Crate helios_subscriptions 

FHIR topic-based Subscriptions engine for HFS.

This crate implements the FHIR Subscriptions Framework for the Helios FHIR Server. It supports topic-based subscriptions across all FHIR versions (R4, R4B, R5, R6), with R4 using the Subscriptions R5 Backport IG and R4B/R5/R6 using native subscription resources.

Architecture

The subscription system decomposes into five primary concerns:

• Topic Registry — stores SubscriptionTopic definitions and evaluates triggers
• Subscription Manager — CRUD lifecycle and status tracking for Subscription resources
• Event Evaluator — matches resource write events against active subscriptions
• Notification Builder — constructs version-specific notification bundles
• Channel Dispatcher — delivers notifications via rest-hook, WebSocket, etc.

The SubscriptionEngine orchestrates all five concerns and is the main entry point, invoked asynchronously after each resource write.

Re-exports

pub use channels::messaging::MessagingChannel;

pub use channels::ws_manager::WebSocketManager;

pub use channels::ws_token::WsBindingTokenManager;

pub use config::MessagingSettings;

pub use config::SubscriptionConfig;

pub use engine::SubscriptionEngine;

pub use error::SubscriptionError;

pub use event::ResourceEvent;

pub use event::ResourceEventType;

Modules

channels

Channel dispatchers.

config

Subscription engine configuration.

engine

Subscription engine — the orchestrator.

error

Subscription error types.

evaluator

Event evaluator.

event

Resource event types emitted after write operations.

manager

Subscription manager.

notification

Notification builder.

topics

Subscription topic registry.