VistA Architecture and Semantic Web Futures

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VistA Architecture and Semantic Web Futures
By David Whitten, Rick Marshall
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• The software architecture of a program or
  computing system is the structure or structures
  of the system, which comprise software elements,
  the externally visible properties of those
  elements, and the relationships between them.
• From the book Software Architecture in Practice
  (2nd edition),
• (Bass, Clements, Kazman Addison-Wesley 2003

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• Software architecture is a coherent set of
  abstract patterns, or principles, guiding the
  design of each aspect of a large software
  system. - Wahab Ahmed (Software Engineer,
  National, Islamabad, Federal, Pakistan)
• "Software architecture is the set of design
  decisions which, if made incorrectly, may cause
  your project to be cancelled." - Eoin Woods,
  software architect

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Why say Software has an Architecture?

• Every system (software, hardware, or
  organizational) can be shown to be composed of
  elements and relations among them.
• The Architecture is the structure between those
  elements beyond the relationships.

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Why this Talk?

• Even though every system has an architecture, it
  does not necessarily follow that the architecture
  is known to anyone.
• An architecture can exist independently of its
  description or specification
• Discussion of architecture increases
  understanding of design decisions and helps avoid
  implementing contradictions

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What are the elements of VistA Architecture?

• CPRS
• CPRS is one of the externally visible properties
  of the software elements
• Text Interface
• Roll and Scroll, ListMan, ScreenMan are
  also externally visible properties of the
  software elements
• M2Web or ESI-Objects or Java Front Ends (for the
  same reasons)

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What are the elements of VistA Architecture?

• FileMan fields or Files
• They are the structural elements that provide
  relationships
• MUMPS code and globals
• They are the stuff from which all the VistA
  Archictecture elements are molded from.
• Host Operating System and Host File System, and
  Network (Internet Intranet) (again, low level
  structures and services )

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What are the elements of VistA Architecture?

• For Client Server Applications (like CPRS)
• REMOTE PROCEDURE FILE
• Defines services available from the VistA server
• RPC Broker or VistALink or HL7
• Defines communication protocol for a client
  program to request services, to supply
  information and receive results
• BROKER type options in OPTION File
• Define accessibility of particular RPCs to client

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What are the elements of VistA Architecture?

• PROTOCOL File
• Defines Object Oriented, Message-passing
  relationships between VistA elements
• Defines High Level Events
• Name change for Patients
• Patient Movement within the Institution
• HL7 Messages received
• Links Subcribers and Publishers

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What are the elements of VistA Architecture?

• The OPTION File
• Defines encapsulated things that a user may
  want to do
• Differentiated by TYPE
• Print Options defining output
• Input/Screen Options defining inputs
• Menu/Broker Options collections of other
  things
• Server Options defining Mail message processors
• Run/Action Options link to MUMPS code

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What are the elements of VistA Architecture?
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What are the elements of VistA Architecture?

• TIU Document Type defines a hierarchy of text
  documents
• PARAMETERS File defines a hierarchy of software
  switches based on user, hospital location,
  division, software package, etc.
• LEXICON provides a hierarchy of Medical terms
  covering vast aspects of recording medical care
  issues.

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What is the Semantic Web?

• An evolving extension of the World Wide Web
• Web content can be expressed in natural language
  (ie English, Russian, Chinese)
• Web content can be read and used by software
  agents
• permitting them to find information
• share information
• integrate information more easily.

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• The Semantic Web allows data itself to become
  part of the World Wide Web
• The Semantic Web defines relationships between
  data using technologies like RDF, CycL and XML.
• The Semantic Web defines processes and services
  which can be provided independently of the
  original application, computing platform or
  software architecture

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an ontology is a specification of a
conceptualization-- Tom Gruber
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• An ontology is more than a controlled vocabulary
  with hierarchical organization.
• The LEXICON in VistA provides ways of naming
  medical processes and products
• LOINC standardizes laboratory tests
• The Pharmacy National Drug File (PSNDF)
  standardizes generic drug names, interactions.

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Thank you

• David Whitten
• Chief Technology Officer
• WorldVistA
• 713-870-3834
• Rick Marshall
• Executive Director
• VISTA Expertise Network
• 206-632-0166