1. Applying REST to DICOM Chris Hafey Feb 23, 2011

2. Introduction Three Types of Web Services – RPC Based (WS*) – REST – REST/RPC Hybrid Pure REST is a great fit for DICOM – Simple – Wide technology support – Many DICOM use cases are CRUDish

3. Resource Oriented Architecture Resources URIs Addressability Statelessness Representations Links and Connectedness Uniform Interface

4. Resources Entities – DICOM Modules Patient Study – UID Based Study, Series, Instance – Internals Image Frame Algorithms – Render Image – Search Complex Transactions – Merge Studies

5. URIs Entites – Use path to specify where an entity is – E.g – A study http://server/study/1.2.3.4.5 Algorithms – Use Path to specify which algorithm/entity to run – Pass algorithm parameters via http query parameters – E.g. – render a sop instance as a JPEG with a specific window center/window width http://server/study/1.2.3.4.5/series/1.2.3/instance/1.2.3?windowWidth=400&windowC enter=40 http://server/study/1.2.3.4.5/series/1.2.3/instance/1.2.3?windowWidth=400&windowC enter=40 Transactions – Use path to specify transactions – The transaction resource can point to other entities that will be affected

6. Addressability Expose interesting aspects of its data set as resources – Allows data to be used in ways not originally anticipated – E.g. exposing individual DICOM Modules to be independently accessed

7. Statelessness Each HTTP Request happens in complete isolation – No session – Simplifies error conditions – Can send the same web request multiple times without side effects

8. Representations Leverage MIME Types – Application/XML – Application/JSON – Application/DICOM – Image/JPEG – Image/PNG A resource can be returned in multiple representations

9. Links and Connectedness Use HREF to link between resources DICOM Examples – Patient to Study – Study to Series – Series to Instance – Presentation State to Image – Structured report to Image

10. Uniform Interface HTTP MethodPurposeRDBMS Analog GETRetrieveSelect PUTUpdate POSTCreateInsert DELETEDelete

11. Reference Books RESTful Web Services – Leonard Richardson & Sam Ruby RESTful Web Services Cookbook – Subbu Allamaraju REST in Practice – Ian Robinson, Jim Webber, and Savas Parastatidis