Reference library

Streaming & messaging

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

4 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 easy

Event sourcing append store replay in Python

A simple in-memory event store that appends events per aggregate and replays them on demand.

event-sourcing append-only replay

Python

import json
from collections import defaultdict


class EventStore:
    def __init__(self):
        self._events = defaultdict(list)

    def append(self, aggregate_id, event_type, data):
        event = {"type": event_type, "data": data}
        self._events[aggregate_id].append(event)

    def replay(self, aggregate…

14 0 Open

Streaming & messaging easy

How to Implement an In-Memory Pub/Sub System in Python

This code implements a simple in-memory publish/subscribe system in Python, allowing topics, callbacks, and message broadcasting.

pubsub event-driven design-pattern

Python

class PubSub:
    def __init__(self):
        self.topics = {}

    def subscribe(self, topic, callback):
        if topic not in self.topics:
            self.topics[topic] = []
        self.topics[topic].append(callback)
        return lambda: self.unsubscribe(topic, callback)

    def unsubscribe(self, topic, callb…

18 0 Open

Streaming & messaging easy

Redis Pub/Sub Channel Subscribe Mock in Python

A lightweight in-memory mock of Redis pub/sub that lets you subscribe to channels, publish messages, and verify handler behavior in tests without a real Redis server.

redis pubsub testing

Python

class MockRedisPubSub:
    def __init__(self):
        self.channels = {}

    def subscribe(self, channel):
        if channel not in self.channels:
            self.channels[channel] = []
        return self.channels[channel]

    def publish(self, channel, message):
        if channel in self.channels:
            …

11 0 Open

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