Engine

MessagingService

Show Deprecated
not creatable
service
not replicated

MessagingService allows servers of the same experience to communicate with each other in real time (less than 1 second) using topics. Topics are developer‑defined strings (1–80 characters) that servers use to send and receive messages.

Delivery is best effort and not guaranteed. Make sure to architect your experience so delivery failures are not critical.

Cross-Server Messaging explores how to communicate between servers in greater detail.

If you want to publish ad-hoc messages to live game servers, you can use the Open Cloud APIs.

Limitations

Note that these limits are subject to change.

LimitMaximum
Size of message 1kB
Messages sent per game server 600 + 240 * (number of players in this game server) per minute
Messages received per topic (40 + 80 * number of servers) per minute
Messages received for entire game (400 + 200 * number of servers) per minute
Subscriptions allowed per game server 20 + 8 * (number of players in this game server)
Subscribe requests per game server 240 requests per minute

Summary

Methods

Properties

Methods

PublishAsync

void
yields

This function sends the provided message to all subscribers to the topic, triggering their registered callbacks to be invoked.

Yields until the message is received by the backend.

Parameters

topic: string

Determines where the message is sent.

message: Variant

The data to include in the message.


Returns

void

SubscribeAsync

yields

This function registers a callback to begin listening to the given topic. The callback is invoked when a topic receives a message. It can be called multiple times for the same topic.

Callback

The callback is invoked with a single argument, a table with the following entries:

FieldSummary
Data Developer supplied payload
Sent Unix time in seconds at which the message was sent

It yields until the subscription is properly registered and returns a connection object.

To unsubscribe, call Disconnect() on the returned object. Once called, the callback should never be invoked. Killing the script containing the connections also causes the underlying connect to be unsubscribed.

See also MessagingService:PublishAsync() which sends the provided message to all subscribers to the topic, triggering their registered callbacks to be invoked.

Parameters

topic: string

Determines where to listen for messages.

callback: function

Function to be invoked whenever a message is received.


Returns

Connection that can be used to unsubscribe from the topic.

Code Samples

Subscribing to Cross Server Messages

local MessagingService = game:GetService("MessagingService")
local Players = game:GetService("Players")
local function onPlayerAdded(player)
--subscribe to the topic
local topic = "player-" .. player.UserId
local connection = MessagingService:SubscribeAsync(topic, function(message)
print("Received message for", player.Name, message.Data)
end)
player.AncestryChanged:Connect(function()
-- unsubscribe from the topic
connection:Disconnect()
end)
end
Players.PlayerAdded:Connect(onPlayerAdded)

Events