danube-client 0.6.0

The async client for Danube Messaging Broker platform
Documentation

Danube Client

An async Rust client library for interacting with Danube Messaging platform.

🌊 Danube Messaging is an open-source distributed Messaging Broker platform written in Rust. Consult the documentation for supported concepts and the platform architecture.

Features

📤 Producer Capabilities

  • Basic Messaging - Send messages with byte payloads and optional key-value attributes
  • Partitioned Topics - Distribute messages across multiple partitions for horizontal scaling
  • Reliable Dispatch - Guaranteed message delivery with persistence (WAL + cloud storage)
  • Schema Integration - Type-safe messaging with automatic validation (Bytes, String, Number,Avro, JSON Schema, Protobuf)

📥 Consumer Capabilities

  • Flexible Subscriptions - Three subscription types for different use cases:
    • Exclusive - Single active consumer, guaranteed ordering
    • Shared - Load balancing across multiple consumers, parallel processing
    • Failover - High availability with automatic standby promotion
  • Message Acknowledgment - Reliable message processing with at-least-once delivery
  • Partitioned Consumption - Automatic handling of messages from all partitions
  • Batch Processing - Efficient batch consumption for high-throughput scenarios
  • Message Attributes - Access metadata and custom headers

🔐 Schema Registry

  • Schema Management - Register, version, and retrieve schemas (JSON Schema, Avro, Protobuf)
  • Compatibility Checking - Validate schema evolution (Backward, Forward, Full, None modes)
  • Type Safety - Automatic validation against registered schemas
  • Schema Evolution - Safe schema updates with compatibility enforcement
  • Startup Validation - Validate consumer structs against schemas before processing

🏗️ Client Features

  • Async/Await - Built on Tokio for efficient async I/O
  • Connection Pooling - Shared connection management across producers/consumers
  • Automatic Reconnection - Resilient connection handling
  • Topic Namespaces - Organize topics with namespace structure (/namespace/topic-name)

Example Usage

Check out the example files.

Producer

let client = DanubeClient::builder()
    .service_url("http://127.0.0.1:6650")
    .build()
    .unwrap();

let topic_name = "/default/test_topic";
let producer_name = "test_prod";

let mut producer = client
    .new_producer()
    .with_topic(topic_name)
    .with_name(producer_name)
    .build();

producer.create().await?;
println!("The Producer {} was created", producer_name);

let encoded_data = "Hello Danube".as_bytes().to_vec();

let message_id = producer.send(encoded_data, None).await?;
println!("The Message with id {} was sent", message_id);

Consumer

let client = DanubeClient::builder()
        .service_url("http://127.0.0.1:6650")
        .build()
        .unwrap();

    let topic = "/default/test_topic";
    let consumer_name = "test_cons";
    let subscription_name = "test_subs";

    let mut consumer = client
        .new_consumer()
        .with_topic(topic)
        .with_consumer_name(consumer_name)
        .with_subscription(subscription_name)
        .with_subscription_type(SubType::Exclusive)
        .build();

    // Subscribe to the topic
    consumer.subscribe().await?;
    println!("The Consumer {} was created", consumer_name);

    // Start receiving messages
    let mut message_stream = consumer.receive().await?;

    while let Some(message) = message_stream.recv().await {
        let payload = message.payload;

        match String::from_utf8(payload) {
            Ok(message_str) => {
                println!("Received message: {:?}", message_str);

                consumer.ack(&message).await?;
            }
            Err(e) => println!("Failed to convert Payload to String: {}", e),
        }
    }

Advanced Features

For detailed guides and examples on advanced capabilities:

Browse the examples directory for complete working code.

Contribution

Check the documentation on how to setup a Danube Broker.