Knowledge base


What is HL7® Messaging?

HL7® Version 3 like Version 2.x is a standard developed for exchanging information in form of messages among information systems that implement health care applications. Version 3 is an answer to strong need to improve old process to handle the breadth and complexity of messaging. The new process results in more rigorous specification.

The main drawbacks of Version 2.x are:

  • development process is entirely ad hoc,
  • no explicit methodology,
  • no formal guidance in constructing messages,
  • natural language description for data fields and trigger events,
  • unclear structural relationship between data fields,
  • segments reused in many messages,
  • message definition reused in many trigger events,
  • demand for extensive reuse make most of data fields optional,
  • inconsistency in usage of trigger events versus status codes,
  • no specification for specific kind of healthcare information system.

Version 3 principles:

  • internalization – support for local variants of messages,
  • version 2.x functional compatibility,
  • upward compatibility among Version 3.x – a message structure that is modified in a newer version of the protocol must be acceptable to a system designed for the prior V3 release,
  • confidentiality of patient information,
  • authenticated authorization for service,
  • security and privacy,
  • non-repudiation and integrity.

The main new features of Version 3 are:

  • HL7 version 3 adopts an Object Oriented (OO) approach using Unified Modeling Language (UML) principles,
  • messaging  standard (in contrast to Version 2.x) is based on Referenced Information Model (RIM).
  • implemented in Extensible Markup Language (XML) – as a part of Version 3 deveplopment methodology,
  • reduced optionality
  • testable conformance to Version 3 standard.