Health Level 7

Diatom Enterprises was involved in the development process for Latvian National level e-Health system which was based on HL7 standard. We have developed an innovative and efficient approach to work with 3rd party external web services based on HL7 interfaces. Senior Software developers of our company got a good HL7 standard expertise and added strict built-in quality control based on heavy usage of Unit tests, Integration tests and Functional testing solutions (SoapUI products).

About HL7 Standard

Health Level Seven (HL7), is a non-profit organization involved in the development of international healthcare informatics interoperability standards. “HL7” also refers to some of the specific standards created by the organization (e.g., HL7 v2.x, v3.0, HL7 RIM); HL7 and its members provide a framework (and related standards) for the exchange, integration, sharing, and retrieval of electronic health information. The 2.x versions of the standards, which support clinical practice and the management, delivery, and evaluation of health services, are the most commonly used in the world.

HL7 standard


HL7 is an international community of healthcare subject matter experts and information scientists collaborating to create standards for the exchange, management and integration of electronic healthcare information.

HL7 standards

Most HL7 standards are not Open Standards, depending on the definition, since the current HL7 International IP Policy requires that an implementer or user be an organizational member of HL7, which requires an annual payment of a fee. The revenue model and business plan of HL7 is discussed in HL7 Strategic Initiatives and Implementation Proposal. However, since the earlier policy as described in the Bylaws of October 2002 placed the HL7 protocol specifications in the Public Domain, and under 17 USC § 102 there is no copyright protection for an “idea, procedure, process, system, method of operation, concept, principle, or discovery”, this revised policy may not be enforceable. In August 2012, the HL7 Board of Directors has announced its decision to relax this policy and allow free access and implementation to promote adoption and interoperability.

Hospitals and other healthcare provider organizations typically have many different computer systems used for everything from billing records to patient tracking. All of these systems should communicate with each other (or “interface”) when they receive new information but not all do so. HL7 specifies the number of flexible standards, guidelines, and methodologies by which various healthcare systems can communicate with each other. Such guidelines or data standards are a set of rules that allow information to be shared and processed in a uniform and consistent manner. These data standards are meant to allow healthcare organizations to easily share clinical information. Theoretically, this ability to exchange information should help to minimize the tendency for medical care to be geographically isolated and highly variable.

HL7 develops conceptual standards (e.g., HL7 RIM), document standards (e.g., HL7 CDA), application standards (e.g., HL7 CCOW), and messaging standards (e.g., HL7 v2.x and v3.0). Messaging standards are particularly important because they define how information is packaged and communicated from one party to another. Such standards set the language, structure and data types required for seamless integration from one system to another.

HL7 encompasses the complete life cycle of the standards specification including the development, adoption, market recognition, utilization, and adherence. HL7 International currently asserts that business use of the HL7 standards requires a paid organizational membership in HL7, Inc. HL7 Members can access standards for free, and non-members can buy the standards from HL7, ANSI, or for some standards, ISO.

The Reference Information Model (RIM) and the HL7 Development Framework (HDF) are the basis of the HL7 Version 3 standards development process. RIM is the representation of the HL7 clinical data (domains) and the life cycle of messages or groups of messages. HDF is a project to specify the processes and methodology used by all the HL7 committees for project initiation, requirements analysis, standard design, implementation, standard approval process, etc.

Clinical Document Architecture – ISO/HL7 27932

The HL7 Clinical Document Architecture (CDA) is an XML-based markup standard intended to specify the encoding, structure and semantics of clinical documents for exchange.

Methods applied by HL7

Services Aware Interoperability Framework

The HL7 Services-Aware Enterprise Architecture Framework (SAIF) provides consistency between all HL7 artifacts, and enables a standardized approach to Enterprise Architecture (EA) development and implementation, and a way to measure the consistency.

SAIF is a way of thinking about producing specifications that explicitly describe the governance, conformance, compliance, and behavioural semantics that are needed to achieve computable semantic working interoperability. The intended information transmission technology might use a messaging, document exchange, or services approach.

SAIF is the framework that is required to rationalize interoperability of other standards. SAIF is an architecture for achieving interoperability, but it is not a whole-solution design for enterprise architecture management.

Arden syntax

The Arden syntax is a language for encoding medical knowledge. HL7 adopted and oversees the standard beginning with Arden syntax 2.0. These Medical Logic Modules (MLMs) are used in the clinical setting as they can contain sufficient knowledge to make single medical decisions.[citation needed] They can produce alerts, diagnoses, and interpretations along with quality assurance function and administrative support. An MLM must run on a computer that meets the minimum system requirements and has the correct program installed. Then, the MLM can give advice for when and where it is needed.


A large portion of HL7 messaging is transported by Minimal Lower Layer Protocol (MLLP), also known as Lower Layer Protocol (LLP). For transmitting via TCP/IP, header and trailer characters are added to the message to identify the beginning and end of the message because TCP/IP is a continuous stream of bytes. Hybrid Lower Layer Protocol (HLLP) is a variation of MLLP that includes a checksum to help verify message integrity. Amongst other software vendors, MLLP is supported by Microsoft and Oracle.


CCOW, or “Clinical Context Object Workgroup,” is a standard protocol designed to enable disparate applications to share user context and the patient context in real-time, and at the user-interface level. CCOW implementations typically require a CCOW vault system to manage user security between applications.

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