Represents a request to reserve a client ID and return it. Client IDs are
unique only in the context of a room.
Represents a connection from a service to a client, which consists of a
message receiver and a user ID.
Represents a message sent to one or more clients from the server.
Actor model representation of a “room”. A room is a set of clients
that share an instance of a Stateroom instance. Conceptually, this
is like a room in a chat service. Events (such as messages) and their
side-effects are isolated to the room in which they occur.
Settings used by the server.