Load Testing & Performance Benchmarking (JMeter & k6) · 강의

WebSocket 및 스트리밍 테스트

WebSockets와 스트리밍 프로토콜을 사용하여 실시간 애플리케이션의 성능을 테스트하는 방법을 살펴봅니다.

WebSocket 및 스트리밍 테스트은(는) CoddyKit의 무료 Load Testing & Performance Benchmarking (JMeter & k6) 강의입니다. 이것은 4개 중 3번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 Load Testing & Performance Benchmarking (JMeter & k6) 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. Load Testing & Performance Benchmarking (JMeter & k6) 강의에는 총 4개의 강의가 포함되어 있습니다.

이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.

Real-Time Apps Need Special Tests

Chat applications, live dashboards, and online games are examples of real-time applications. They demand constant, fast updates and immediate interaction.

Traditional HTTP testing, which relies on a request-response model, doesn't fully capture the behavior of these dynamic systems. We need specific tools and methods to test them effectively.

Understanding WebSockets

WebSockets provide a persistent, bi-directional communication channel over a single TCP connection. This means both the client and server can send data to each other at any time.

Unlike HTTP, which opens and closes connections for each request, WebSockets establish an initial 'handshake' and then maintain an open connection for continuous, 'full-duplex' communication. This makes them ideal for real-time interactions.

Unique Challenges of WebSocket Testing

Performance testing WebSockets presents distinct challenges compared to traditional HTTP:

Persistent Connections: Simulating many open, long-lived connections for extended durations.
Bi-directional Flow: Handling messages sent by both client and server asynchronously.
Dynamic Content: Validating constantly updating data streams rather than static responses.

Our testing tools must be capable of managing these continuous interactions.

JMeter for WebSocket Load Testing

JMeter can be extended to test WebSockets using third-party plugins (e.g., the WebSocket Samplers by Maciej Zaleski).

These plugins allow you to:

Open and close WebSocket connections.
Send messages to the server.
Listen for and capture incoming messages.

You'll configure these steps within JMeter's graphical user interface (GUI).

Configuring a JMeter WebSocket Test

To establish a WebSocket connection in JMeter, you typically add a 'WebSocket Open Connection' sampler. Here, you specify the WebSocket URL (ws:// or wss://).

Subsequent 'WebSocket Request' samplers can then be used to send messages. To end the connection, a 'WebSocket Close' sampler is used. You can also add 'Response Assertions' to validate received messages.

k6: Scripting WebSocket Tests with JavaScript

k6 offers native support for WebSockets through its ws module, making it a powerful and flexible choice for real-time testing.

You write your test logic in JavaScript, defining how virtual users interact with the WebSocket server. This provides great flexibility for creating complex, stateful scenarios that accurately simulate user behavior.

Basic k6 WebSocket Connection

Let's see how to establish a simple WebSocket connection with k6. This script connects to a public test WebSocket echo server and then immediately closes the connection.

import ws from 'k6/ws';
import { check } from 'k6';

export default function () {
  const url = 'ws://echo.websocket.events/'; // A public echo server
  const params = { tags: { ws_tag: 'hello' } };

  const res = ws.connect(url, params, function (socket) {
    socket.on('open', () => console.log('Connected!'));
    socket.on('close', () => console.log('Disconnected!'));
    socket.on('error', (e) => console.log('Error:', e.error()));

    socket.close(); // Close immediately after connecting
  });

  check(res, { 'status is 101': (r) => r && r.status === 101 });
}

Sending and Receiving Messages in k6

Now, let's extend our k6 script to send a message and wait for a response from the echo server. We use socket.send() to transmit data and handle incoming messages with socket.on('message').

import ws from 'k6/ws';
import { check } from 'k6';

export default function () {
  const url = 'ws://echo.websocket.events/';

  ws.connect(url, null, function (socket) {
    socket.on('open', () => {
      console.log('Connected, sending message...');
      socket.send('Hello CoddyKit!');
    });

    socket.on('message', (data) => {
      console.log('Received:', data);
      check(data, { 'message is "Hello CoddyKit!"': (d) => d === 'Hello CoddyKit!' });
      socket.close(); // Close after receiving the message
    });

    socket.on('close', () => console.log('Disconnected!'));
    socket.on('error', (e) => console.log('Error:', e.error()));

    // Keep the VU alive until a message is received or timeout
    socket.prune();
  });
}

Ensuring Correctness with k6 Checks

Just like with HTTP requests, you need to validate the content of WebSocket messages to ensure the real-time data flow is correct under load.

k6's check() function is perfect for this. You can assert on the message content, format, or specific fields received from the server.

import ws from 'k6/ws';
import { check } from 'k6';

export default function () {
  const url = 'ws://echo.websocket.events/';
  const expectedMessage = 'Test Message 123';

  ws.connect(url, null, function (socket) {
    socket.on('open', () => {
      socket.send(expectedMessage);
    });

    socket.on('message', (data) => {
      console.log('Received:', data);
      check(data, {
        'received message matches sent': (d) => d === expectedMessage,
        'message length is correct': (d) => d.length === expectedMessage.length,
      });
      socket.close();
    });

    socket.on('close', () => console.log('Disconnected!'));
    socket.on('error', (e) => console.log('Error:', e.error()));

    socket.prune();
  });
}

Testing Other Streaming Protocols

While WebSockets are popular, other streaming protocols exist:

Server-Sent Events (SSE): A uni-directional protocol where the server pushes updates to the client. Easier for simple data feeds.
gRPC Streaming: Uses HTTP/2 for efficient bi-directional streaming, often favored in microservices architectures. Requires specialized gRPC testing tools.

Each protocol has its own testing considerations and may require dedicated tools or libraries.

Quick Check

Consider a real-time chat application where users constantly send and receive messages. Which statement best describes why WebSockets are generally preferred over traditional HTTP for this scenario?

Recap: Mastering Real-Time Tests

We've explored the unique challenges of testing real-time applications using WebSockets and streaming protocols.

You learned that:

WebSockets offer persistent, bi-directional communication.
JMeter (with plugins) and k6 (native support) are key tools for testing them.
k6 provides flexible JavaScript scripting for complex scenarios.
Validation of dynamic messages using checks is crucial.

Understanding these concepts is vital for ensuring the performance of modern, interactive applications.

자주 묻는 질문

“WebSocket 및 스트리밍 테스트” 강의는 무료인가요?

네 — “WebSocket 및 스트리밍 테스트” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 Load Testing & Performance Benchmarking (JMeter & k6) 강의 전체를 잠금 해제할 수 있습니다. Load Testing & Performance Benchmarking (JMeter & k6) 강의에는 총 4개의 강의가 포함되어 있습니다.

“WebSocket 및 스트리밍 테스트”에서 뭘 배우나요?

WebSockets와 스트리밍 프로토콜을 사용하여 실시간 애플리케이션의 성능을 테스트하는 방법을 살펴봅니다. 브라우저에서 직접 실행하는 실습 코드로 Load Testing & Performance Benchmarking (JMeter & k6)을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.

Load Testing & Performance Benchmarking (JMeter & k6)을(를) 시작하는 데 경험이 필요한가요?

사전 경험은 필요하지 않습니다. CoddyKit의 Load Testing & Performance Benchmarking (JMeter & k6)은(는) 초급자부터 고급 학습자까지를 위해 구성되어 있으므로, 여기서 시작하거나 처음부터 시작할 수 있으며 자신의 속도대로 진행할 수 있습니다. 이것은 4개 중 3번째 강의입니다.

“WebSocket 및 스트리밍 테스트” 강의는 얼마나 걸리나요?

대부분의 CoddyKit 강의는 약 5~10분이 소요됩니다. 각 강의는 간결하고 인터랙티브하여 꾸준한 진행이 가능하며, 웹과 앱에서 중단한 부분부터 바로 시작할 수 있습니다.

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네. 모든 Load Testing & Performance Benchmarking (JMeter & k6) 강의에는 내장 코드 에디터가 포함되어 있으므로, 브라우저에서 바로 실제 코드를 작성하고 실행한 후 즉시 AI 피드백을 받을 수 있습니다 — 로컬 설정이 필요 없습니다.

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