POST /v1/universes/{universeId}/topics/{topic} — messaging-service/v1

Publish a cross-server message to a universe

Publish a message to a pre-defined topic of an experience, with the size of the message up to 1,024 characters (1 KB). Requires the Publish permission for API keys and the universe-messaging-service:publish scope for OAuth 2.0 apps. See Cross-server messaging for defining and subscribing users to a topic.

Endpoint

Method: POST

Path: /v1/universes/{universeId}/topics/{topic}

Servers:

https://apis.roblox.com/messaging-service/

Parameters

Name	Location	Required	Description
universeId	path	true	The identifier of the experience in which you want to send your messages to. You can copy your experience's Universe ID on Creator Dashboard.
topic	path	true	The topic that you want to publish your message to, with up to 80 characters.

[
  {
    "name": "universeId",
    "in": "path",
    "required": true,
    "description": "The identifier of the experience in which you want to send your messages to. You can [copy your experience's Universe ID](/cloud/guides/usage-messaging.md#publishing-messages-to-live-servers) on **Creator Dashboard**.",
    "schema": {
      "type": "integer",
      "format": "int64"
    }
  },
  {
    "name": "topic",
    "in": "path",
    "required": true,
    "description": "The topic that you want to publish your message to, with up to 80 characters.",
    "schema": {
      "type": "string",
      "nullable": true
    }
  }
]

Request Body

{
  "content": {
    "application/json-patch+json": {
      "schema": {
        "$ref": "#/components/schemas/PublishRequest"
      }
    },
    "application/json": {
      "schema": {
        "$ref": "#/components/schemas/PublishRequest"
      }
    },
    "text/json": {
      "schema": {
        "$ref": "#/components/schemas/PublishRequest"
      }
    },
    "application/*+json": {
      "schema": {
        "$ref": "#/components/schemas/PublishRequest"
      }
    }
  }
}

Responses

Status	Description
200	Returns an empty response body.
400	Invalid request.
401	The API key is not valid for this operation / You don't have the authorization.
403	Publishing is not allowed on this experience.
500	Server internal error / Unknown error.

{
  "200": {
    "description": "Returns an empty response body."
  },
  "400": {
    "description": "Invalid request."
  },
  "401": {
    "description": "The API key is not valid for this operation / You don't have the authorization."
  },
  "403": {
    "description": "Publishing is not allowed on this experience."
  },
  "500": {
    "description": "Server internal error / Unknown error."
  }
}

Authentication

{
  "security": [
    {
      "roblox-api-key": [
        "universe-messaging-service:publish"
      ]
    },
    {
      "roblox-oauth2": [
        "universe-messaging-service:publish"
      ]
    }
  ],
  "securitySchemes": {
    "roblox-api-key": {
      "type": "apiKey",
      "description": "A configurable key that allows granular access to Roblox resources. See https://create.roblox.com/docs/cloud/auth/api-keys for more information.",
      "in": "header",
      "name": "x-api-key"
    },
    "roblox-oauth2": {
      "type": "oauth2",
      "description": "Build or authorize apps to access Roblox resources. See https://create.roblox.com/docs/cloud/auth/oauth2-overview for more information.",
      "flows": {
        "authorizationCode": {
          "authorizationUrl": "https://apis.roblox.com/oauth/v1/authorize",
          "tokenUrl": "https://apis.roblox.com/oauth/v1/token",
          "refreshUrl": "https://apis.roblox.com/oauth/v1/token",
          "scopes": {
            "universe-messaging-service:publish": "This grants the ability to publish messages on behalf of users."
          }
        }
      }
    }
  }
}

PublishRequest

Complete Operation Definition

{
  "tags": [
    "CrossServerMessaging"
  ],
  "operationId": "CrossServerMessaging_Publish",
  "x-roblox-cloud-api-operation-name": "Publish a Message",
  "x-roblox-stability": "BETA",
  "x-roblox-recommended-alternatives": [
    {
      "url": "https://apis.roblox.com/cloud/v2/universes/{universe_id}:publishMessage",
      "httpMethod": "POST",
      "documentationUrl": "https://create.roblox.com/docs/cloud/reference/features/universes#Cloud_PublishUniverseMessage"
    }
  ],
  "summary": "Publish a cross-server message to a universe",
  "description": "Publish a message to a pre-defined topic of an experience, with the size of the message up to 1,024 characters (1 KB). Requires the **Publish** permission for API keys and the **universe-messaging-service:publish** scope for OAuth 2.0 apps. See [Cross-server messaging](/cloud-services/cross-server-messaging.md#subscribe-users-to-receive-messages) for defining and subscribing users to a topic.",
  "parameters": [
    {
      "name": "universeId",
      "in": "path",
      "required": true,
      "description": "The identifier of the experience in which you want to send your messages to. You can [copy your experience's Universe ID](/cloud/guides/usage-messaging.md#publishing-messages-to-live-servers) on **Creator Dashboard**.",
      "schema": {
        "type": "integer",
        "format": "int64"
      }
    },
    {
      "name": "topic",
      "in": "path",
      "required": true,
      "description": "The topic that you want to publish your message to, with up to 80 characters.",
      "schema": {
        "type": "string",
        "nullable": true
      }
    }
  ],
  "requestBody": {
    "content": {
      "application/json-patch+json": {
        "schema": {
          "$ref": "#/components/schemas/PublishRequest"
        }
      },
      "application/json": {
        "schema": {
          "$ref": "#/components/schemas/PublishRequest"
        }
      },
      "text/json": {
        "schema": {
          "$ref": "#/components/schemas/PublishRequest"
        }
      },
      "application/*+json": {
        "schema": {
          "$ref": "#/components/schemas/PublishRequest"
        }
      }
    }
  },
  "responses": {
    "200": {
      "description": "Returns an empty response body."
    },
    "400": {
      "description": "Invalid request."
    },
    "401": {
      "description": "The API key is not valid for this operation / You don't have the authorization."
    },
    "403": {
      "description": "Publishing is not allowed on this experience."
    },
    "500": {
      "description": "Server internal error / Unknown error."
    }
  },
  "security": [
    {
      "roblox-api-key": [
        "universe-messaging-service:publish"
      ]
    },
    {
      "roblox-oauth2": [
        "universe-messaging-service:publish"
      ]
    }
  ],
  "x-roblox-scopes": [
    {
      "name": "universe-messaging-service:publish"
    }
  ],
  "x-roblox-cloud-api-operation": true
}