# Messaging API
## Publish Message
Publish a message to a Roblox experience. This takes a message and a topic and publishes the message. Experiences can use the [`MessagingService`](https://create.roblox.com/docs/reference/engine/classes/MessagingService) to subscribe to a topic and listen for messages.
```
USAGE:
rbxcloud messaging publish --topic <TOPIC> --message <MESSAGE> --universe-id <UNIVERSE_ID> --api-key <API_KEY>
OPTIONS:
-a, --api-key <API_KEY> Roblox Open Cloud API Key [env: RBXCLOUD_API_KEY=]
-h, --help Print help information
-m, --message <MESSAGE> Message to send
-t, --topic <TOPIC> Message topic
```
Example:
```
$ rbxcloud messaging publish -t Hello -m "Hello world!" -p 12345 -u 98765 -a MY_KEY
```
```lua
MessagingService:SubscribeAsync("Hello", function(message)
print(message)
--> {message: "Hello world!"}
end)
```