Merancang Obrolan Waktu Nyata
Terapkan aplikasi obrolan waktu nyata dasar yang menunjukkan penggunaan Pub/Sub untuk pengiriman pesan.
Merancang Obrolan Waktu Nyata adalah pelajaran Redis Caching & Messaging (Pub/Sub, Streams) gratis di CoddyKit. Ini adalah pelajaran 2 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Redis Caching & Messaging (Pub/Sub, Streams), dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Redis Caching & Messaging (Pub/Sub, Streams) mencakup 4 pelajaran total.
Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.
Real-time Chat with Pub/Sub
Imagine building a chat application where messages appear instantly! This is where Redis Pub/Sub shines. It's perfect for real-time communication without constant 'checking for new messages'.
In this lesson, you'll learn how to design a basic chat system using Redis Publish/Subscribe, turning chat rooms into channels and messages into published events.
Chat Rooms as Redis Channels
The core idea for a chat application with Pub/Sub is simple: each chat room corresponds to a unique Redis Channel.
- When a user wants to join a chat room (e.g., 'general' or 'support'), their client application will subscribe to the corresponding Redis channel.
- When a user sends a message in that room, their client will publish the message to that specific channel.
Subscribing to Join a Room
To 'join' a chat room, a client needs to start listening for messages on its channel. This is done by subscribing. Once subscribed, the client will receive all messages published to that channel.
Below is a simplified Java example using a Redis client library (like Jedis) to subscribe to a channel named chat:general.
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPubSub;
public class ChatSubscriber {
public static void main(String[] args) {
try (Jedis jedis = new Jedis("localhost")) {
System.out.println("Subscribing to chat:general...");
jedis.subscribe(new JedisPubSub() {
@Override
public void onMessage(String channel, String message) {
System.out.println("Received on " + channel + ": " + message);
}
}, "chat:general");
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
}
}Publishing to Send Messages
When a user types a message and hits 'send', their client application will publish that message to the channel corresponding to the current chat room. All clients currently subscribed to that channel will immediately receive the message.
This Java example shows how a client would publish a message to the chat:general channel.
import redis.clients.jedis.Jedis;
public class ChatPublisher {
public static void main(String[] args) {
try (Jedis jedis = new Jedis("localhost")) {
String message = "Hello, everyone!";
jedis.publish("chat:general", message);
System.out.println("Published: '" + message + "'");
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
}
}Demo: User A Listens
Let's see this in action! Run this program in one terminal. It simulates User A joining the chat:general room and waiting for messages. It will block and print any message it receives.
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPubSub;
public class UserA {
public static void main(String[] args) {
try (Jedis jedis = new Jedis("localhost")) {
System.out.println("User A is listening on chat:general...");
jedis.subscribe(new JedisPubSub() {
@Override
public void onMessage(String channel, String message) {
System.out.println("User A received: " + message);
}
}, "chat:general");
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
}
}Demo: User B Sends
Now, open a separate terminal and run this program. It simulates User B sending a message to the chat:general room. Watch User A's terminal – it should instantly receive User B's message!
import redis.clients.jedis.Jedis;
public class UserB {
public static void main(String[] args) {
try (Jedis jedis = new Jedis("localhost")) {
String message = "Hey User A, are you there?";
jedis.publish("chat:general", message);
System.out.println("User B published: '" + message + "'");
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
}
}Designing Your Chat Message
A simple string message isn't usually enough for a chat application. You'll want to include more context. A common approach is to serialize chat message data into a format like JSON before publishing it.
Consider including:
sender: The username or ID of who sent the message.timestamp: When the message was sent (for ordering).text: The actual content of the message.roomId: (Optional) The channel/room ID, useful for client-side processing.
Handling Multiple Chat Rooms
To support many different chat rooms (e.g., 'general', 'private:alice-bob', 'developers'), you simply use different channel names.
- Each room gets a unique channel name (e.g.,
chat:general,chat:support). - Clients subscribe only to the channels of the rooms they are active in.
- When a user switches rooms, their client unsubscribes from the old channel and subscribes to the new one.
Pub/Sub's Non-Persistent Nature
It's crucial to remember that Redis Pub/Sub is a fire-and-forget system. Messages are delivered to all currently active subscribers and then disappear.
- If a user is offline or not subscribed when a message is published, they will not receive that message when they come back online.
- For persistent chat history or messages to offline users, you would need to combine Pub/Sub with other Redis data structures (like Lists or Streams) or a separate database.
Chat Design Quiz
You're building a chat app with Redis Pub/Sub. Users join rooms by subscribing to channels. If User A is subscribed to chat:tech and User B publishes a message to chat:random, what happens?
Recap: Real-time Chat Design
You've learned the basics of designing a real-time chat application using Redis Pub/Sub:
- Each chat room maps to a unique Redis channel.
- Users subscribe to a channel to join a room and receive messages.
- Users publish messages to a channel to send them to all subscribers.
- Messages should be structured (e.g., JSON) to include sender, timestamp, and content.
- Remember that Pub/Sub is non-persistent; messages are gone once delivered.
This foundation allows for highly responsive chat experiences!
Belajar Redis Caching & Messaging (Pub/Sub, Streams) dengan tutor AI — gratis
Tulis dan jalankan kode asli di browser kamu, dapatkan bantuan instan dari tutor AI 24/7, dan lanjutkan di mana kamu tinggalkan di web atau aplikasi.
- Kursus
- 12
- Pelajaran
- 48
Pertanyaan yang Sering Diajukan
Apakah pelajaran “Merancang Obrolan Waktu Nyata” gratis?
Ya — teks lengkap “Merancang Obrolan Waktu Nyata” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Redis Caching & Messaging (Pub/Sub, Streams), upgrade ke CoddyKit PRO. Kursus Redis Caching & Messaging (Pub/Sub, Streams) mencakup 4 pelajaran total.
Apa yang akan aku pelajari di “Merancang Obrolan Waktu Nyata”?
Terapkan aplikasi obrolan waktu nyata dasar yang menunjukkan penggunaan Pub/Sub untuk pengiriman pesan. Kamu berlatih Redis Caching & Messaging (Pub/Sub, Streams) dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.
Apakah aku perlu pengalaman untuk memulai Redis Caching & Messaging (Pub/Sub, Streams)?
Tidak diperlukan pengalaman sebelumnya. Redis Caching & Messaging (Pub/Sub, Streams) di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 2 dari 4.
Berapa lama pelajaran “Merancang Obrolan Waktu Nyata” memakan waktu?
Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.
Bisakah aku menulis dan menjalankan kode dalam pelajaran Redis Caching & Messaging (Pub/Sub, Streams) ini?
Ya. Setiap pelajaran Redis Caching & Messaging (Pub/Sub, Streams) menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.
Semua pelajaran dalam kursus ini
- Langganan Pencocokan Pola
- Merancang Obrolan Waktu Nyata
- Arsitektur Berbasis Peristiwa
- Melacak Kehadiran dan Status Daring