ros2_medkit_graph_provider

Gateway plugin that provides ROS 2 topic graph analysis with latency, frequency, and drop-rate metrics. This is the default IntrospectionProvider - extracted from ros2_medkit_gateway into a standalone plugin package in v0.4.0.

What It Does

• Subscribes to /diagnostics for hardware-level metrics
• Builds a topic graph with per-topic metrics: frequency (Hz), latency (ms), drop rate (%)
• Detects stale topics with no recent data
• Tracks which nodes published to which topics
• Provides graph state snapshots via the x-medkit-graph vendor extension endpoint

Configuration

Loaded as a gateway plugin via gateway.launch.py (configured by default):

plugins: ["graph_provider"]
plugins.graph_provider.path: "/path/to/libros2_medkit_graph_provider.so"
plugins.graph_provider.expected_frequency_hz: 30.0

Architecture

The plugin implements GatewayPlugin + IntrospectionProvider:

• GraphProviderPlugin - Main plugin class with ROS 2 subscriptions
• GraphBuildState - Internal state tracking topic metrics and staleness
• GraphBuildConfig - Configuration (expected frequency defaults)

Entity cache is populated from the ROS 2 graph during each discovery cycle via the merge pipeline’s PluginLayer.

License

Apache License 2.0

Changelog for package ros2_medkit_graph_provider

0.4.0 (2026-03-20)

• Initial release - extracted from ros2_medkit_gateway package
• GraphProviderPlugin for ROS 2 graph-based entity introspection
• Standalone external plugin package with independent build and test
• Locking support via PluginContext API
• Contributors: \@bburda