MessagingService
CreatorHub

Allows servers of the same experience to communicate with each other.

Its interface does not cross the network boundary.

Instances of this class cannot be created with Instance.new.

It is a singleton that may be acquired with GetService.

Memory category	Instances

Tags: [NotCreatable, Service, NotReplicated]

Member index 2

History		Member
573		PublishAsync(topic: string, message: Variant): null
462		SubscribeAsync(topic: string, callback: Function): RBXScriptConnection
63 members inherited from Instance
553		Archivable: bool
553		Attributes: string
553		AttributesReplicate: string
553		AttributesSerialize: BinaryString
635		Capabilities: SecurityCapabilities
553		DataCost: int
619		DefinesCapabilities: bool
553		HistoryId: UniqueId
553		Name: string
553		Parent: Instance
553		PropertyStatusStudio: PropertyStatus
553		RobloxLocked: bool
635		Sandboxed: bool
616		SourceAssetId: int64
553		Tags: BinaryString
616		UniqueId: UniqueId
553		archivable: bool
553		numExpectedDirectChildren: int
576		AddTag(tag: string): null
573		ClearAllChildren(): null
462		Clone(): Instance
573		Destroy(): null
486		FindFirstAncestor(name: string): Instance
486		FindFirstAncestorOfClass(className: string): Instance
486		FindFirstAncestorWhichIsA(className: string): Instance
486		FindFirstChild(name: string, recursive: bool = false): Instance
486		FindFirstChildOfClass(className: string): Instance
486		FindFirstChildWhichIsA(className: string, recursive: bool = false): Instance
486		FindFirstDescendant(name: string): Instance
563		GetActor(): Actor
486		GetAttribute(attribute: string): Variant
462		GetAttributeChangedSignal(attribute: string): RBXScriptSignal
631		GetAttributes(): Dictionary
648		GetChildren(): Instances
462		GetDebugId(scopeLength: int = 4): string
486		GetDescendants(): Array
486		GetFullName(): string
641		GetStyled(name: string): Variant
576		GetTags(): Array
576		HasTag(tag: string): bool
486		IsAncestorOf(descendant: Instance): bool
486		IsDescendantOf(ancestor: Instance): bool
580		IsPropertyModified(name: string): bool
573		Remove(): null
576		RemoveTag(tag: string): null
580		ResetPropertyToDefault(name: string): null
573		SetAttribute(attribute: string, value: Variant): null
462		WaitForChild(childName: string, timeOut: double): Instance
648		children(): Instances
553		clone(): Instance
573		destroy(): null
553		findFirstChild(name: string, recursive: bool = false): Instance
648		getChildren(): Instances
553		isDescendantOf(ancestor: Instance): bool
573		remove(): null
462		AncestryChanged(child: Instance, parent: Instance)
462		AttributeChanged(attribute: string)
462		ChildAdded(child: Instance)
462		ChildRemoved(child: Instance)
462		DescendantAdded(descendant: Instance)
462		DescendantRemoving(descendant: Instance)
500		Destroying()
553		childAdded(child: Instance)
6 members inherited from Object
647		ClassName: string
647		className: string
647		GetPropertyChangedSignal(property: string): RBXScriptSignal
647		IsA(className: string): bool
650		isA(className: string): bool
647		Changed(property: string)

Description

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.

Limit	Maximum
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

History 6
Hide member changes

573 Change ReturnType of PublishAsync from void to null
462 Change ThreadSafety of SubscribeAsync from to Unsafe
462 Change ThreadSafety of PublishAsync from to Unsafe
367 Add SubscribeAsync
367 Add PublishAsync
367 Add MessagingService

Members 2

PublishAsync
CreatorHub

Parameters (2)
topic	string
message	Variant
Returns (1)
null

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.

It will block the calling thread until completion.

Thread safety	Unsafe

History 3

573 Change ReturnType of PublishAsync from void to null
462 Change ThreadSafety of PublishAsync from to Unsafe
367 Add PublishAsync

Tags: [Yields]

SubscribeAsync
CreatorHub

Parameters (2)
topic	string
callback	Function
Returns (1)
RBXScriptConnection

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:

Field	Summary
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.