Websockets: Data Design Patterns

I'm looking for some help with best practices and standards for my first Websockets chat app. I don't have any reference for this– so this is what I have currently implemented. There are many types of Messages that can be sent in this service:

• Text Messages
• Video Messages
• Image Messages
... etc

So imagine chatrooms that multiple people can be in. Here is how I am thinking about sending messages from the client to server:

{
  "type": "room.message",
  "data": {
    "meta": {
      "color": "#FFFFFF"
    },
    "message": "Hello, how are you?"
  }
}

This is the design for the message being sent down from the server to the clients connected to the room.

{
  "type": "room.message_broadcast",
  "data": {
    "meta": {
      "color": "#FFFFFF"
    },
    "message": "Hello, how are you?",
    "user": userObject
  }
}

From a best practices standpoint, does it make sense to follow this type and type_broadcast format? Following on from that, does it make sense how I'm structuring the interior data structure regarding type and data? Following this same pattern, we would do this for images:

{
  "type": "room.image",
  "data": {
    "url": "https://www.google.com/someimage.png"
  }
}

{
  "type": "room.image_broadcast",
  "data": {
    "url": "https://www.google.com/someimage.png"
    "user": userObject
  }
}

From a design perspective, does this pattern make sense for a realtime chat room with multiple types?