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…

16 0 Open

Streaming & messaging easy

How to Build a Mock Change Data Capture Event Stream in Python

Generate a deterministic list of mock CDC events with event IDs, stream positions, payloads, and timestamps for testing streaming pipelines.

cdc mock event-stream

Python

from itertools import count
from random import choice, randint, seed
from datetime import datetime, timedelta

seed(42)  # Make output deterministic
event_types = ["INSERT", "UPDATE", "DELETE"]
table_names = ["users", "orders", "products", "payments"]
counter = count(1)

def mock_cdc_event(stream_index: int) -> dict:
…

12 0 Open

Streaming & messaging easy

How to Mock Kafka Topic Partitions with a Python dict of lists

Mocks a Kafka topic and its partitions using a defaultdict of lists to simulate message production, consumption, and per-partition counts.

kafka mock partitions

Python

from collections import defaultdict

class KafkaTopicPartitionMock:
    """A simple mock for Kafka topic-partition assignment using dict of lists."""

    def __init__(self, topic):
        self.topic = topic
        self.partitions = defaultdict(list)  # partition_id -> list of messages

    def produce(self, message…

15 0 Open

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