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 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 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

config

Configuration system for backend-agnostic event bus readers and writers

decoder

Multi-decoder pipeline supporting multiple event types per topic

prelude

Re-export common items for convenience

Structs

BackendCapabilities

BackendDownMessage

BackendReadyMessage

BackendStatus

BusErrorContext

Context passed to error callbacks.

ConsumerMetrics

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

DecodedEventBuffer

Multi-decoded event storage that groups all successfully decoded events by topic This replaces DrainedTopicMetadata for the new multi-decoder pipeline

DrainMetricsMessage

Message emitted after each drain with snapshot metrics (optional for user systems)

DrainedTopicMetadata

Per-topic metadata-aware message buffers filled by drain system each frame

EventBusConsumerConfig

Configuration controlling how many events are drained each frame

EventBusDecodeError

Event fired when message deserialization fails

EventBusError

Event fired when any operation on the event bus fails

EventBusPlugin

Plugin for integrating with external message brokers

EventBusPlugins

Plugin bundle that configures everything needed for the event bus

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

MessageWrapper

Unified message wrapper that provides direct access to message data along with its metadata. Wrappers are only produced for externally sourced messages, so metadata is always present. The wrapper can be used directly as the message thanks to the Deref implementation.

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)

TopicDecodedEvents

Storage for all decoded events from a single topic, organized by event type

Enums

BusErrorKind

Enumerates the error kinds surfaced by writers/readers.

EventBusErrorType

Types 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.

Traits

BackendMetadata

Trait for backend-specific metadata extensions

BusEvent

Marker trait for events that can be sent/received via the event bus.

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.