Snowstorm can be used to author an extension of SNOMED CT. The SNOMED International managed service offering uses Snowstorm as the authoring Terminology Server.
- Start by setting up the code system and importing the RF2 using the loading extensions guide.
Branch metadata is used to store various items of configuration for each code system being maintained. The metadata is set on the root branch of the code system but is applies to all ancestor branches unless different values are given there. Branch metadata can be set using the update branch endpoint in the API.
| Metadata Key | Purpose | Example |
|---|---|---|
| defaultModuleId | Used during authoring. The module set on all components created or updated through the API. | "45991000052106" |
| defaultNamespace | Used during authoring. The namespace for SCTIDs generated for new components. | "1000005" |
| assertionGroupNames | Used for validation during authoring. SNOMED Drools Rule assertion group names used for validation. | "common-authoring,dk-authoring" |
| dependencyPackage | Used for classification, reporting and RVF validation. Name of RF2 archive which includes a Snapshot of the edition or extension release that this extension depends on. | "SnomedCT_InternationalRF2_PRODUCTION_20190731T120000Z.zip" |
| previousPackage | Same use as above. Name of RF2 archive which includes a Snapshot of the last release of this extension. Should not be set for new extensions. | "SnomedCT_ManagedServiceDK_PRODUCTION_DK1000005_20190930T120000Z.zip" |
| previousRelease | Used by the RVF. Effective time of the previous extension release. | "20190930" |
| dependencyRelease | Used by the RVF. Effective time of the edition or extension which this extension extends. | "20190731" |
New SNOMED components (concepts, descriptions and relationships) must have an SCTID SNOMED identifier created. Snowstorm has an SCTID generator built in which is used by default. The internal generator creates valid SCTIDs using the namespace configured in the branch metadata (see above) with the correct partition id and check digit. These identifiers are non sequential and Snowstorm checks that new identifiers are unique across all branches as part of the generation process.
Alternatively the dedicated Component Identifier Service can be used although this is a more complex setup with little benefit.
At some point you will want to upgrade the extension to use a newer International Edition.
The Snowstorm extension upgrade function supports this process by:
- Running an integrity check to find axioms which need attention.
- Automatically adding description inactivation indicators to active descriptions which reference concepts which are now inactive.
- Automatically making language reference set members inactive if they refer to descriptions which are now inactive. This is a common requirement for extensions with a large amount of translated terms.
If the integrity run as part of the upgrade finds any axioms which need attention the key value internal.integrityIssue=true is added to the code system branch metadata.
Details of axioms which reference inactive concepts can be fetched using the POST /{branch}/upgrade-integrity-check function. A branch where content fixes are being written can be supplied as an argument to this function.
When content fixes are promoted to the code system branch the integrity check will be triggered automatically, the integrity issue flag cleared if all problems are resolved.