Crate bevy_event_bus 

bevy_event_bus: Connect Bevy events to external message brokers

This crate provides an interface similar to Bevy’s MessageReader/MessageWriter but connected to external message brokers like Kafka.

Re-exports

pub use backends::EventBusBackend;

pub use backends::event_bus_backend::StreamTrimStrategy;

pub use bus_message::BusMessage;

pub use config::Kafka;

pub use config::BackendMarker;

pub use config::EventBusConfig;

pub use config::InMemory;

pub use config::ProcessingLimits;

pub use config::TopologyMode;

pub use decoder::DecodedEvent;

pub use decoder::DecoderFn;

pub use decoder::DecoderRegistry;

pub use decoder::TypedDecoder;

pub use plugins::event_bus::BackendCapabilities;

pub use plugins::event_bus::BackendDownMessage;

pub use plugins::event_bus::BackendReadyMessage;

pub use plugins::event_bus::BackendStatus;

pub use plugins::event_bus::EventBusPlugin;

pub use backends::kafka_backend::KafkaEventBusBackend;

pub use backends::redis_backend::RedisAckWorkerStats;

pub use backends::redis_backend::RedisEventBusBackend;

pub use config::kafka::KafkaBackendConfig;

pub use config::kafka::KafkaChannelCapacities;

pub use config::kafka::KafkaConnectionConfig;

pub use config::kafka::KafkaConsumerConfig;

pub use config::kafka::KafkaConsumerGroupSpec;

pub use config::kafka::KafkaInitialOffset;

pub use config::kafka::KafkaMessageMetadata;

pub use config::kafka::KafkaProducerConfig;

pub use config::kafka::KafkaTopicSpec;

pub use config::kafka::KafkaTopologyConfig;

pub use config::kafka::UncommittedEvent;

pub use config::redis::RedisBackendConfig;

pub use config::redis::RedisConnectionConfig;

pub use config::redis::RedisConsumerConfig;

pub use config::redis::RedisConsumerGroupSpec;

pub use config::redis::RedisProducerConfig;

pub use config::redis::RedisRuntimeTuning;

pub use config::redis::RedisStreamSpec;

pub use config::redis::RedisTopologyBuilder;

pub use config::redis::RedisTopologyConfig;

pub use config::redis::RedisTopologyEventBinding;

pub use config::redis::TrimStrategy;

Modules

backends

bus_message

Serializable payload types exchanged via the event bus.

config

Configuration system for backend-agnostic event bus readers and writers

decoder

Multi-decoder pipeline supporting multiple event types per topic

plugins

prelude

Re-export common items for convenience

Structs

BusErrorContext

Context passed to error callbacks registered on writers/readers.

ConsumerMetrics

Basic consumer metrics (frame-scoped counters + cumulative stats).

DrainMetricsMessage

Emitted after each drain with snapshot metrics (optional for user systems).

DrainedTopicMetadata

Per-topic message buffers filled by the drain system and consumed by readers.

EventBusConsumerConfig

Configuration controlling how many events are drained each frame.

EventBusError

Event fired when any operation on the event bus fails.

KafkaMessageReader

Kafka-specific BusMessageReader implementation that can optionally perform manual commits and expose consumer lag metrics.

KafkaMessageWriter

Kafka-specific writer that extends the generic message writer with partition keys, headers and flush support.

KafkaMetadata

Kafka-specific metadata

MessageMetadata

Generic message metadata that works across all backends

MessageQueue

Channel receiver resource for background consumer -> main thread.

MessageWrapper

Unified message wrapper that provides direct access to message data along with its metadata.

ProcessedMessage

Pre-processed message with payload and metadata already converted for efficient reading.

ProvisionedTopology

Tracks the provisioned backend topologies so readers can validate configuration without touching backend internals. Only one backend of each type is expected to be active.

RedisMessageReader

Redis-specific BusMessageReader implementation that exposes manual acknowledgements.

RedisMessageWriter

Redis-specific writer that provides stream trimming and configuration-driven options.

SharedRuntime

Bevy resource wrapper for a shared Tokio runtime (Arc for cheap clone into async tasks)

Enums

EventBusErrorType

Categories of errors that can occur in the event bus.

KafkaReaderError

Errors that can occur when working with the Kafka-specific reader.

KafkaWriterError

Errors emitted by the Kafka-specific writer when backend operations fail.

RedisReaderError

Errors that can occur when working with the Redis-specific reader.

RedisWriterError

Errors emitted by the Redis-specific writer when backend operations fail.

Constants

DEFAULT_MAX_RETAINED_PER_TOPIC

Default upper bound on the number of messages retained per topic.

Traits

BackendMetadata

Trait for backend-specific metadata extensions

BusMessageReader

Common capabilities shared by all bus message readers.

BusMessageWriter

Common interface shared by all outbound message writers.

Functions

block_on

Block on a future using the shared runtime.

ensure_runtime

Ensure a SharedRuntime resource exists in the provided app.

runtime

Get a reference to the shared Tokio runtime (Arc inside OnceCell)

Type Aliases

BusErrorCallback

Callback invoked when an error occurs.