Reference library

Streaming & messaging

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

4 matches

Build a Streaming Messaging Helper in Python

Create a simple message stream class that stores recent messages, sends user messages, and retrieves history or latest messages with timestamps.

streaming deque dataclass

Python

from collections import deque
from dataclasses import dataclass
from datetime import datetime
import time


@dataclass
class Message:
    user: str
    text: str
    timestamp: str = ""

    def __post_init__(self):
        if not self.timestamp:
            self.timestamp = datetime.now().strftime("%H:%M:%S")


class…

13 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 medium

How to Stream Join Windowed Mock Topics in Python

Simulates two message topics and joins their events when timestamps fall within a sliding time window using Python generators and deques.

streaming join generator

Python

import itertools
import random
import time
from collections import deque
from dataclasses import dataclass, field

@dataclass
class Event:
    key: str
    value: int
    timestamp: float = field(default_factory=time.time)

def generate_topic(prefix, keys, start_time):
    while True:
        yield Event(
            …

14 0 Open

Streaming & messaging medium

Mock Watermark Late Event Side Output in Python

Simulates watermarking in a streaming pipeline by classifying events as on-time or late using timestamps and delays.

watermark streaming side output

Python

from datetime import datetime, timedelta
from typing import List, Tuple


def watermark_mock(
    events: List[Tuple[datetime, str]], watermark_delay: timedelta, max_delay: timedelta
) -> Tuple[List[Tuple[datetime, str]], List[Tuple[datetime, str]]]:
    """Simulate watermarking: events arriving on time vs. late by ch…

11 0 Open

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