When building modern web or mobile applications, it’s often important to send and receive data in real time like getting new chat messages, notifications, or live updates. Here are four common ways to do that:

1. Short Polling

• What It Is: The client (like a browser) keeps asking the server for new data over and over again at fixed intervals (e.g., every 5 seconds).
• How It Works:
  • The client sends a request.
  • The server replies right away with data (if any).
  • The client waits a few seconds, then repeats the request.
• Pros:
  • Easy to set up.
  • Uses basic HTTP — no special setup needed.
• Cons:
  • Can be wasteful — sending requests even when there’s nothing new.
  • More server load and delayed updates.
• Use Case Example: Simple dashboards that refresh data every few seconds.

2. Long Polling

• What It Is: The client sends a request and waits. The server doesn’t respond until there’s new data to send (or a timeout happens).
• How It Works:
  • The client makes a request.
  • The server keeps the connection open until it has something to send.
  • When the data arrives, the server responds and the client immediately starts a new request.
• Pros:
  • Reduces unnecessary traffic — only responds when there’s new data.
  • Still works over standard HTTP.
• Cons:
  • Can tie up server resources.
  • More complex than short polling.
• Use Case Example: Comment updates on a blog or forum.

3. WebSockets

• What It Is: A fast, two-way communication channel between the client and server that stays open.
• How It Works:
  • The connection starts as a regular HTTP request, then switches (or “upgrades”) to a WebSocket connection.
  • After that, both sides can send messages anytime — instantly and continuously.
• Pros:
  • Very fast and efficient.
  • Supports real-time, bidirectional communication.
• Cons:
  • Needs both server and client to support WebSockets.
  • Harder to scale and manage compared to simple HTTP.
• Use Case Example: Chat apps, live sports scores, multiplayer games.

4. Server-Sent Events (SSE)

• What It Is: The server can send updates to the client over a single open connection — but only from server to client.
• How It Works:
  • The client makes a request to the server to start listening for updates.
  • The server keeps the connection open and pushes updates as they happen.
  • The client doesn’t have to ask again.
• Pros:
  • Simple and lightweight for one-way updates.
  • Great for sending frequent updates like stock prices or notifications.
• Cons:
  • Only works one way (server → client).
  • Doesn’t support binary data out of the box.
• Use Case Example: News tickers, live notifications, weather updates.

🧾 Summary Table

Each method has its strengths and is best suited for specific types of real-time needs. Your choice depends on:

• How often data changes
• Whether you need two-way communication
• How complex your app needs to be