Streaming & messaging
Kafka-style pub/sub, event consumers, async pipelines, and message-driven workflows.
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.
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…How to Partition and Order Kafka-Style Messages by Key in Python
Group messages with the same key into ordered buckets using hashing and a defaultdict, mimicking Kafka partition ordering.
from dataclasses import dataclass
from collections import defaultdict
@dataclass
class Message:
key: str
content: str
def partition_and_order(messages, num_partitions=3):
partitions = defaultdict(list)
for msg in messages:
partition_id = hash(msg.key) % num_partitions
partitions[parti…Browse by section
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Streaming & messaging — Python code examples
What you will find here
This page collects streaming & messaging snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
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Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.