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KeepAlive Mechanism

The KeepAlive system ensures that an active session stays alive and responsive.
It prevents unintentional timeouts due to inactivity by periodically sending small packets.

🔁 How It Works​

  • After a successful handshake, both client and server start sending KeepAlive packets
  • Each KeepAlive is sent at a fixed interval (e.g. every 5 seconds)
  • If no message or KeepAlive is received from the other side within the inactivity timeout window, the connection is closed

🧠 Configuration​

You can configure both interval and timeout using setKeepAliveConfig(...):

server.setKeepAliveConfig(keepAliveIntervalMs, inactivityTimeoutMs);
client.setKeepAliveConfig(keepAliveIntervalMs, inactivityTimeoutMs);
  • keepAliveIntervalMs: how often to send a KeepAlive (must be < timeout)
  • inactivityTimeoutMs: max allowed silence before disconnection Use -1 to disable the timeout check completely

📦 What Is Sent?​

A KeepAlive packet contains only 1 byte:

  • TYPE: 0x05
  • It is not encrypted

These are small and lightweight, they do not carry any actual message content.

🚨 What If It Fails?​

If the other side becomes unresponsive:

  • Session is closed automatically
  • onSessionEnded() is triggered on the receiver side
  • onDisconnected() is triggered on the client

This helps detect network issues or crashed peers without needing manual pings.