Difference between revisions of "Transport Pattern Mapping"
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There are some exceptions to this scheme: the "transaction" operation utilizes POST to create or update a set of resources (resource bundle) atomically. | There are some exceptions to this scheme: the "transaction" operation utilizes POST to create or update a set of resources (resource bundle) atomically. | ||
+ | |||
+ | == HTTP headers == | ||
+ | As with most REST based APIs, Content-Type and Accept headers are used to process or request a specific representation of a resource. | ||
== Mapping of FHIR operations to existing IHE transactions == | == Mapping of FHIR operations to existing IHE transactions == | ||
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== Resources == | == Resources == | ||
− | Resources in FHIR can be represented in JSON, XML and as Binary. Binary content can be specified using the "content" | + | Resources in FHIR can be represented in JSON, XML (application/xml+fhir) and as Binary. Binary content can be specified in JSON using the "data" attribute on "content" objects, containing Base64 encoded data. XHTML content can be conveyed through a "div" attribute on "text" objects. For the XML representation, these are both XML elements. In JSON, the "resourceType" attribute specifies the type of resource (Bundle, Patient,...). |
=== Binary === | === Binary === | ||
− | Binary representations can be created, and fetched using a specific location on the resource. Search is not supported for such a resource. | + | Binary representations can be created, and fetched using a specific location on the resource. Search is not supported for such a resource. The mime type matches the binary content. |
=== Bundles === | === Bundles === | ||
− | Operations on sets of resources are performed on resource bundles. In XML these are represented as Atom Feeds (RFC 6721). The JSON representation is a custom format that honors logical order in entries. | + | Operations on sets of resources are performed on resource bundles. In XML these bundles are represented as Atom Feeds (RFC 6721) (mime type: application/atom+xml). The JSON representation (mime type: application/json+fhir; "resourceType": "Bundle") is a custom format that honors logical order in entries, and tries to follow the XML representation where possible. |
Revision as of 08:07, 18 July 2014
FHIR-MHD Transport Pattern Mapping Notes
- FHIR REST API (in least in theory) is based on OMG Health RESTful specification
- http://www.omg.org/spec/HData/1.0/PDF/
- on first inspection, it does not seem to cause incompatibility issues with existing use of REST in MHD.
- the recommendation of using CORS has impact on HTTP level: http://enable-cors.org/. Discussed in http://www.hl7.org/implement/standards/fhir/security.html
HTTP verbs used for basic operations on a (single) resource in FHIR
- POST - create
- PUT - update
- DELETE - delete
- GET - read
There are some exceptions to this scheme: the "transaction" operation utilizes POST to create or update a set of resources (resource bundle) atomically.
HTTP headers
As with most REST based APIs, Content-Type and Accept headers are used to process or request a specific representation of a resource.
Mapping of FHIR operations to existing IHE transactions
Transaction
This operation can facilitate Provide & Register Document Set-b (ITI-41, ITI-42), "Update Document Set" (ITI-57) and "Delete Document Set" (ITI-62) transactions. It can create and update a set of resources (authors, documents) in one transaction:
- If entry.content is omitted, the resulting operation maps to Register Document Set-b (ITI-42).
- If entry.id refers to an existing resource, it mimicks "Update Document Set" (ITI-57)
- If entry.deleted specifies a date before now, the entry will be deleted, mimicking "Delete Document Set" (ITI-62). Note that entry.content will also be deleted.
The MHD "Put Document Dossier" (ITI-65) transaction could be mapped in a similar fashion. This would enrich the semantics of this transaction and add support for the creation of multiple resources.
Read
This operation can be used for the current Retrieve Document Set (ITI-43) transaction, although it can only be used for a single resource. The "search" operation might be an alternative.
Delete
This operation can be mapped to Delete Document Set (ITI-62), but only works for a single resource.
Update
This operation can be mapped to Update Document Set (ITI-57), but only works for a single resource.
Resources
Resources in FHIR can be represented in JSON, XML (application/xml+fhir) and as Binary. Binary content can be specified in JSON using the "data" attribute on "content" objects, containing Base64 encoded data. XHTML content can be conveyed through a "div" attribute on "text" objects. For the XML representation, these are both XML elements. In JSON, the "resourceType" attribute specifies the type of resource (Bundle, Patient,...).
Binary
Binary representations can be created, and fetched using a specific location on the resource. Search is not supported for such a resource. The mime type matches the binary content.
Bundles
Operations on sets of resources are performed on resource bundles. In XML these bundles are represented as Atom Feeds (RFC 6721) (mime type: application/atom+xml). The JSON representation (mime type: application/json+fhir; "resourceType": "Bundle") is a custom format that honors logical order in entries, and tries to follow the XML representation where possible.