Limitation of WADO

1
Limitation of WADO

• One SOP Instance only in one call (no way for
  retrieving all the series/study)
• Suited for Web Browser based solution, less for
  direct with applications
• The URL based query is easy to write, but not
  adapted for being parsed
• No easy way to help the application development
  through WSDL

2
Web Services why now?

• The WS are now maturing
• The deployment beyond web server to web server is
  emerging (application to appli.)
• The WS-I Profiles are defining a real
  interoperable solution, including (more or less!)
  the security and reliability aspects
• The MTOM mechanism for conveying binary content
  is now supported by development platforms (.Net,
  Java)

3
Web Services for Dummies

• Submitting a form to a Web Server, you are using
  http POST based structured message, containing
  the  input fields 
• It may also contain files to be uploaded
• WS are using such mechanism for the request and
  the response, and define the structure of message
  in XML SOAP
• A WSDL (XML) file defines the syntax of the
  communication (request and response)

4
MTOM for Dummies

• Date Thu, 09 Sep 2004 184752 GMT
• Server Apache/2.0.48 (Win32) mod_ssl/2.0.48
  OpenSSL/0.9.7d
• Keep-Alive timeout15, max100
• Connection Keep-Alive
• Transfer-Encoding chunked
• Content-Type Multipart/RelatedboundaryMIME_Boun
  darytypeapplication/xopxmlcharsetUTF-8start-
  info"application/soapxml"
• --MIME_Boundary
• Content-ID ltmymainpart_at_crf.canon.frgt
• Content-Type application/xopxmlcharsetUTF-8ty
  pe"application/soapxml"
• Content-Transfer-Encoding binary
• ltsoapEnvelope xmlnssoap"http//www.w3.org/2003/
  05/soap-envelope" xmlnsxmlmime"http//www.w3.org
  /2004/06/xmlmime" xmlnsxop"http//www.w3.org/200
  4/08/xop/include"gtltsoapHeadergtlt/soapHeadergtltsoa
  pBodygtltns1EchoTest xmlnsns1"http//example.org
  /mtom/data"gtltns1Data xmlmimecontentType"image/j
  peg"gtltxopInclude href"cidthismessage/resource
  0.jpeg"gtlt/xopIncludegtlt/ns1Datagtltns1Data
  xmlmimecontentType"image/jpeg"gtltxopInclude
  href"cidthismessage/resource1.jpeg"gtlt/xopInclu
  degtlt/ns1Datagtltns1Data xmlmimecontentType"image
  /jpeg"gtltxopInclude href"cidthismessage/resour
  ce2.jpeg"gtlt/xopIncludegtlt/ns1Datagtlt/ns1EchoTestgt
  lt/soapBodygtlt/soapEnvelopegt
• --MIME_Boundary
• Content-ID ltthismessage/resource0.jpeggt
• Content-Type image/jpeg
• Content-Transfer-Encoding binary
• ÿØÿàJFIF, (IMAGE 1 in BINARY)

5
WADO in WS, which form?

• IHE ITI wrote White Paper on WS implementation,
  based on WS-I
• The XDS.b Retrieve Document Set transaction is
  similar to WS/WADO
• All the WADO query parameters can be directly
  transposed  as is  in WS
• The response structure can be derived from the
  Retrieve Document Set structure

6
WADO  brothers 

• WADO implies to have the reference
• A notification mechanism may be developed on WS
  (NADO)
• A Query by IDs mechanism may enable an
  application to obtain the reference (QIDO)

7
NADO Notification of Availability of DICOM Objects

• WADO is supposing the Application retrieving the
  DICOM Object(s) is aware of it/their existence
  and availability. But no mechanism has been
  provided for informing the application that such
  DICOM Instance(s) are available.
• Similarly to the DICOM IAN (Instance Availability
  Notification), a WS based transaction may be
  defined for notifying the availability of DICOM
  Object(s). It addresses similar use cases than
  some targeted by the ISO TC215/WG2 WARM work
  item and it may correspond to an evolution of
  this one.
• The mechanism may imply a subscription by an
  application to be notified at different levels
  (study/series/instance) and the notification
  message may include, in addition to UIDS, at
  least the Patient Id, the Accession Number and
  the Modality.
• The Application may be implementing a WS server
  (so the DICOM system will act as a client to
  notify it) or as a WS client (so it has to query
  regularly or use the asynchronous mode of WS).

8
QIDO Query based on ID for DICOM Objects

• Similarly to the IHE ITI Retrieve Document for
  Display (RID) transaction, the Application can
  query the DICOM server to have a list of
  available DICOM objects.
• Parameters may be similar to those used for RID
  (Patient ID, date(s) and number of most recent)
  with the Accession Number (in addition to the
  Patient ID required for security reasons).
• The Application will act as a WS client, while
  the DICOM Server will act as a WS server.