HL7 Centralized Terminology Services (CTS)

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HL7 Centralized Terminology Services (CTS)

• Harold Solbrig
• Mayo Clinic
• May 25, 2000

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Centralized Terminology Services

• What are the issues that a terminology service
  group might be charged with resolving?
• What approach should be taken toward arriving at
  a resolution?

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CTS What are (some of) the issues?

• CE Domain definitions may not always be obvious.
  How do I, ABC Clinical Systems, write software to
  implement the following?

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CTS What are (some of) the issues?

• (2) CE messages dont necessarily (and, in fact,
  probably shouldnt) carry all of the information
  about a given code

Patient Blood Type Code Value ( value
F-D1111, code-system SMI -- from a table ) .
What is the patients blood type?
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CTS What are (some of) the issues?

• (3) Valid values for some domains may not be
  fully specified and/or may undergo frequent
  revision.

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CTS What are (some of) the issues?

• (4) Mapping between local coding system and
  standard coding system may be non-trivial.

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CTS What are (some of) the issues?

• (5) Template assembly and validation may require
  inferential capabilities (e.g. Is HGB a numeric
  lab test? What are the possible value codes for
  a blood group, etc.)

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CTS What are (some of) the issues?

• Many more
• Coding schemes (systems of codes) can be
• Dynamic
• Compositional
• Embody complex structures
• Have rich representational structures

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Centralized Terminology Services

• Emphasis is on Services. Centralized is a bit
  misleading, as the specification should not
  presume a particular architecture.
• View centralized as implying functionally
  opaque a body of software that performs
  specified tasks without the user necessarily
  understanding how the tasks are performed.

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Proposed Approach

• Define and describe the set of tasks that the
  services need to accomplish.
• Develop a technology neutral specification ala
  CCOWs CMA
• Develop a set of technology specific specific
  component mapping specifications
• Develop a set of technology specific UI
  specifications (if necessary)

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Technology Neutrality

• See section3 of the CMA document
• Candidate technologies include
• Inter-component communication via Microsoft
  Automation through COM/DCOM via any CORBA 2.0
  compliant object request broker via SOAP
  (when/if adopted by W3C)
• Programming languages any language that can be
  interfaced with Microsoft Automation and/or CORBA
  (e.g., VisualBasic, C, Java, MUMPS).
• Operating Systems Windows 95 Windows NT any
  platform that can host a Java virtual machine.

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CTS Process
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What about SOAP?

• Simple Object Access Protocol
• XML based
• http//www.w3.org/TR/SOAP/
• Another candidate in the transform set including
• UML
• OMG IDL
• MIDL
• RMI
• EJB

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Technologies

• UML

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Technologies

• CORBA
• module CentralTerminologyServices
• typedef string ConceptCode
• typedef string Representation
• interface LexExplorer
• Representation get_preferred_text (
• in ConceptCode concept_code
• )

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Technologies

• COM/DCOM
• interface ICentralTerminologyServices_LexExplorer
  
• typedef string char CentralTerminologySer
  vices_ConceptCode
• typedef string char CentralTerminologySer
  vices_Representation
• object,
• uuid(20CAE216-2895-1A51-1D7F-5FB687A59E54)
  ,
• pointer_default(unique),
• helpstring("CentralTerminologyServicesLe
  xExplorer")
• interface ICentralTerminologyServices_LexExplo
  rer IUnknown
• HRESULT get_preferred_text(in
  CentralTerminologyServices_ConceptCode
  concept_code,
• out
  CentralTerminologyServices_Representation val)

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Technologies

• SOAP
• ltidlgt
• ltmodule name"CentralTerminologyServices"gt
• lttypedef name"ConceptCode" repositoryID"IDLCe
  ntralTerminologyServices/ConceptCode1.0"
  type"string"/gt
• lttypedef name"Representation"
  repositoryID"IDLCentralTerminologyServices/Repre
  sentation1.0" type"string"/gt
• ltinterface name"LexExplorer"
  repositoryID"IDLCentralTerminologyServices/LexEx
  plorer1.0"gt
• ltoperation name"get_preferred_text"gt
• ltreturn type"Representation"/gt
• ltparametersgt
• ltparameter type"ConceptCode"
  name"concept_code" dir"in"/gt
• lt/parametersgt
• lt/operationgt
• lt/interfacegt
• lt/modulegt
• lt/idlgt

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Technologies

• CMA-IDL
• interface LexExplorer
• get_preferred_text
• inputs(string concept_code)
• outputs(string preferred_text)
• Note manual translation unsure of availability
  of
• CMA-IDL lt-gt IDL/JAVA/UML/MIDL/ tools

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Proposed Next Step

• Scope statement
• Solicit requirements from HL7 members at large
• Do they need a CTS?
• If so, how do they anticipate it being used
  within their architectures.