Health Level Seven (HL7) has announced the approval of a Web Services Profile and ebXML Message Service Specification 2.0 as Draft Standards for Trial Use (DSTUs) as Version 3 Transport Specifications within the HL7 Messaging Standard. The Web Services and ebXML transport specifications are two of over two dozen specifications that make up the HL7 Version 3 Messaging Standard.

The HL7 V3 project "represents a new approach to clinical information exchange. It is XML-based and built from the ground up around a single object model, the HL7 Reference Information Model (RIM) and a rigorous methodology that ties model to message and finally to syntax." A Version 3 HL7 Patient Administration Standard is also being published for a twelve-month period of trial use within the HL7 V3 project.

The HL7 Version 3 specification is "built around subject domains, for each of which it provides storyboard descriptions, trigger events, interaction designs, domain object models derived from the RIM, hierarchical message descriptors (HMDs) and a prose description of each element. Implementation of these domains further depends upon a non-normative V3 Guide and normative specifications for data types, the XML implementable technical specifications (ITS) or message wire format, message and control wrappers, and transport protocols."

The Web Services Profile for HL7 has been designed "in response to an industry need for increased interoperability between implementations; it focuses on basic Web services protocols and technologies like SOAP (Simple Object Access Protocol) and WSDL (Web Services Description Language), which lay the groundwork for more complex interactions based on higher-level Web services specifications."

The purpose of the HL7 ebXML transport specification is to "provide secure, flexible transport for exchanging HL7 messages between message handling interfaces or ebXML Message Service Handlers (ebXML MSH). It specifies an HL7-specific implementation of the ebXML Message Service specification, providing transport to move HL7 content, messages and documents over a variety of lower level transports, such as TCP/IP, HTML, and SMTP. This protocol optionally supports important features such as Duplicate Message handling, Reliable Messaging, Message Routing, Sequencing, and Digital Signatures. When using this protocol in combination with a certificate based TLS (Transport Layer Security) or SSL (Secure Sockets Layer) TCP/IP lower level transport it provides a robust, secure and authenticated communications infrastructure for exchanging HL7 V2 and V3 messages and content between organizations."

HL7 is a "not-for-profit, ANSI-accredited standards developing organization dedicated to providing a comprehensive framework and related standards for the exchange, integration, sharing, and retrieval of electronic health information that supports clinical practice and the management, delivery and evaluation of health services. HL7's more than 2,000 members represent over 500 corporate members, including 90 percent of the largest information systems vendors serving healthcare."

From the HL7 Announcements

The Web Services and ebXML DSTUs are both being published for a 24-month period of trial use, during which time users will provide to HL7 feedback on their experiences with the standards. This information will be helpful in shaping these standards into more effective documents for the healthcare industry. The documents will then be balloted at the membership level and, if passed, will be submitted to the American National Standards Institute (ANSI) for final approval as HL7 Standards.

Web Services is a way for applications to expose software services using standard interoperability protocols, regardless of the platform on which they are implemented. The development of interoperable standards and the focus on communication and collaboration among people and applications have created an environment where Web Services is becoming the protocol/technology of choice for application integration.

"We developed the Web Services Profile for HL7 in response to an industry need for increased interoperability between implementations and are very excited it achieved DSTU status in only one ballot cycle," says Roberto Ruggeri, editor of the standard and Technical Strategist, Microsoft Healthcare and Life Sciences. "This is the result of a tremendous collaborative effort, which will continue to evolve as we incorporate feedback from across the healthcare community."

There are many definitions of Web Service, but almost all definitions have these things in common:

• Web Services expose useful functionality to users through the Web Services protocols.

• Web services provide a way to describe their interfaces in enough detail to allow a user to build a client application to talk to them. This description is usually provided in an XML document called a Web Services Description Language (WSDL) document.

• Web services are registered so that potential users can find them easily. This is done with Universal Discovery Description and Integration (UDDI).

The Web Services Profile for HL7 promotes the use of Web Services to exchange HL7 messages and to ease interoperability between implementations. The profile focuses on basic Web services protocols and technologies like SOAP (Simple Object Access Protocol) and WSDL (Web Services Description Language), which lay the groundwork for more complex interactions based on higher-level Web services specifications.

ebXML is a specification for message communication in XML developed by the OASIS consortium (www.oasis-open.org). The purpose of the HL7 ebXML transport specification is to provide secure, flexible transport for exchanging HL7 messages between message handling interfaces or ebXML Message Service Handlers (ebXML MSH). It specifies an HL7-specific implementation of the ebXML Message Service as described in "Message Service Specification Version 2.0 1 April 2002". The transport will move HL7 content, messages and documents, as well as legacy standards over a variety of lower level transports, such as TCP/IP, HTML, and SMTP. This protocol optionally supports important features such as Duplicate Message handling, Reliable Messaging, Message Routing, Sequencing, and Digital Signatures. When using this protocol in combination with a certificate based TLS (Transport Layer Security) or SSL (Secure Sockets Layer) TCP/IP lower level transport it provides a robust, secure and authenticated communications infrastructure for exchanging HL7 V2 and V3 messages and content between organizations. It may also be used within organizations to exchange HL7 content, as well as legacy content, over internal networks.

"This protocol allows us to implement a single secure authenticated communications infrastructure for both legacy and emerging message standards," said Paul Knapp, contributing editor of the standard, co-chair of HL7s XML special interest group (SIG), and chief technology officer of Continovation Services Inc. "We can use it to meet current messaging and privacy needs and enable features later such as digital signatures should non-repudiation become a requirement."

Health Level Seven (HL7) also recently announced that Version 3 Standard: Patient Administration, Release 1 has passed the ballot stage and has been approved as a Draft Standard for Trial Use (DSTU). "This document is the result of five cycles of committee ballots and uncounted hours of thought by many HL7 members," said Gregg Seppala, co-chair of HL7's Patient Administration Technical Committee and contributing editor of the standard.

Patient Administration, also known as ADT (Application, Discharge and Transfer), supports many of the core administrative functions in healthcare, such as person and patient registration and encounter management.

"The challenge faced by the Patient Administration Technical Committee (TC) in rewriting Patient Administration for Version 3 was to redefine messages for a domain that has been an essential part of HL7 since the very first draft of the standard was presented in 1987," Seppala said. "After our initial analysis identified nearly 460 possible messaging events, the technical committee chose to approach writing the V3 standard incrementally."

According to Seppala, Release 1 supports 53 of the most common messaging events such as: "add a new patient," "revise demographic information about a person," and "admit an inpatient."

"We hope that Version 3 early adopters will apply our DSTU and provide feedback to guide our work on release 2," he said.

The Patient Administration domain defines person and patient demographics and visit information about patients. Generally, information is entered into a Patient or Person Registry or into a Patient Administration system and passed to other systems (e.g., other registries, clinical, ancillary and financial systems).

About the HL7 Reference Information Model (RIM)

"The HL7 RIM is a critical component of the V3 development process. It is the root of all information models and structures developed as part of the V3 development process.

The HL7 V3 standard development process is a model-driven methodology in which a network of inter-related models are developed that depict the static and behavioral aspects of the requirements and design of HL7 standards, as well as the underlying semantics and business rules that govern them.

The RIM provides a static view of the information needs of HL7 V3 standards. It includes class and state-machine diagrams and is accompanied by use case models, interaction models, data type models, terminology models, and other types of models to provide a complete view of the requirements and design of HL7 standards. The classes, attributes, state-machines, and relationships in the RIM are used to derive domain-specific information models that are then transformed through a series of constraining refinement processes to eventually yield a static model of the information content of an HL7 standard.

The HL7 V3 standard development process defines the rules governing the derivation of domain information models from the RIM and the refinement of those models into HL7 standard specifications. The rules require that all information structures in derived models be traceable back to the RIM and that their semantic and related business rules not conflict with those specified in the RIM. The RIM therefore is the ultimate source for all information content in HL7 V3 standards.

The RIM is used by HL7 international affiliates to extend HL7 V3 standards to meet local needs. Through a process known as localization, V3 standard specifications are extended using the RIM as the source for new information content. This new information is derived from the RIM and refined in the same manner used to create the original specification.

The V3 Data type specifications (Data Types Abstract Specification and V3 Data Types Implementable Technology Specification for XML) are related normative standards that are balloted independent of the RIM. The HL7 Vocabulary Domain specification is an informative reference that includes a variety of tables and terminology references that are cited as domains by various RIM attributes. The vocabulary specifications for what are termed "structural attributes" are part of the normative RIM ballot because they are fundamental to the proper representation of health information using the RIM..." [adapted from the HL7 Reference Information Model]

About Health Level Seven (HL7)

Founded in 1987, Health Level Seven, Inc. is a not-for-profit, ANSI-accredited standards developing organization dedicated to providing a comprehensive framework and related standards for the exchange, integration, sharing, and retrieval of electronic health information that supports clinical practice and the management, delivery and evaluation of health services. HL7's 2,000 members represent over 500 corporate members, including 90 percent of the largest information systems vendors serving healthcare.

International affiliates have also been established in 24 countries throughout the globe including Argentina, Australia, Brazil, Canada, China, Croatia, Czech Republic, Denmark, Finland, Germany, Greece, India, Ireland, Japan, Korea, Lithuania, Mexico, The Netherlands, New Zealand, Spain, Southern Africa, Switzerland, Taiwan and the United Kingdom.

About the OASIS ebXML Messaging Services TC

The OASIS ebXML Messaging Services Technical Committee is chartered "to develop and recommend technology for the transport, routing and packaging of business transactions using standard Internet technologies. This work [is to] foster consistency across specifications developed in other forums and carry forward the work started in the ebXML Transport, Routing and Packaging project team..."

Version 2.0 of the ebXML Message Service Specification was published by the TC in April 2002. This ebXML Message Service Protocol specification "focuses on defining a communications-protocol neutral method for exchanging electronic business messages. It defines specific enveloping constructs supporting reliable, secure delivery of business information. Furthermore, the specification defines a flexible enveloping technique, permitting messages to contain payloads of any format type. This versatility ensures legacy electronic business systems employing traditional syntaxes (i.e., UN/EDIFACT, ASC X12, or HL7) can leverage the advantages of the ebXML infrastructure along with users of emerging technologies. The specification includes descriptions of: (1) the ebXML Message structure used to package payload data for transport between parties, and (2) the behavior of the Message Service Handler sending and receiving those messages over a data communications protocol. The specification is independent of both the payload and the communications protocol used..." [from the V2.0 'Introduction']

The ebXML Messaging Services Technical Committee is working on an ebXML Messaging specification version 3.0; an initial 3.0 draft is expected to be released in July 2004, including such key work items as Header re-organization, WS-Reliability Integration, WS-Security (Point to Point), SyncReply clarification, and Payload Services. A later version scheduled for release in September 2004 will include support for additional features, including WS-I Basic Profile 1.1 (Security and Attachments), Multi-hop, Multi-hop non-repudiation, Header updates related to WS-* changes, and WS-Context. A working draft release is also available for the ebXML Messaging Services Specification 2.1.

The ebXML Message Service Specification is one of four ebXML OASIS Standards selected for publication as ISO technical specifications (ISO/TS 15000), viz., ISO 15000-2: ebXML Messaging Service Specification.