Reference library

Streaming & messaging

Kafka-style pub/sub, event consumers, async pipelines, and message-driven workflows.

3 matches

Dead Letter Queue Failed Messages List Mock in Python

Implements a simple in-memory dead letter queue to collect, list, and retry failed messages, with JSON serialization for inspection in streaming pipelines.

dead-letter-queue messaging retry

Python

import json
from collections import deque


class Message:
    def __init__(self, message_id, payload, attempts=0):
        self.message_id = message_id
        self.payload = payload
        self.attempts = attempts

    def __repr__(self):
        return f"Message(id={self.message_id}, attempts={self.attempts})"


c…

15 0 Open

Streaming & messaging medium

How to Implement At-Least-Once Delivery with Acknowledgment in Python

This code demonstrates a mock message broker with at-least-once delivery, including retry logic and acknowledgment after successful processing.

messaging queue retry

Python

import time
import uuid
from collections import deque


class MockMessageBroker:
    def __init__(self):
        self.queue = deque()
        self.acked = set()

    def publish(self, payload: str) -> str:
        msg_id = str(uuid.uuid4())
        self.queue.append((msg_id, payload))
        return msg_id

    def po…

13 0 Open

Streaming & messaging medium

Implement a retry queue with visibility timeout in Python

This code simulates a message queue with a visibility timeout, allowing messages to be retried if not deleted before the timeout expires.

queue retry visibility-timeout

Python

import time
from collections import deque


class SimpleQueue:
    def __init__(self, visibility_timeout=2):
        self.queue = deque()
        self.in_flight = {}
        self.visibility_timeout = visibility_timeout

    def send(self, message):
        self.queue.append(message)

    def receive(self):
        if …

13 0 Open

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