hub

type Client struct {
	Hub         *Hub
	Name        string       //for filtering who to send messages to
	Send        chan Message // for outbound messages to client
	Topic       string       // message broadcast scope is restricted to a single topic
	Done        chan struct{}
	ConnectedAt time.Time
}

type ClientReport struct {
	Topic       string `json:"topic"`
	ConnectedAt string `json:"connected"`
}

type Hub struct {
	// Registered clients.
	Clients map[string]map[*Client]bool

	// Inbound messages from the clients.
	Broadcast chan Message

	// Register requests from the clients.
	Register chan *Client

	// Unregister requests from clients.
	Unregister chan *Client
}

type Message struct {
	Data   []byte //text data are converted to/from bytes as needed
	Sender Client
	Sent   time.Time //when sent
	Type   int
}