> For the complete documentation index, see [llms.txt](/llms.txt)

# GS2-Realtime API Reference

Real-time communication feature




Enables competitive and cooperative play functionality.

When you create a room, three pieces of information, `IP address` `port` `encryption key` will be issued.
To join a room, connect to the issued `IP address` `port` via WebSocket.
The communication is done using the issued `encryption key`.

While GS2 services are generally charged per API request, this service is charged
based on the game server's uptime and the volume of communication.
The number of messages exchanged does not incur a charge.

### Room Lifecycle

#### Created

GS2-Realtime starts the server after receiving a room creation request.
If the number of available rooms falls below a certain threshold, GS2-Realtime starts
additional rooms in bulk to serve as hot standby rooms.

This means that there is a difference in the time between a `cold start', when the server is started after receiving a request, and a `warm start', when a room on hot standby is used.

The estimated waiting time for a cold start is 40 to 60 seconds.
Estimated waiting time for a warm start is 1 to 3 seconds.

#### Exit

The activated room will be terminated if no one comes to connect for 5 minutes after it is created.
This termination process also applies to rooms on hot standby, but the hot standby startup time is not added to the usage fee.

A room will be automatically terminated after one minute of no communication from all players participating in the room.

The maximum startup time for a room is 3 hours. Rooms are automatically terminated after 3 hours of creation.

#### Cold Start Occurrence Conditions

- A start request is issued faster than a hot standby server can be prepared
- The game server is upgraded to a new version
- No hot standby is prepared because start requests are infrequent

[Introduction to Microservices / GS2-Realtime](../../microservices/realtime)



- [GS2-Realtime Deploy/CDK Reference](/api_reference/realtime/deploy/)
  
- [GS2-Realtime SDK API Reference](/api_reference/realtime/sdk/)
  
- [GS2-Realtime SDK for Game Engine API Reference](/api_reference/realtime/game_engine/)