Proposal: handle onMessage by message type

This would be a big breaking change, I’d like to know your thoughts and opinions about this. Will it be valuable/worth doing? Feedback is highly appreciated!

Server-side

client.send() to replace this.send() + message type:

// new
client.send("skill", { name: "fireball" })

// deprecate
this.send(client, { type: "skill", name: "fireball" }

client.send() a schema-encoded message

This is already supported by the server-side. See below plans to support this from client-side as well.

class SkillMessage extends Schema {
  @type("string") name: string;
}

const skill = new SkillMessage();
skill.name = "fireball";
client.send(skill);

Broadcast with type + data

// new
this.broadcast("skill", { name: "fireball" })

// deprecate
this.broadcast({ type: "skill", name: "fireball" })

onMessage to handle messages sent from the clients

// new
onCreate() {
    this.onMessage("move", (client, message) => {
        // handle "move" message
    });

    this.onMessage(MoveMessage, (client, message) => {
        // handle schema-encoded "SchemaMessage"
        // (get autocompletion for "message")
    });
}

// deprecate
onMessage(client, message) {
}

Client-side

Allow sending the type of a message along with its data:

// new
room.send("move", { angle: 270 });

// deprecate
room.send({ type: "move", angle: 170 });

Allow sending a Schema structure from the client-side (this will be specially useful for strongly-typed languages, such as C#, C++, etc.)

class MoveMessage extends Schema {
    @type("number") angle: number;
}

const message = new MoveMessage();
message.angle = 170;

room.send(message);

Receiving messages by type:

// new
room.onMessage("skill", (message) => {
  // handle "skill" message
});

room.onMessage(SkillMessage, (message) => {
  // handle schema-encoded "skill" message
});

// deprecate
room.onMessage((message) => {
  // handle any type of message
});

---

As always suggestions are welcome.

[stats]

I like this change.

[zgz682000]

It sounds like an amazing change, and I would more like to use Schema instead of Fossil Delta. Why I choose Fossil Delta but not Schema? Because the schema code generator is not customable. Would you consider to implement the generator by template mechanism？