event

type Event struct {

	// Topic is the topic to which this event is published
	Topic types.Path

	// Type of the event. This is usually used as a hint to what struct types to use to unmarshal data
	Type Type `json:",omitempty"`

	// ID is unique id for the event.
	ID string

	// Timestamp is the time.UnixNano() value -- this is the timestamp when event occurred
	Timestamp time.Time

	// Received is the timestamp when the message is received.
	Received time.Time `json:",omitempty"`

	// Data contains some application specific payload
	Data *types.Any `json:",omitempty"`

	// Error contains any errors that occurred during delivery of the mesasge
	Error error `json:",omitempty"`
}

type Plugin interface {

	// List returns a list of *child nodes* given a path for a topic.
	// A topic of "." is the top level
	List(topic types.Path) (child []string, err error)
}

type Publisher interface {

	// PublishOn sets the channel to publish.  Note that the implementation is given a channel
	// to publish on.  This is so that the server can optionally add buffering without the
	// implementations having any knowledge.
	PublishOn(chan<- *Event)
}

type Subscriber interface {

	// SubscribeOn returns the channel for the topic
	SubscribeOn(topic types.Path) (<-chan *Event, chan<- struct{}, error)
}

type Type string

type Validator interface {

	// Validate validates the topic
	Validate(topic types.Path) error
}