FHIR for Architects and Developers - New Zealand Seminar, June 2014


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An more advanced demonstartion of FHIR presented by HL7 New Zealand to a local audience

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  • Published as HTML
    Published using validation process that performs consistency checks – like a software build
    Really shouldn’t require much guidance to read, but a few things to call out
    Objective of spec is developer can skim and decide in < day

    Show the search (search for tag)
  • You’re a message broker routing and translating between v2, v3 and FHIR
    Your app interfaces with a PHR using FHIR natively
    Your application can communicate using FHIR, but your software uses a proprietary RDBMS
    Use FHIR as the common language for a Vendor Neutral Archive
    …Or a combination….
    You might see data as a nested structure of XML, a series of tables with keys, class-diagrams….

  • FHIR can be your shared persistence layer – nice granularity for storage, extensions for handling “extra” stuff easily

    FHIR can be the common model for your mapping layer

    FHIR can be the logical model used for decision support, both to expose your data to the decision support engine as well as to define rules (work in progress with vMR-CDS and CQI)
  • Review
  • Chained – query across referenced resources - GET [base-url]/DiagnosticReport?subject.name=peter

    Tags: security, profile, general
    Examples if have time


    Standard search parameters
  • Example of sync DocumentRefrences – a DHB could maintain a local cache
  • * the deletion operation should be understood as deleting the record of the resource, with nothing about the state of the real-world corresponding resource implied.
  • * Now, if you query for /server.org/fhir/patient/@33, you get a 410
  • * The resource returns back to life!
  • Not talking about REST in general, but rather FHIR’s implementation of REST
  • Todo: more specifics from Grahame.

    Removed: No natural “server” or no fixed network location
  • Note that easier in NZ as we locked CDA down.
  • A Document, no matter how nested, is flattened to a list of entries, the Document’s header being the first.
    The document header (and any other the other resources) refer to each other using normal references to reflect the document’s nesting.
    Of course, there may be a digital signature (on the whole Bundle) to attest to the content of the document.
  • Talk about how functions as the CDA header
  • Furore server – id NZ100
    Talk about conversion
  • You can retrieve any patient using a GET on the patient’s id, which is just an url on the server: /fhir/Patient/<id>
    We have our own MIME-type: “application/xml+fhir” and “application/json+fhir”
  • Mobile, social web, green field are most likely adopters, though significant interest from other quarters
  • This is not only the URL you use to retrieve the resource, it’s also its id.
    All URL’s in FHIR are case-sensitive (and so is the id)
    It is *metadata*, you won’t find this in the Resource’s definition

  • Resource Id’s (=URLs) are infrastructural id’s, they differ from “business” identifier.
    Many Resources also have business identifiers, they are explicitly modeled, like Patient.identifier (even more than one identifier possible!)
    Business identifiers are completely separate from technical resource id’s
  • Only the Resources are user-definable, other types are “built-in”
    Derived primitives are patterns -> validation consists of regexp matching
    Constrained types are defined using invariants (OCL, Xpath, prose) -> validation using schematron, code
    Narrative and Extension are both ONLY used in Resources
    Resources can use both (derived) primitives and composite datatypes in its definitions
    Infrastructural types need special handling, not general-purpose types
  • Resources SHOULD always contain narrative to support human-consumption as a fallback. However, in a strictly managed trading systems where all systems share a common data model and additional text is unnecessary or even a clinical safety risk, the narrative may be omitted. 

    generated The contents of the narrative are entirely generated from the structured data in the resource.
    extensions The contents of the narrative are entirely generated from the structured data in the resource and some of the content is generated from extensions.
    additional The contents of the narrative contain additional information not found in the structured data.
    empty the contents of the narrative are some equivalent of "No human-readable text provided for this resource".
  • References can be in the same bundle, on the same server, on a different server
  • Can expand value set
  • See how the resource meta-data is mapped to equivalent Atom members
    Author is required by atom, so you’ll have to keep track who authored the resource, which might well be the user that POSTed it to your RESTful endpoint
    Summary is optional, but it is easy to fill it with the Resource’s <text> (human readable narrative), so Feed readers have a way to display the contents of a resource. Yes, this means the summary is present twice in the entry.
    All elements you see here are Atom spec, not FHIR
  • See how the resource meta-data is mapped to equivalent Atom members
    Author is required by atom, so you’ll have to keep track who authored the resource, which might well be the user that POSTed it to your RESTful endpoint
    Summary is optional, but it is easy to fill it with the Resource’s <text> (human readable narrative), so Feed readers have a way to display the contents of a resource. Yes, this means the summary is present twice in the entry.
    All elements you see here are Atom spec, not FHIR
  • Imagine that all resources in a single bundle
    Links maintain references
    Comment on new recources (cid: id’s)
  • Specify data types – eg if deceased then must be datetime not boolean
  • A ‘hierarchy’ of profiles
    The higher up the more likely to be reused

  • Really any FHIR element (Resource, Datatype, Primitive) can be extended. Just nest an <extension> element under the thing you want to extend
    You should be able to go to the formal definition endpoint and get the definition of the extension.
    Note: birth order is already provided for in FHIR through the multipleBirthInteger

  • Especially in HTTP space lots of work done – why re-invent?
    Application ‘knows’ user and rights, can deliver content as appropriate
    No concept of an ‘incomplete’ response to a query (could define tag in bundle if required)
  • FHIR for Architects and Developers - New Zealand Seminar, June 2014

    1. 1. FHIR for Architects and Developers Acknowledgements • Lloyd McKenzie • Ewout Kramer • Grahame Grieve Agenda • Architectures • Paradigms • Resources • Bundles • Profiles & Extensions • Server Notes • Workflow • Security • Tools and Help • Next steps in New Zealand
    2. 2. Page 2 • HL7 New Zealand The Spec: Hl7.org/fhir 2
    3. 3. Architectures
    4. 4. Page 4 • HL7 New Zealand Architectures • FHIR makes no assumptions about the architectural design of systems • You can use it for – Light or heavy clients – Central server or peer-to-peer sharing – Push or pull – Query or publish/subscribe – Loosely coupled or tightly coupled environments  With history tracking (versions) or without 4
    5. 5. Page 5 • HL7 New Zealand Some possibilities 5 FHIR Broker v3 v2 PHR FHIR App Comm. Interface DB FHIR
    6. 6. Page 6 • HL7 New Zealand Repository model Vendor Neutral Repository FHIR HIS GP PACS SystemX Gateway FHIR FHIRFHIRFHIR
    7. 7. Page 7 • HL7 New Zealand Beyond exchange 7 v3 v2 Other X12 Broker v3 v2 FHIR Repository Decision Support FHIR FHIR Other
    8. 8. Page 8 • HL7 New Zealand Bottom Line • FHIR is a set of tools – Defined resources – Extensibility mechanism – Versioning – Multi-paradigm – Set of standard interfaces – Support for complex services • Primary purpose is interoperable data exchange • However, it can be leveraged in many ways – Many we haven’t even thought of yet . . . 8
    9. 9. Paradigms revisited
    10. 10. Page 10 • HL7 New Zealand Paradigms • FHIR supports 4 interoperability paradigms 10 REST Documents Messages Services What should you use when?
    11. 11. Paradigms: REST
    12. 12. Page 12 • HL7 New Zealand REST • Simple, out-of-the-box interoperability • Leverage HTTP: GET, POST, etc. • Pre-defined operations – Create, Read, Update, Delete – Also: History, Read Version, Search, Updates, Validate, Conformance & Batch (Transaction) • HTTP Headers for various options – Like resource format or location • Response codes to indicate outcome – OperationOutcome Resource • Works best in environments where control resides on client side and trust relationship exists 12 Rest
    13. 13. Page 13 • HL7 New Zealand Creating & Updating • POST vs PUT • Headers – Request • Content-type • Location (for version aware) – Response • Content-type • Others... • Status messages – Standard HTTP • OperationOutcome • Version aware updates
    14. 14. Page 14 • HL7 New Zealand Querying by REST • Base queries – Simple GET against a resource type – GET [base]/Patient?name=eve • Defined rules for query parameters • More complex – _include – Tags • Queries across reference – Eg conditions for a patient – GET [base]/Condition?subject=84238862 – Chained queries • Compartments – Syntactic sugar – GET [base]/Patient/84238862/Condition
    15. 15. Page 15 • HL7 New Zealand Synchronizing • History of all resources on server – GET [base]/fhir/_history • History of all patient resources on server – GET [base]/Patient/_history • History of specific patient on server – GET [base]/Patient/1/_history • A history of all changes: inserts, updates and deletions, ordered by newest first • Limit with _since and _count
    16. 16. Page 16 • HL7 New Zealand What’s a ‘deleted’ Resource? • Delete using DELETE verb • Trying read operations will return in a 410 (Gone) result in stead of 404 (Not Found) • The resource will not be returned by the search operation. • You can “undelete” by doing an update (PUT) with fresh content • Just a “marker” in a resource’s history
    17. 17. Page 17 • HL7 New Zealand Version history - deletions 33, v12 – 2012-12-04 33, v13 – 2012-12-05 33, v14 – 2012-12-08 /server.org/fhir/Patient/33/_history/12 /server.org/fhir/Patient/33/_history/14 /server.org/fhir/Patient/33/_history/13 /server.org/fhir/Patient/33/_history/15 /server.org/fhir/Patient/33 33, v15 – 2012-12-09 33, v16 – 2012-12-10 DELETION /server.org/fhir/Patient/33/_history/16
    18. 18. Page 18 • HL7 New Zealand Version history - revival 33, v13 – 2012-12-05 33, v14 – 2012-12-08 /server.org/fhir/Patient/33/_history/14 /server.org/fhir/Patient/33/_history/13 /server.org/fhir/Patient/33/_history/15 /server.org/fhir/Patient/33 33, v15 – 2012-12-09 33, v16 – 2012-12-10 /server.org/fhir/Patient/33/_history/16 33, v17 – 2012-12-11 /server.org/fhir/Patient/33/_history/17
    19. 19. Page 19 • HL7 New Zealand Batch • POST a bundle to server root • Processed as a transaction – All succeed, or all fail • All operations supported • Different to /message endpoint – /message allows custom server processing – Batch is a sequence processed as a transaction
    20. 20. Playing with FHIR
    21. 21. Page 21 • HL7 New Zealand Test Servers • Servers – At least 4 to choose from – http://spark.furore.com/fhir/Patient/nz100 – http://fhir.healthintersections.com.au/open/Patient/100 – fhir.orionhealth.com/blaze/fhir/Patient – https://his-medicomp-gateway.orionhealth.com/blaze/fhir/metadata • Tools – XML Editor (Oxygen) – REST Client (POSTMan) 21 Script • Search patient on name • GET single patient from list • XML & JSON • Update and PUT back • repeat REST Search • Show error
    22. 22. Page 22 • HL7 New Zealand When to use REST? • Want low coupling between systems – In theory, very little up-front negotiation required • Small, light-weight exchanges • Focus is CRUD operations – Also for publish/subscribe • Client-driven client-server orchestration • Server endpoint has fixed location • Well-suited for Mobile, PHR, Registries 22 Rest
    23. 23. Page 23 • HL7 New Zealand When to avoid REST? • Complex or server-driven orchestration – Order of operations matters (e.g. complex decision support) • Unit of work != resource – “Transaction” may be an option • Lack of trust in the client for audit, etc. 23 Rest
    24. 24. Paradigms: Documents
    25. 25. Page 25 • HL7 New Zealand Documents • Similar to CDA • Collection of resources bound together – Root is a “Composition” resource – Just like CDA header • Sent as an ATOM feed – Usually stored as binary blob – Can be separate resource with Composition as ‘entry’ point • One context – Not propagated • Can be signed, authenticated, etc. • Working on conversion between FHIR Doc & CDA 25 Documents
    26. 26. Page 26 • HL7 New Zealand Documents – are bundles 26 Observation Resource Composition Resource Section Section Device Resource Patient Resource Prescription Resource <feed> <entry> <Composition /> </entry> <entry> <Observation /> </entry> <entry> <Device /> </entry> <entry> <Prescription /> </entry> <entry> <Patient /> </entry> </feed> AttesterMetadata
    27. 27. Page 27 • HL7 New Zealand The Composition resource 27
    28. 28. Page 28 • HL7 New Zealand Document Management • The DocumentReference resource – Enables ‘XDS-like’ services • The ‘registry’ is just a FHIR server – Same query capabilities • Point to document – Any document (FHIR Doc, CDA, PDF etc).
    29. 29. Page 30 • HL7 New Zealand XDS FHIR Style (MDS)
    30. 30. Page 31 • HL7 New Zealand When to use Documents? • No different to CDA • Focus is on persistence • No workflow involved – other than post/retrieve document • Need tight rules over authenticated content • Want to communicate multiple resources with control over how data is presented • Data spans multiple resources 31 Documents
    31. 31. Page 32 • HL7 New Zealand When to avoid Documents? • Need for workflow – Request/response, decision support • Data is dynamic – I.e. want view of data now, not at time of authorship – Multiple contributors over time • Resources need to be accessed/manipulated independently 32 Documents
    32. 32. Paradigms: Messages
    33. 33. Page 34 • HL7 New Zealand Messages • Similar to v2 and v3 messaging • Also a collection of resources as an ATOM feed • Allows request/response behavior with bundles for both request and response – /message endpoint on REST server • Event-driven – E.g. Send lab order, get back result • Can be asynchronous 34 Messages
    34. 34. Page 35 • HL7 New Zealand Messages – are bundles 35 Observation Resource MessageHeader source destination Device Resource Patient Resource <feed> <entry> <MessageHeader /> </entry> <entry> <Observation /> </entry> <entry> <Patient /> </entry> <entry> <Device /> </entry> </feed> event
    35. 35. Page 36 • HL7 New Zealand MessageHeader Resource 36 Resource used in both request & response
    36. 36. Page 37 • HL7 New Zealand FHIR messages • No storage of the “Message” resource implied. Might be used in a router, converted to v2, etc. • The server can process them based on the event code and return the response as another message (again a bundle). 37
    37. 37. Page 38 • HL7 New Zealand Communicating messages • Message Exchange Pattern • Synchronous in standard • Async supported • Reliability • Transport • REST supported but, you can send FHIR Messages over mail, MLLP, TCP, IPoAC (or Healthlink!) • FHIR defines an HTTP end-point for messages • http://server.org/fhir/Mailbox • Response comes back in the acknowledgment payload 38
    38. 38. Page 39 • HL7 New Zealand Revisiting the Immunization Forecast TCH ForecasterFHIR ServerFHIR Client TCH Forecaster with FHIR Message InterfaceFHIR Client
    39. 39. Page 40 • HL7 New Zealand When to use Messaging? • Request/response workflow • Need to drive behaviors more complex than CRUD on a single resource – E.g. merge, complex queries • Need for asynchronous communications • Need to communicate information about many resources but want to minimize exchanges • No “identity” for many resources 40 Messages
    40. 40. Page 41 • HL7 New Zealand When to avoid Messaging? • Precise control required on how data gets persisted/displayed to humans • Need for lightweight communications • Want to avoid pre-negotiations on behavior 41 Messages
    41. 41. Paradigms: Services
    42. 42. Page 43 • HL7 New Zealand Service Oriented Architecture (SOA) • Do whatever you like – (based on SOA principles) – Ultra complex workflows – Ultra simple workflows – Individual resources or collections (in Atom or other formats) – Use HTTP or use something else – Only constraint is that you’re passing around FHIR resources in some shape or manner 43 Services
    43. 43. Page 44 • HL7 New Zealand When to use Services? • All previous paradigms are a type of services interface • Use a custom service when capabilities of other paradigms don’t fit requirement – Operations other than CRUD on a resource (e.g. decision support) – Workflow more complex than simple request/response – Need to mix document persistence with behavior 44 Services
    44. 44. Page 45 • HL7 New Zealand When not to use services? • When something else will do the job as well – I.e. Don’t define a custom service for something that already naturally is handled by REST, messaging, etc. 45 Services
    45. 45. Page 46 • HL7 New Zealand Paradigm guidance • No absolutes – Consider a “when to avoid” as a note of caution – Capabilities/architecture of legacy will often drive approach, particularly initially • E.g. If v2 back end, messaging – Architectures will be driven by legacy requirements, architectural preferences, enterprise architecture commitments, etc. 46
    46. 46. Page 47 • HL7 New Zealand Combining paradigms • No requirement for a system to only support one paradigm – E.g. hospital may be primarily messaging, but use documents for discharge summaries and reports and expose registries and appointments via REST with a few custom services for decision support or specialized workflow • Data (generally) shared easily across paradigm boundaries • Caveats: – If updates come in via document, message or service, RESTful version id still needs to increment – Documents should typically be persisted whole, not reconstituted from parts • Ensures signature validity – Legacy messaging systems may not provide the metadata to easily expose or manipulate discrete resources via REST 47
    47. 47. Resources in more detail
    48. 48. Page 49 • HL7 New Zealand Resource Definition • Every resource definition has: – Scope and use – ‘UML’ representtaion – XML representation – Bindings – Constraints – Resource specific notes – Examples • And computable – XSD Schema – schematron
    49. 49. Page 50 • HL7 New Zealand XML & JSON <Patient xmlns="http://hl7.org/fhir"> <text> <status value="generated" /> <div xmlns="http://www.w3.org/1999/xhtml">Doe, John</div> </text> <identifier> <label value="NI" /> <system value="http://moh.govt.nz/fhir/patient/nhi" /> <value value="PRP1660" /> </identifier> <name> <use value="official" /> <family value="Garrett" /> <given value="Gordon" /> </name> </Patient> { "resourceType": "Patient", "text": { "status": "generated", "div": "<div xmlns="http://www.w3.org/1999/xhtml">Doe, John</div>" }, "identifier": [ { "label": "NI", "system": "http://moh.govt.nz/fhir/patient/nhi", "value": "PRP1660" } ], "name": [ { "use": "official", "family": [ "Garrett" ], "given": [ "Gordon" ] } ] }
    50. 50. Page 51 • HL7 New Zealand Specify format using REST GET /fhir/Patient/1?_format=json HTTP/1.1 HTTP/1.1 200 OK Content-Type: application/json+fhir;charset=utf-8 Content-Length: 787 GET /fhir/Patient/1 HTTP/1.1 Accept: application/json+fhir HTTP/1.1 200 OK Content-Type: application/json+fhir;charset=utf-8 Content-Length: 787 Same for Create/Update
    51. 51. Page 52 • HL7 New Zealand Resource metadata Patient MRN 22234 “Ewout Kramer” 30-11-1972 Amsterdam Metadata Resource Identities http://fhir.hl7.org/Patient/23E455A3B http://fhir.hl7.org/Patient/23E455A3B/_his Last updated 2013-12-23T23:33:01+01:00 http://hl7.org/fhir/tag/profile http://hl7.org/fhir/Profile/us-core http://hl7.org/fhir/tag http://example.org/fhir/Status#Test
    52. 52. Page 54 • HL7 New Zealand Identity • 2 different ‘sorts’ of identity – ID identifies a resource on a server • Is metadata • Will change between servers – Identifier • Business identifier • Is an element in the resource
    53. 53. Page 55 • HL7 New Zealand A Resource’s ID • In fact: an URL – http://server.org/fhir/Patient/1 endpoint resource type identifier Note: This URL resolves to the current version of a resource It’s also specific to a server
    54. 54. Page 56 • HL7 New Zealand “Business” identifiers
    55. 55. Page 58 • HL7 New Zealand Narrative
    56. 56. Page 59 • HL7 New Zealand Tags • Contain metadata about resources – Beyond ID, version & date • Used for different purposes: – Compliance to Profile – Security – e.g. sensitivity of resource – Indicate Document/Message – User defined • Transported in different ways: – REST – as an HTTP header – In a bundle (document, message, transaction) - in the feed.category element
    57. 57. Page 60 • HL7 New Zealand Versioning • Most recent version – http://server.org/fhir/Patient/1 – Returns single resource • All versions – http://server.org/fhir/Patient/1/_history – Returns bundle of versions • Specific version – http://server.org/fhir/Patient/1/_history/_1 – Returns single resource • Version support is optional • Works at instance and type level
    58. 58. Page 61 • HL7 New Zealand Resource Reference Example: part of DiagnosticReport
    59. 59. Page 62 • HL7 New Zealand Coded values: the ValueSet resource • Most coded elements have a set of possible values – Large or small – Static • (change slowly) • Can use ValueSet resource to define set of possibilities – A “true” FHIR ValueSet resource (may be version specific) • Can contain: – References to a terminology (like SNOMED) – A list of specific codes • Examples – International examples • All the HL7 version 2 ‘tables’ – NZ Examples • Iwi & Hapu • DHB’s 62
    60. 60. Page 63 • HL7 New Zealand Example of ValueSet <?xml version="1.0" encoding="UTF-8"?> <ValueSet xmlns="http://hl7.org/fhir"> <text> <status value="additional"/> <div xmlns="http://www.w3.org/1999/xhtml">The value set for confidentiality codes in the elbonian docume project. The codes are defined directly by the valueset, rather than references to an external terminology</d </text> <name value="ConfidentialityOptions"/> <description value="ConfidentialityOptions"/> <status value="draft"/> <!-- Define the options in the resource rather than an external terminology--> <define> <system value="http://fhir.moh.elbonia.com/confidentiality"/> <concept> <code value='N'/> <display value="Normal"/> <definition value="That the document is of normal confidentiality "/> </concept> <concept> <code value='H'/> <display value="High"/> <definition value=”That the document is Highly confidential - eg Mental health "/> </concept> </define> </ValueSet>
    61. 61. Page 64 • HL7 New Zealand Contained resources • When the contained resource has no separate identity • Has quite a few limitations • Use sparingly – Bundle always better if possible <Composition xmlns="http://hl7.org/fhir"> <extension>...</extension> <text>...</text> <contained> <Organization id="org1"> <!– other data --> </Organization> </contained> <information> <!-- other attributes --> <custodian> <reference value="#org1" /> </custodian> <!-- other attributes --> <information> </Document>
    62. 62. Bundles in more detail
    63. 63. Page 66 • HL7 New Zealand Review • Atom as the bundling mechanism – Query results – Document – Message • Request & Response – Batch/Transactions • XML or JSON – Conversion routines available – (Can’t use ordinary ones) • Use tags to identify Documents & Messages – First resource significant
    64. 64. Page 67 • HL7 New Zealand
    65. 65. Page 68 • HL7 New Zealand Resource Entry Version-specific id Resource id Last modified Resource content Human-readable form, just like Resource.text Tags
    66. 66. Page 69 • HL7 New Zealand Bundle as a serialized Object Graph
    67. 67. Profiles and Extensions:Profiles
    68. 68. Page 71 • HL7 New Zealand The need for Profiles • Many different contexts in healthcare, but a single set of Resources – A desire to keep the resources manageable – Most elements in base resources optional • Need to be able to: – Describe restrictions based on use and context – Support elements not in the core resource • Allow for these usage statements to: – Authored in a structured manner – Published in a repository – Discoverable at Design and Run-time – Used as the basis for validation, code, report and UI generation. 71
    69. 69. Page 72 • HL7 New Zealand Profiling a resource. For example... 72 Require that the identifier uses the NHI – and is required Limit names to just 1 (instead of 0..*) Limit maritalStatus to another set of codes that extends the one from HL7 international Add an extension to support “Iwi” Note: hardly any mandatory elements in the
    70. 70. Page 73 • HL7 New Zealand Capabilities of Profiles • Descriptive – Information about the Profile (what, why, who) • Extending a resource – Adding new elements – Same capabilities/datatypes as existing ones • Constraining a resource – Specifying datatypes for an element – Modifying datatypes (eg translations) – Defining terminology bindings – Specifying multiplicity (eg make an element required) – Further refining repeating values (‘Slicing’) • Example of Composition.section (Document) – Cannot specify default values for resource instances • Everything explicit in an instance
    71. 71. Page 74 • HL7 New Zealand Structured & published • A Profile is just a “normal” Resource • Any FHIR server could serve Profiles (just like Patients, Observations, etc…) • So, any FHIR server is a profile repository! • A profile is simply referred to by its URI: – Like any other resource • e.g. http://hl7.org/fhir/Profile/iso-21090 – Extensions in an ‘instance’ of a resource refer to the profile that defined them using the URI – Need to think about re-usability when designing profiles 74
    72. 72. Page 75 • HL7 New Zealand Who publishes a Profile? http://www.hl7.org/fhir/Profile/iso -21090 http://www.hl7org.nz/fhir/Profile/ patient http://www.health4all.org/fhir/Pro file/
    73. 73. Page 76 • HL7 New Zealand Using profiles • If we are a server then a client can read our conformance resource, which will list the profiles we support, and provide a link to them. – Conformance also has other functions like specifying supported resources, operations on those resources & interoperability paradigms • If we are a client, we can tell a server that we conform to a profile using a tag (the server will probably still check). – We could also ask a server just to validate – Could set up ‘distributed’ validation with (eg) National Validation servers used by local/regional servers • If we receive a resource with an extension we don’t recognize, it will point to the profile in which it is described so we can decide what to do with it. – Note that a single resource can reference different profiles 76
    74. 74. Page 77 • HL7 New Zealand What’s in a profile, and its relationships? 77 Descriptive Identifier Name, Version Publisher Description, Code Status Date (of publication) Resource and Datatype Constraints Extension Definition Conformance (server) Resource (via Tag) ValueSet ValueSet Extension in Resource Tag
    75. 75. Page 78 • HL7 New Zealand Scale / design • Make a profile with just extensions • Make a profile with just 1 resource + extensions on that resource • Make a profile with all (say national) resources + extensions. 78
    76. 76. Page 79 • HL7 New Zealand Profile Descriptive information • To describe the purpose of the Profile • To help with location • Details – Identifier: Universally unique identifier, assigned by author value=“urn:hl7.org:extensions:iso-21090“ or “2.16.840.1.113883.” – Version: Version of the profile, manually maintained by author. Suggested format: a timestamp (e.g. 2013-01-01T12:34:45) – Name: Free natural text name (e.g. “Extensions to support Orion Medications”) – Publisher: organization or individual responsible for publishing. Should be populated (e.g. “FHIR Project Team“) – Telecom: one or more contact points of the publisher (telephone, email, website etc) – Description: longer description of the contents of the profile – Code: one or more coded descriptions to help with finding the profile – Status (fixed choice of draft, active, retired) + experimental Y/N – Requirements: scope & usage (the “need” or “why” of the profile) – Date (of publication), e.g. “2013-07-07" 79
    77. 77. Page 80 • HL7 New Zealand Constraining Structures (elements) • Defining terminology bindings – ValueSet is useful • Specify element datatypes • Further refining repeating values (‘Slicing’) • Specifying multiplicity From the spec Possibilities
    78. 78. Page 81 • HL7 New Zealand Profile example Medication.code with a defined valueset
    79. 79. Page 82 • HL7 New Zealand Profile Example • MedicationPrescription.asNeeded required, and must be boolean
    80. 80. Page 83 • HL7 New Zealand Slicing • Constraining an element with 0..* , 1..* • FHIR Document as an example • Composition resource is the CDA Header equivalent – Composition.section is 0..* – A CCDA equivalent profile might specify the sections allowed • Different document types would have a profile
    81. 81. Profiles and Extensions: Extensions
    82. 82. Page 85 • HL7 New Zealand Extensions • Resources design for the 80% - Allow easy extension for the remaining 20% of elements • Note - You’re not extending a resource per se, but you specify its characteristics and where an extension may occur: – A specific element within a resource – A specific element within a datatype – All elements referencing a datatype – All elements mapping to a specific mapping target – An extension
    83. 83. Page 86 • HL7 New Zealand Extensions • In FHIR, extensions are “normal” – Consequence of the 80% rule – keep the simple stuff simple – Extensions can exist anywhere • Yes, even inside boolean or date – Conformant systems can’t reject instances just because they contain unrecognized extensions – They could: • Display them – Should be in resource narrative • Store as a ‘Blob’ • Make a conscious decision to ignore (unless ModifierExtension) – (Could lookup profile) 86
    84. 84. Page 87 • HL7 New Zealand Extension definition 87 Note: multiple contexts!
    85. 85. Page 88 • HL7 New Zealand An Extension in a resource 88
    86. 86. Page 89 • HL7 New Zealand Extending a multiple birth Key = location of formal definit Value = value according to definition
    87. 87. Page 90 • HL7 New Zealand Modifier Extensions • Also a core part of FHIR – Needed because some extensions can’t be safely ignored – Can’t compute on an element containing an unrecognized modifier extension. However, can: • Reject instance • Just display narrative • Retrieve definition & seek human review 90
    88. 88. Page 91 • HL7 New Zealand Modifier Extension decisions • When should you introduce them? – modifierExtension breaks interoperability so: • If you can accomplish your objective without one, do that – Consider a new resource or Other – Could requirement be met by an element that doesn’t change other element interpretations? – Best used when already part of existing practice, but in too narrow an area to justify being part of core 91
    89. 89. Page 92 • HL7 New Zealand ‘Other’ resource • When there’s no way to extend an existing one • Has: – Identifier – Code – Subject – Author – Created • Rest is extensions • Should discuss with community first
    90. 90. Page 93 • HL7 New Zealand Designing a Profile • Define Use Case • Choose resources – ‘Other’ if you have to • Constrain base elements – Remove – Make required – Define ValueSets and bindings • Define extensions – Try to re-use existing if possible – Note ‘hierarchy’ of extensions: • HL7 • National • Local • Build profile • Publish
    91. 91. Page 94 • HL7 New Zealand The need for Governance • Profiles & extensions allow a user to customize their use of FHIR • HL7 is establishing publically available registries – For reference purposes • With great power...
    92. 92. Page 95 • HL7 New Zealand Profile editors • Forge (FHIR.furore.com/forge)
    93. 93. Server specific notes
    94. 94. Page 97 • HL7 New Zealand Overview of a server 97 HTTP / REST interface Encoding/decoding, param validation, syntax validation Fhir Service Indexer / Search Storage Implement service operations as described in spec
    95. 95. Page 98 • HL7 New Zealand From wire to store Storage Fhir Service REST interface JSON/XML POCO/POJ O DBMS O-R Map FHIR Parser 98 JSON/XML POCO/POJ O Serialize FHIR Parser NoSql (Xml/Json) JSON/XML POCO/POJ O DBMS Serialize FHIR Parser
    96. 96. Page 99 • HL7 New Zealand Conformance resource • Allows a server to indicate: – Metadata about the server – The resources they support • The queries against those resources – The paradigms they support • REST, messaging, services – Specific (custom) queries – The profiles it supports • Is a normal resource – Supports discoverability (think UDDI for SOAP)
    97. 97. Page 100 • HL7 New Zealand Conformance • Which FHIR version? • Which resources? • Which paradigms ? • What search operations? • What formats? • What profiles? • Is this a test server? • Who can I contact? • Do you support History? • Do you support JSON/XML? • Is a normal resource • Supports discoverability (think UDDI for SOAP)
    98. 98. Page 101 • HL7 New Zealand Operation Outcome • When something goes wrong….return the OperationOutcome Resource!
    99. 99. Page 102 • HL7 New Zealand Special endpoints • Binary – Store/retrieve a blob. – No query • Document – Works at ‘document’ level – Query on composition • Mailbox – Processing endpoint – Exact actions depending on Trading Partner Agreement • Note MessageHeader properties – eg event, reason
    100. 100. Workflow
    101. 101. Page 104 • HL7 New Zealand Workflow • Resource describe ‘things’ • Workflow says what to do with those things • Eg – ePresciption – Lab order – Referral • Order resources – Order – OrderResponse • Combination of Order(for workflow) and specific resource – Eg Order + MedicationPrescription
    102. 102. Page 105 • HL7 New Zealand Referrals workflow 105
    103. 103. Security and Privacy (Coming to the end…)
    104. 104. Page 107 • HL7 New Zealand Overview • Signatures – On bundles • Tags used to ‘annotate’ resources – Eg private resource, ‘Special Patient’ – Application applies policy • Resources are atomic level • Some ‘security-related’ resources – SecurityEvent – Provenance • Philosophically FHIR delegates security to infrastructure – Others do that better – But does have comments
    105. 105. Page 108 • HL7 New Zealand Wrapping Up: Tools for Developers • Specification – The full specification (included build tools) can be downloaded from the CVS at: http://gforge.hl7.org/gf/project/fhir • (Free to download, need account to update) • Examples • Validation files – XSD, Schematron • Test Servers – Open source • Reference Implementations – Java, .net, Objective-C, javascript – Open source – Reference Implementations from www.hl7.org/fhir • Tooling – XML/JSON editor – REST client 108
    106. 106. Page 109 • HL7 New Zealand Further Information & Help • Information: – Specification: www.hl7.org/fhir • Fully hyper-linked • Includes many sample files and links to codesets & terminologies – Wiki pages: http://wiki.hl7.org/index.php?title=FHIR – HL7 Lists server: from HL7.org – Blogs (listed on spec) • Assistance – ‘Stack Overflow’ – tag hl7-FHIR – Skpe conversations (email me – david.hay@orionhealth.com to be included)
    107. 107. Whew! Next Steps in New Zealand? A group discussion