Page Comparison

Assigned to:  Mikko Suniala 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.

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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

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• 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_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.

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