Send & Receive

Overview

Queue send/receive is the foundational operation for guaranteed-delivery, point-to-point messaging: you reach for it whenever work needs to survive past the moment it's created and be handled by exactly one consumer, not broadcast to every subscriber. Unlike pub/sub, a queued message sits durably on the broker until something pulls it, so the producer and consumer never need to be online at the same time — a slow or offline worker adds latency, it doesn't drop the message.

This tutorial builds the smallest possible version of that round trip: send_queue_message enqueues a message on a channel, and receive_queue_messages pulls it back with a bounded wait_time_seconds. The is_peek flag controls whether receiving consumes the message — false removes it from the queue on delivery, while true reads it without removing it.

Gotchas: with is_peek set to false, the message is considered handled the moment it's delivered — if your handler crashes right after receiving, that message is already gone with no chance to retry. Polling an empty queue isn't an error; it just returns an empty vector once the timeout elapses. And max_messages caps how many messages one call can return, so don't assume a single receive_queue_messages call drains the whole queue.

Prerequisites

• KubeMQ server running on localhost:50000
• Rust SDK installed (cargo add kubemq)

Code

use kubemq::prelude::*;
use kubemq::QueueMessageBuilder;

#[tokio::main]
async fn main() -> kubemq::Result<()> {
    let client = KubemqClient::builder()
        .host("localhost")
        .port(50000)
        .build()
        .await?;

    let channel = "rust-queues.send-receive";

    let msg = QueueMessageBuilder::new()
        .channel(channel)
        .body(b"Hello Queue!".to_vec())
        .metadata("queue-metadata")
        .build();

    let result = client.send_queue_message(msg).await?;
    println!(
        "Sent: message_id={}, sent_at={}",
        result.message_id, result.sent_at
    );

    let messages = client.receive_queue_messages(channel, 10, 5, false).await?;

    for m in &messages {
        println!(
            "Received: id={}, body={}",
            m.id,
            String::from_utf8_lossy(&m.body)
        );
    }

    println!("Total received: {}", messages.len());

    client.close().await?;
    Ok(())
}

How It Works

• send_queue_message persists the message and returns a QueueSendResult with server timestamps.
• receive_queue_messages pulls up to max_messages with a wait_time_seconds timeout.
• Setting is_peek to false consumes messages; true reads without consuming.
• Review timeouts, channel names, and client IDs before running against shared environments.
• Run the program while the server from the prerequisites is available.

Related

• Queues overview
• Rust SDK Reference
• Batch Send
• Peek Messages