082/rest/v1/ehr/f77f9b4a-cfda-414d-aa6c-4f78bcac7601" }, "action": "CREATE", "ehrId": "f77f9b4a-cfda-414d-aa6c-4f78bcac7601" } |
PUT | /ehrs/{ehrId} | As above | Create a new EHR with specified ehr_id | HF: Required when creating an EHR with same ehr_id as in another system |
GET | /ehrs/{ehrId} | Get EHR | HF: Useful to get profile of an EHR. E.g. time created, how many compositions, is there a directory, what was the last contribution etc. | |
DELETE | /ehrs/{ehrId} | Delete an EHR | TB: this isn't possible (well not by an external REST access - it would be an internal admin operation); all you can do is mark an EHR as inactive, which would be a POST (I think) to /ehr/{ehr_id}/ehr_status/other_details/is_active or similar. But even this operation, if it succeeds, is serious - it makes it look like an EHR is deleted, so it's probably not appropriate via any externally visible REST interface. SI: In some countries the patient/client is owner of the data and it has the right (by the law) to ask for a complete (total) removal of all his data, which is more than just an inactive flag. TB: that's true, but doing the delete would require some documentation and/or special permission. I still doubt very much that this could ever be done through a visible REST interface, unless all the proof parameters were provided, and I think these would be too variable to standardise. DB: I agree with SI, this can be a requirement. The authentication/permission is a completely different issue. You could argue that the same kind documentation or special permission would be needed for creating a new composition. BL: I would leave this out of the REST API for the moment. If this is a requirement somewhere it can be performed by other means (special admin interface to the system or similar). DB: I won't leave this out, delete has a clear use case (i.e. opt-out from clinical research) ES: Seems like delete EHR is needed in some cases, so it should be system configurable, we just need to agree on what HTTP status codes/messages to return for different cases. | |
GET | /ehrs/{ehrId}/ehr_status | Retrieve EHR_STATUS | ||
POST | /ehrs/{ehrId}/ehr_status/{versionUid} |
| Update EHR_STATUS | HF: Can we create using this also? BL: Do we need to - would it not be better to create a default status and access when creating EHR (or use the provided ones in the EHR create call body). HF: We need audit details for the contribution HF: We should provide precedingVersionUid or something to support optimistic locking BL: Added versionUid. HF: What is returned in the response? BL: What would you have in response? |
PUT | /ehrs/{ehrId}/ehr_status/... | Update an attribute in ehr_status | TB HF: Do we really want to provide this level of updates, it may result in many contributions when multiple attributes need to be updated | |
GET | /ehrs/{ehrId}/ehr_access | Retrieve EHR_ACCESS | ||
POST | /ehrs/{ehrId}/ehr_access/{versionUid} |
| Update EHR_ACCESS | HF: Can we create using this also? HF: We need audit details for the contribution HF: We should provide precedingVersionUid or something to support optimistic locking HF: What is returned in the response? |
PUT | /ehrs/{ehrId}/ehr_acess/... | Update an attribute in ehr_access | TB HF: Do we really want to provide this level of updates, it may result in many contributions when multiple attributes need to be updated |
Resource FOLDER
Method | URL | Parameters | Description | API level | Notes |
---|---|---|---|---|---|
GET | /ehrs/{ehrId}/directory | Get folder object | R1 | HF: Not really a list of folders, it is the folder object | |
GET | /ehrs/{ehrId}/directory/{folderId}/... | Get folder object | R1 | HF: this shouldn't be limited to single level of folders | |
POST | /ehrs/{ehrId}/directory/{versionUid} | Create or update a folder | HF: We need audit details for contribution HF: We should provide precedingVersionUid or something to support optimistic locking HF: What is returned in the response? | ||
DELETE | /ehrs/{ehrId}/directory/{versionUid} | Deletes a folder | SI |
Resource COMPOSITION
Method | URL | Parameters | Description | API level | Notes |
---|---|---|---|---|---|
POST | /compositions /ehrs/{ehrId}/compositions |
| Create a new composition | HF: If we use the second URL we don't need to specify ehrId as parameter HF: should use the RM term of commit audit description rather than commit comment HF: audit parameters should be group under commit audit parameter HF: What is returned in the response? BL: response is very simple: { "meta": { "href": "http://example.domain.com:8082/rest/v1/composition/bddcedc8-46cc-4df6-8b1a-b05534235f17::example.domain.com::1" }, "action": "CREATE", "compositionUid": "bddcedc8-46cc-4df6-8b1a-b05534235f17::example.domain.com::1" } | |
PUT | /ehrs/{ehrId}/compositions/{objectId} | Create a new composition with specified objectId | HF: Useful when you want to control the object ID | ||
GET | /compositions/{compositionId} | Retrieve a composition | R1 | Do we return a VERSION or a COMPOSITION here? HF: I would prefer VERSION BL: I would prefer a different resource returning versions HF: is compositionId the version UID or object ID? BL: we could have both - one returns exact version specified, the other latest one? HF: Should be able to request version by uid, point in time or at specified contribution? BL: Good idea - can you suggest parameters? | |
GET | /compositions/{compositionId}/version
| Retrieve a VERSION | BL HF: I would prefer the reverse approach to align with RM HF: is compositionId the version UID or object ID? | ||
POST | /compositions/{compositionId} /ehrs/{ehrId}/compositions/{compositionId} |
| Update a composition | HF: is compositionId the version UID or object ID? If version UID then it should be PUT. Having said that, FHIR uses PUT for update using an object ID. BL: I think it should be version uid as it then also gives us optimistic locking HF: We should provide precedingVersionUid or something to support optimistic locking, this could be done using the HTTP If-Match header HF: What is returned in the response? | |
DELETE | /compositions/{compositionId} /ehrs/{ehrId}/compositions/{compositionId} |
| Delete a composition | HF: is compositionId the version UID or object ID? BL: I think it should be version uid as it then also gives us optimistic locking HF: We should provide precedingVersionUid or something to support optimistic locking |
Composition format is the canonical openEHR JSON or XML format. Sample JSON and XML are attached. JSON is using the attribute names based on the RM (snake-case, i.e.: composition.archetype_details.archetype_id) and it also adds the type information - this is the extra attribute "@class" which allows such JSON to be deserialised into proper objects of the target language.
Authentication, sessions should be up to the implementation.
Resource QUERY
Method | URL | Parameters | Description | API level | Notes |
---|---|---|---|---|---|
GET POST | /query
| aql | Execute an AQL | QL1 | GET has a max limit on the query length that will be too short for some queries. (Also if using GET make sure that the server sends proper caching headers.) Should we allow both POST and GET? Added post for querying to allow loooong queries HF: I think we should support POST only |
POST | /q/{query-language} | Generates a query-id and redirects to resulting resource (se rows below) | QL2 | (see http://www.biomedcentral.com/1472-6947/13/57) By default the query-id could be a SHA hash of the query itself (that way repeated identical queries do not need to be re-parsed/stored) If the http-server-log is used as the main source for audit-logging, then the query needs to be stored somewhere since the content of POST is usually not logged in http-logs (The stored query could be inspected using GET q/{query-language}/{query-id}/info/ ). Storing a query (could be an ad-hoc query) for logging purposes does not mean that it needs to be converted to a stored procedure in the database. Manual or automatic routines can be used for deciding when recurring queries (same hash) should be optimized/stored. If we want to support different query languages (or query language versions) we might want urls on the form q/{QUERY_LANGUAGE}/ (examples: /q/AQL/, /q/AQL2/, /q/AQLinXQuery/) HF: Is this an specification alternative to the above or will both be included in the specification? HF: Although I like the idea of the redirect approach, I have some reservation about how javascript clients will react to these redirections HF: Should AQL be assumed in a shortform of this? | |
GET | q/{query-language}/{query-id} | the dynamic parameters defined when query was stored | Executes named query (using dynamic parameters) | QL2 | |
GET | /ehr/{ehrId}/q/{query-language}/{query-id} | the dynamic parameters defined when query was stored | Executes stored query (using named parameters) | QL2 | Discussion: Do we want to allow the possibility to (optionally?) split URIs for single- and multi-patient queries like this (including EHR ID in the URI)? Single-patient queries may have simpler requirements regarding security and may be more efficiently implemented in certain distributed environments. See http://www.biomedcentral.com/1472-6947/13/57 HF: I think this is useful to indicate single-ehr queries from multi-ehr queries. This should also be specified in the original query POST. |
Resource CONTRIBUTION
Method | URL | Parameters | Description | Model | Notes |
---|---|---|---|---|---|
POST | /contributions | Atomically commits a set of changes (composition creates, updates or deletes). | [ { "action": "CREATE", "ehrId": "054ea32b-9ffa-4b00-ba58-a7e92be68087", "composition": { ... } }, { "action": "UPDATE", "compositionUid": "5ab5d99c-ee84-4571-9470-e5fb5002016b::default::1", "composition": { ... } }, { "action": "DELETE", "compositionUid": "1cb4e6bc-860e-4075-9fab-f3c9c113d30d::default::1" } ] | This call might also be under /composition resource. HF: Although the RM doesn't explicitly state this, I think contributions should be related to an EHR. E.g. /ehr/{ehrId}/contributions HF: Where multi-ehr contributions are required, we may consider a transaction mechansim HF: The contribution resource should align more with the RM such as using a cut down representation of the ORIGINAL_VERSION including attributes such as lifecycle_state, preceding_version_id, change_type, data. BL: Even in the current call - where multiple EHRs are concerned contributions should be created for each EHR separately - but the whole operation should still be transactional - so all or nothing. I do agree it would also be nice to have a call with /ehr/{ehrId}/ prefix. Perhaps the name contribution is not right although I hardly imagine somebody would want to POST contributions. | |
Implementation levels (suggestion)
It can be hard for some implementers to support all kinds of calls, we could provide a well specified conformance ladder with basic levels that are easy to add but still are very useful for integrations. Defining R1+W1+Q1 should probably be first priority timewise.
Level | |
---|---|
R1 | Basic read-only. COMPOSITION+FOLDER listing and retrieval. |
R2 | Level 2 read-only. R1 as above plus: Support for listing and retrieval of CONTRIBUTIONS, EHR_STATUS and EHR_ACCESS... |
W1 | Basic write. Writing/updating COMPOSITIONS one by one. Creating new EHRs... |
W2 | Level 2 write. W1 as above plus Writing several changes at once using a CONTRIBUTION... |
QL1 | Basic Query... |
QL2 | Level 2 Query. Named/identified queries with dynamic parameters (allows stored procedures and other optimizations). |
CDS1...? | Clinical Decision Support? |
A system could for example support R1+QL1 another might support R2+W2
TODO-list
- define & describe return model format for all calls (JSON & XML)
- ...including MIME-types suggested by DIPS: application/vnd.openehr+xml or application/vnd.openehr+json
- ...including MIME-types suggested by DIPS: application/vnd.openehr+xml or application/vnd.openehr+json
- define all required parameters (esp commit calls are missing changetype, lifecycle status, ...)
- define additional resources - FHIR like archetype-based resources, conformance?, ...
- Generate machine-readable representation of the REST interface (WADL etc)
Background info/resources
EHRScape API https://www.ehrscape.com/reference.html and https://www.ehrscape.com/api-explorer.html
Applying representational state transfer (REST) architecture to archetype-based electronic health record systems (Erik Sundvall et. al.): http://www.biomedcentral.com/1472-6947/13/57
Corresponding test implementation (LiU-EEE) available at https://github.com/LiU-IMT/EEE/,
html for the index page of the demo server https://github.com/LiU-IMT/EEE/blob/master/src/main/resources/www-file-root/index.html
Possibly interesting java Restlet routers: https://github.com/LiU-IMT/EEE/tree/master/src/main/java/se/liu/imt/mi/eee/ehr
- Ian M has a Word doc [please link/attach it here]
- Koray: Amundsen 'collection type'
- PhD thesis of Roy Fielding, where the REST-architecture was defined and motivated: Architectural styles and the design of network-based software architectures. https://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm
Comments: