Development schema config load

[mbuckton]

Support bundle schemas and child schema resolution

Overview

This change adds support for schema bundles in the server so that a single schema document can expose multiple usable schemas.

Two common cases are now supported:

• Protobuf descriptor bundles containing many message types
• JSON schemas containing $defs definitions

Instead of requiring each message type or definition to be stored as an individual schema, the server now:

1. Loads the bundle schema
2. Extracts child schemas from the bundle
3. Registers those children in the schema repository
4. Resolves the correct schema at message parse time

This allows topics to bind directly to individual message types or $defs entries while still using the original bundle schema as the source of truth.

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Key Changes

Schema bundle expansion

When a schema is loaded:

Protobuf

Descriptor sets are inspected and all message definitions are extracted.

Each message type becomes a child schema that references the parent descriptor bundle.

Example:

bundle.desc
 ├── package.Track
 ├── package.CommonHeader
 └── package.Telemetry

Each message is registered as a schema referencing the same descriptor bundle.

JSON

JSON schemas containing $defs are treated as bundles.

Each $defs entry becomes a child schema referencing the parent schema via JSON Pointer.

Example:

schema.json
$defs:
  Track
  CommonHeader
  Telemetry

Children are registered with pointers like:

#/$defs/Track
#/$defs/CommonHeader
#/$defs/Telemetry

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Parent-Child Schema Model

Child schemas are linked to their parent bundle.

The parent schema stores the actual schema material, while children store:

• the definition reference
• the parent relationship

This avoids duplicating large schema documents or protobuf descriptors.

---

Formatter Resolution

Formatter creation now uses a resolver so child schemas can obtain their parent bundle when needed.

SchemaManager
    ↓
SchemaResolver
    ↓
MessageFormatter

When parsing a message:

1. The child schema is selected
2. The resolver locates the parent bundle
3. The formatter loads the required definition from the bundle

This ensures:

• protobuf descriptors are not duplicated
• JSON $ref resolution continues to work
• validation occurs with full schema context

---

Topic Binding

Topics can now bind directly to:

• Protobuf message types
• JSON $defs definitions

Example:

Topic: sensors/track
Schema: Track

The server resolves Track to the correct bundle definition automatically.

---

Benefits

• Allows large schema bundles to be used directly
• Avoids duplicating schema definitions
• Supports fine-grained schema binding per topic
• Maintains full schema validation context
• Works for both Protobuf and JSON schemas

---

Testing

Tests added for:

• Protobuf message extraction from descriptor bundles
• JSON $defs extraction
• JSON pointer resolution
• JSON formatter validation using parent bundle context

---

Result

The server can now treat schema bundles as collections of usable schemas, enabling much simpler schema management for large schema sets.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
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• Commit unit tests in branch development-schema-config-load

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