RPC Protocol

{ 
	headers: {
		id:        <message_id>,
		apiKey:    <apid_key>,
		signature: <signature>
	},
	url:      <function_url>  //[required]  
	method:   <http_method>,  //[optional]   
	body:     <param_array>   //[optional]
} 

If body is populated in request, the params list in URL is ignored

{
	cmd:      'pub',     
	mq:       <mq_name>,   //which MQ is the RPC based
	ack:      false        //No ACK from zbus for RPC
}

{
	status:      200|400|403|404|500   //required
	body:        <data_or_exception>,
	id:          <message_id>
}