Streaming & messaging
Kafka-style pub/sub, event consumers, async pipelines, and message-driven workflows.
Event Envelope with Schema Version Field in Python
Build a typed event envelope dataclass with an explicit schema version field for mock streaming scenarios.
from dataclasses import dataclass, field
from datetime import datetime
import uuid
@dataclass
class Event:
event_id: str = field(default_factory=lambda: str(uuid.uuid4()))
event_type: str = "user.created"
version: str = "1.0.0"
created_at: str = field(default_factory=lambda: datetime.utcnow().isoform…Event sourcing append store replay in Python
A simple in-memory event store that appends events per aggregate and replays them on demand.
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…Mock NATS queue group load balancing in Python
Simulates a NATS queue group where each message is delivered to exactly one subscriber using random selection with a lightweight mock.
import random
import time
from collections import defaultdict
class MockQueueGroup:
"""Mock a NATS queue group: each message is delivered to exactly one subscriber."""
def __init__(self, subscribers):
self.subscribers = subscribers
def publish(self, message):
receiver = random.choice(se…Browse by section
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Streaming & messaging — Python code examples
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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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