Page Comparison

Assigned to: raff

Mentor: raff

Background

OpenMRS has a mechanism to map concepts to external sources (concept_map tables); however, OpenMRS does not yet have a means to map metadata to external sources. We have tried using UUIDs to uniquely (and globally) specify metadata across systems; however, this has failed us in several ways: (1) UUIDs end up needing to be manually entered by developers and implementers; (2) there are many cases where metadata created separately (with different UUIDs) are actually referring to the same thing; and, (3) modules introducing their own metadata have a difficult time properly working with existing metadata.

...

A "1.0" version of Metadata Mapping would include a MetadataServiceMetadataService within openmrs-core (could be introduced by a module initially or for the foreseeable future) and REST API endpoints to manage & search metadata mappings.

...

Data Model Design

The following design was proposed on is based on the proposal of the Design Forum 2015-06-22:

Note that in this diagram, the one-to-one mapping between metadata_source and openmrs_metadata, for example, indicates an inheritance in object design terms: MetadataSource inherits the fields of OpenmrsMetadata. In the database schema, this relationship will be implemented so that the relation metadata_source, for example, includes all the columns of openmrs_metadata.

Notes on data model design

...

• metadata_source is used to define a unique source (authority) for each namespace of metadata terms.
  • name should be fully qualified and universally unique.
• metadata_term table _mapping table provides both the term and its mapping to local metadata.
  • code should be unique within the given source.
  • metadata_class refers to the Java class for the metadata.
  • metadata_reference is a unique reference to the metadata within the class (e.g., uuid)
• metadata_set is used to define relating grouping of metadata similar to what OpenMRS has traditionally done within global properties and similar to FHIR's ValueSet for metadata terms.
  • sort_weight is used to optionally give members of a metadata set a reliable sequence.

...

• Manage mappings (add or remove mappings, should support bulk operations)
• Search for mappings
  • By source
  • By code
  • By metadata object (given an OpenmrsMetadata instance, return any associated mappings)
• Search for metadata (given a mapping UUID or source+code, return the OpenmrsMetadata instance)

API Call examples:

Fetch a location with the given source and code:

Location location = metadataService.getItem(Location.class, "SOME-SOURCE", "CODE");
// should be implemented as: generic <T> getItem(T type, String source, String code);

Fetch all visit types from the given source:

List<VisitType> visitTypes = metadataService.getItems(VisitType.class, "SOME-SOURCE");
// should be implemented as: generic <T> getItems(T type, String source);

Fetch all visit types for the given set:

List<VisitType> visitTypes = metadataSerivce
  .getItems(VisitType.class, "SOME-SOURCE", "CODE");
// should be implemented as: generic <T> getItems(T type, String source, String code); 
// source = metadataSet.source.name, code = metadataSet.code

Retire term:

List<MetadataTermMapping> termMappings = metadataService.getMetadataTermMappings(location);
metadataService.retireMapping(termMappings.get(0), "some reason");

Create term: 

MetadataSource source = metadataService.getSourceByName("SOME-SOURCE");
MetadataTermMapping termMapping = new MetadataTermMapping(source, "CODE", location);
metadataService.saveMetadataTermMapping(termMapping);

Create terms in bulk:

List<MetadataTermMapping> termMappings = Arrays.asList(mapping1, mapping2, mapping3);
metadataService.saveMetadataTermMappings(termMappings);

Get term by source and code:

MetadataTermMapping termMapping = metadataService.getMetadataTermMapping(mappingSource, "CODE");

Get terms by source:

List<MetadataTermMapping> termMappings = metadataService.getMetadataTermMappings(source);

Get term by uuid:

MetadataTermMapping termMapping = metadataService.getMetadataTermMappingByUuid(String uuid);

Get source by uuid:

MetadataSource source = metadataService.getMetadataSourceByUuid(String uuid);

MetadataTermMapping, MetadataSource, MetadataSet should support all CRUD operations.