This document specifies a technical architecture designed by Markle Connecting for Health for communication of protected health information between sub-network organizations (SNOs) on a Nationwide Health Information Network (NHIN). The architecture and messaging standards discussed here make up part of Markle Connecting for Health's Common Framework, a proposed collection of technical standards and policies designed to make it possible to build a NHIN that is effective and achievable in incremental steps, and supports the required discovery and transport of patient records between authorized parties while protecting those records from unauthorized access or use.
The technical goal of the Common Framework is to define a minimal set of commonly adhered to standards and policies that allow for the SNO-based implementation of health information networks that are nationally interoperable. In the Markle Connecting for Health view, the National Health Information Network is an interoperable network of networks, achieved through incremental creation of Common Framework-compliant SNOs.
In addition to the messaging standards, it provides information to support the implementation of Record Locator Service (RLS) and Inter-SNO Bridge (ISB) communication services, including messaging protocols, standards, authentication, and security for the transactions. The RLS is a community Master Patient Index (MPI) that stores only the location of patient records, plus enough demographic details to match a query with the appropriate records, and is designed to let entities within a SNO locate one another's records. The ISB is the interface for communications between entities in different SNOs. The RLS and the ISB have been designed to be platform-neutral. Although the RLS will be, in practice, databases accessible through secure web servers, the definition of a Common Framework-compliant RLS or ISB has to do with interfaces, messages, and behaviors, not with any particular technology.
The NHIN assumes the use of encrypted communications over the internet among participants, and models all interactions as Web Services conversations in SOAP. (This document assumes a familiarity with the Web standards SSL, XML 1.0, and SOAP 1.1, as well as the clinical standard HL7 2.4; we do not reproduce the documentation for those standards here.) Modeling the NHIN transactions in SOAP provides a degree of flexibility to support various messaging types within a single framework. The messages described here also support exchange of some types of non-protected information. Due to the generic nature of the NHIN query message structure, we anticipate extending the architecture to support additional types of communications required by a NHIN, from additional forms of clinical information to administrative messages.