Proposal for ITI Information Model Change Management

This page is documenting the proposal to significantly change the mechanisms used by the ITI domain to separate Trial Implementation content from Final Text content. This change only effects the Vol. 3 Section 4.1 currently called XDS Metadata. The committee plans to replace this section with a re-worked section which details the XD* Information Model in a clear and consistent approach. As part of that re-work the challenge of maintaining an Information Model in multiple parts (Vol. 3 Final text + Supplement Trial Implemetation text) becomes very obvious. This page documents a new approach to managing the Vol. 3 Section 4.1 in regards to the distinction between Trial Implementation and Final Text.

Problems to be Addressed

Problem One

Currently there are several Trial Implementation Supplements that are making changes to the XD* Information Model within the Supplement text. In particular are:

• Metadata Update - makes considerable changes to XD* Information Model in support of versioning metadata elements
• On-Demand Documents - defines a new Document Entry object type along with new associations

These two supplements have several interactions within the Vol. 3 text and when integrated together will probably cause some concern.

Problem Two

Anyone attempting to implement a supplement face a significant struggle to find the correct information model that applies to their work. A search of several documents is needed. For example, to implement on-demand one must review on-demand, metadata update and the base TF Vol. 3 content.

Problem Three

As the re-documentation of the XD* Information Model makes progress it will be impossible to untangle the parts that are only used within Trail Implementation supplement, not to mention which Trail Implementation supplement it belongs in. In fact, since many parts are inter-related it becomes nearly impossible for the reader to understand the larger picture with different peices spread throughout multiple supplements.

Recommended Solution

Integrate every change to the Vol. 3 XD* Information Model as part of release of Trial Implementation text.

Step 1

All supplements which contain updates to Vol. 3 Section 4.1 will be updated as follows:

• All updates to Vol. 3 Section 4.1 in the supplement will be removed
• All updates will be applied to Vol. 3 Section 4.1 Technical Framework directly, with no special markings indicating if the text is related to Trial Implementation or Final Text profiles.

Step 2

All future supplements which require changes to to Vol. 3 Section 4.1 will be processed as follows:

• Public Comment: the supplement will be released for Public Comment with the normal change tracking showing changes to Vol. 3 Section 4.1 that are needed for the supplement.
• Trial Implementation: prior to release to Trial Implementation the supplement will be updated as described in Step 1, namely, all updates related to Vol. 3 Section 4.1 will be removed from the supplement and applied directly to the Technical Framework Vol. 3 document. This step requires that new Trial Implementation supplements are released at the same time as updated TF Vol. 3. Since this is the normal process this condition is not restrictive.
• Final Text: when the profile moves to Final Text no changes to Vol. 3 Section 4.1 are needed.

But....

Some concerns regarding this change:

• But how will the implementor know what is Final Text vs. what is Trial Implementation?
  • Implementors are implementing transactions used by actors in profiles. Profiles that are in Final Text will not reference the parts of the implementation model that are in Trial Implementation. Profiles that are in Trial Implementation will reference the parts that are needed, some of which are Final Text and others are Trial Implementation. It is the references to Vol. 3 from within transactions and profiles that are normative. By itself, the information model contains no normative statements so does not need to be defined as TI or FT.
• What if after release of TI the supplement requires signficant rework of the contents of Vol.3 Section 4.1?
  • This rework will be done through the normal Change Proposal process, just as if the content were part of the supplement. The committee will be able to assess impact of a CP based on its impact to a supplement even when the actual changes go into a TF document.
• What if after release of TI the supplement is withdrawn?
  • The information model will be adjusted to remove the un-needed parts. Given the form of the information model this may not be trivial and parts may be left behind that are no longer needed. This is a minor problem, given those parts will not be referenced anywhere. We are solving bigger problems of lack of clarity in documentation which is more important than the unlikely event that some un-needed baggage is left behind from a withdrawn profile. It should be noted that ITI has so far never withdrawn a Trial Implementation profile.

And in fact!

This same approach is being considered in the development of "Volume 0" which will be a single document containing the IHE introduction currently found in most IHE volumes. Volume 0 is also going to reference (or contain) Actor definitions. The committee working on this - the documentation workgroup a subgroup of the Domain Coordination Committee - proposes that Actor definitions be added at the time of Trial Implementation release, using the same rationale as proposed early on this page.