The purpose of this page is to analyze the interaction of the SOAP/IHE protocol with REST/email protocol options, and creating a list of clear functional requirements for NHIN Direct messaging and its constituent parts.

Assumptions and Definitions

Trusted HISP: A HISP which has access to PHI
Non-trusted HISP: A HISP which has no access to PHI
XDR: The XDR IHE profile, with at least the minimal metadata wrapper (initial description) and enhancements as discovered as part of the lessons learned, namely adding the To: and From: addresses to the SOAP header, allowing for the body to be encrypted using WS-Security - X.509 profile.
XDM: The ZIP archive based on the IHE XDM profile.
SOAP-based Web Services (WS-*): A set of standards by the W3C and OASIS, further profiled by the Web Services Interoperability Organization. The SOAP/IHE transactions under discussion use the following WS-* specifications: SOAP 1.2, XOP/MTOM, Web Services Addressing, and (if necessary) WS-Security - X.509 profile.

General Description

The goal we are trying to achieve is one Nationwide Health Information Network. NHIN Direct and NHIN Exchange participants need to reach each other, and at the same time participating in either should be made easy for the users. The following diagram attempts to illustrate that goal:
The diagram shows how the capabilities of a HISP can serve the various capabilities of the sources and destinations, without forcing additional functionality on participants who do not need it. For those participants in the NHIN for whom NHIN Direct is the first step, the capabilities of the HISP as described in the NHIN Direct Convergence Proposal can present the path for future participation in the NHIN with its full assortment of services. The only slight modification to the current NHIN Direct Convergence Proposal is to clarify that the XDR Gateway capabilities include the ability to send and receive XDR transactions (as defined in the context of NHIN Direct).

Details of Implementation

A discussion on capabilities of Sources, Destinations, and HISPs resulted in Keith Boone's blog post. An illustrated version of that post is presented here:

The Overall View

A Talks to A
A talks to B or C

B or C talks to B or C
B talks to A

C talks to A