clj-hl7-fhir/README.md

clj-hl7-fhir

HL7 FHIR JSON client for use in Clojure applications. This is a fairly low-level wrapper over the HL7 FHIR RESTful API and does not include any model classes (or anything of the sort) for the various HL7 resources. FHIR API calls wrapped by this library work with JSON data represented as Clojure EDN data.

The primary goal of clj-hl7-fhir is to make getting data into and out of an HL7 FHIR server as simple as possible, without needing to know much about the RESTful API (the URL conventions working with HTTP status codes, reading back data from paged bundles, encoding search parameters, etc). How you create and/or read the HL7 data and what you do with it is beyond the scope of this library.

Leiningen

[clj-hl7-fhir "0.1"]

TODO

This library is still early along in development, and some important features are missing at the moment:

• Authentication support
• Remaining API calls
  • history
  • validate
  • transaction
  • conformance

Usage

Most of the basic RESTful API operations are supported currently.

• read
• vread
• search
• create
• update
• delete

All of the functions that wrap FHIR API calls are located in clj-hl7-fhir.core:

(use 'clj-hl7-fhir.core)

base-url

All core API functions take a base-url parameter. This is the Service Root URL for which all API calls are made to.

For example, to use UHN's HAPI FHIR test server:

(def server-url "http://fhirtest.uhn.ca/base")

read / vread

There are a couple options for reading single resources by ID.

get-resource takes the resource type and ID and returns a FHIR resource. Alternatively, you can specify a relative resource URL instead of separate type and ID arguments. You can also optionally include a specific version number to retrieve.

get-resource-bundle works similarly to get-resource, except that it returns a FHIR bundle instead of a resource.

Examples

; reading a single resource by ID
(get-resource server-url :patient 37)
=> {:address
    [{:use "home"
      :line ["10 Duxon Street"]
      :city "VICTORIA"
      :state "BC"
      :zip "V8N 1Y4"
      :country "Can"}]
    :managingOrganization {:resource "Organization/1.3.6.1.4.1.12201"}
    :name [{:family ["Duck"] 
            :given ["Donald"]}]
    :birthDate "1980-06-01T00:00:00"
    :resourceType "Patient"
    :identifier
    [{:use "official"
      :label "UHN MRN 7000135"
      :system "urn:oid:2.16.840.1.113883.3.239.18.148"
      :value "7000135"
      :assigner {:resource "Organization/1.3.6.1.4.1.12201"}}]
    :telecom
    [{:system "phone" :use "home"}
     {:system "phone" :use "work"}
     {:system "phone" :use "mobile"}
     {:system "email" :use "home"}]
    :gender
    {:coding
     [{:system "http://hl7.org/fhir/v3/AdministrativeGender"
       :code "M"}]}
    :text
    {:status "generated"
     :div
     "<div><div class=\"hapiHeaderText\"> Donald <b>DUCK </b></div><table class=\"hapiPropertyTable\"><tbody><tr><td>Identifier</td><td>UHN MRN 7000135</td></tr><tr><td>Address</td><td><span>10 Duxon Street </span><br/><span>VICTORIA </span><span>BC </span><span>Can </span></td></tr><tr><td>Date of birth</td><td><span>01 June 1980</span></td></tr></tbody></table></div>"}}
     
; trying to read a non-existant resource
(get-resource server-url :patient 9001)
=> nil

; reading a specific version of a resource
(get-resource server-url :patient 1654 :version 3)
=> { 
    ; ... similar to the above example resource return value ... 
    }

; trying to read an invalid resource
(get-resource server-url :foobar 42)
ExceptionInfo FHIR request failed: HTTP 400  clojure.core/ex-info (core.clj:4403)

search

Searching for resources is performed via search. It returns a FHIR bundle containing all the resources that matched the search parameters given. If you provide no search parameters then all resources of the type given will be returned (though they will be paged likely, as per the FHIR specs).

Search parameters are specified as a vector, where each parameter should be defined using the helper functions:

Helper function	Description and usage example
eq	Equals (eq :name "smith")
lt	Less then (lt :value 10)
lte	Less then or equal to (lte :date "2013-08-15")
gt	Greater then (gt :value 10)
gte	Greater then or equal to (gte :date "2013-08-15")
between	Between (between :date "2013-01-01" "2013-12-31")

Note that you can also use a plain old string for parameter names instead of keywords if you wish

If a parameter value needs to include a namespace, you can use the namespace helper to help properly encode this information in the search parameters:

(eq :gender (namespaced "http://hl7.org/fhir/v3/AdministrativeGender" "M"))

There are also a few helper functions in clj-hl7-fhir.util for converting java.util.Date objects into properly formatted ISO date/time strings that match FHIR specifications:

Function	Example output
->timestamp	2014-08-05T10:49:37-04:00
->local-timestamp	2014-08-05T10:49:37-04:00
->date	2014-08-05

As mentioned above, search results will be returned in a FHIR bundle, which contains a vector of all the matching resources. For convenience, you can use collect-resources to return a sequence of just the resources by passing/threading the results from search into this function.

(collect-resources
  (search server-url ...)

Larger search results will be paged. Some helper functions are available to make working with paged search results easier:

• fetch-next-page takes a search result bundle and uses it to get and return the next page of search results. If there are no more pages of results, returns nil.
• fetch-all takes a search result bundle, and fetches all pages of search results, and then returns a bundle which contains the full list of match resources.
• search-and-fetch convenience function that is the same as doing: (fetch-all (search ...)). Takes the same arguments as search.

Examples

; list all patients
; (http://server-url/Patient)
(search server-url :patient [])

; find all patients with name "dogie"
; (http://server-url/Patient?name=dogie)
(search server-url :patient [(eq :name "dogie")])

; find all female patients
; (http://server-url/Patient?gender=http%3A%2F%2Fhl7.org%2Ffhir%2Fv3%2FAdministrativeGender%7CF)
(search server-url :patient [(eq :gender (namespaced "http://hl7.org/fhir/v3/AdministrativeGender" "F"))])

; also works (depending on the exact data and server spec compliance)
; (http://server-url/Patient?gender=F)
(search server-url :patient [(eq :gender "F")])

; find all male patients with a birthdate before Jan 1, 1980
; (http://server-url/Patient?birthdate=%3C1980-01-01&gender=M)
(search server-url :patient [(eq :gender "M")
                             (lt :birthdate "1980-01-01")])

; search using an invalid parameter (unrecognized by the server)
; (http://server-url/Patient?foobar=baz)
(search server-url :patient [(eq :foobar "baz")])
ExceptionInfo FHIR request failed: HTTP 400  clojure.core/ex-info (core.clj:4403)

Error Handling

All API functions throw exceptions via ex-info when an unexpected error response is returned from the HL7 FHIR server. An "unexpected error response" is anything that is not defined to be part of the particular operation's successful result(s). e.g. a "read" operation that returns an HTTP 400 or HTTP 500 status instead of HTTP 200.

When this type of response is encountered, an exception is thrown which will contain the response, which can be obtained in your exception handler via ex-data. If the response is detected to be a FHIR OperationOutcome resource, it will be parsed and set as the response, otherwise the raw response body is set in the exception.

; trying to read an invalid resource
(get-resource server-url :foobar 42)
ExceptionInfo FHIR request failed: HTTP 400  clojure.core/ex-info (core.clj:4403)

; more detailed error information can be obtained via ex-data
(try
  (get-resource server-url :foobar 42)
  (catch Exception e
    (let [operation-outcome (ex-data e)]
      ; TODO: proper error handling goes here
      operation-outcome)))
=> {:status 400
    :fhir-resource? true
    :response
    {:resourceType "OperationOutcome"
     :text
     {:status "empty"
      :div
      "<div>No narrative template available for resource profile: http://hl7.org/fhir/profiles/OperationOutcome</div>"}
     :issue
     [{:severity "error"
       :details
       "Unknown resource type 'Foobar' - Server knows how to handle: [User, Condition, Supply, GVFVariant, Organization, Group, ValueSet, Coverage, ImmunizationRecommendation, Appointment, MedicationDispense, MedicationPrescription, Slot, AppointmentResponse, MedicationStatement, SequencingLab, Questionnaire, Composition, OperationOutcome, Conformance, Media, Other, Profile, DocumentReference, Immunization, Microarray, OrderResponse, ConceptMap, Practitioner, ImagingStudy, GVFMeta, CarePlan, Provenance, Device, Query, Order, Procedure, Substance, DiagnosticReport, Medication, MessageHeader, DocumentManifest, Availability, MedicationAdministration, Encounter, SecurityEvent, GeneExpression, SequencingAnalysis, List, DeviceObservationReport, Claim, FamilyHistory, Location, AllergyIntolerance, GeneticAnalysis, Observation, RelatedPerson, Specimen, Alert, Patient, Remittance, AdverseReaction, DiagnosticOrder]"}]}}

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.