Ontology Service Architecture

The Ontology Service is a Python/FastAPI application that manages the semantic data model for the MATIH platform. It defines object types, their properties, relationships, and mappings to physical data sources. The service provides both REST and GraphQL APIs and stores ontology definitions in Dgraph.

Service Overview

Property	Value
Language	Python 3.11
Framework	FastAPI + Strawberry (GraphQL)
Port	8101
Namespace	`matih-data-plane`
Storage	Dgraph (graph store), PostgreSQL (metadata)
Source code	`data-plane/ontology-service/src/`

Sub-Pages

Page	Description
Object Types	Domain object definitions and property models
Datasource Mapping	Physical-to-logical schema mapping
Schema Validation	Ontology validation and consistency checks
GraphQL API	Strawberry GraphQL schema and resolvers
Ontology Templates	Pre-built ontology templates by industry
API Reference	Complete REST API documentation

Component Layout

ontology-service/src/
  api/
    routes/
      objects.py         -- Object type CRUD
      ontology.py        -- Ontology management
      schema_mapping.py  -- Datasource mapping endpoints
      templates.py       -- Template management
      actions.py         -- Action definitions
    graphql/
      schema.py          -- Strawberry schema definition
      types.py           -- GraphQL type definitions
      resolvers.py       -- Query and mutation resolvers
  models/
    object_type.py       -- Domain models (Pydantic)
    enums.py             -- Enumeration types
  schema_mapping/
    analyzer.py          -- Schema analysis engine
    mapper.py            -- Physical-to-logical mapper
    models.py            -- Mapping models
  templates/
    registry.py          -- Template registry
    deployer.py          -- Template deployment
    models.py            -- Template models
  storage/
    dgraph/
      client.py          -- Dgraph client
      repository.py      -- Graph repository
      migration.py       -- Schema migration
    database.py          -- PostgreSQL connection
    repository.py        -- Metadata repository

Key Concepts

Concept	Description
Object Type	A domain entity (e.g., Customer, Order, Product) with typed properties
Property	A field on an object type with data type, validation, and governance metadata
Relationship	A typed link between two object types with cardinality
Datasource Mapping	Configuration that maps a physical table/column to a logical object type/property
Ontology Template	A pre-built set of object types for a specific industry vertical

API Reference Object Types