service

type Accessor interface {
	Get([]byte) (string, error)
}

type AccessorFactory interface {
	// New creates an Accessor using a slice of endpoints.  Each endpoint must
	// be of the form parseable by ParseHostPort.  Invalid endpoints are skipped
	// with an error log message.  The returned slice of strings is the sorted
	// list of base URLs added to the Accessor.
	New([]string) (Accessor, []string)
}

type AccessorSubscription interface {
	Accessor

	// Cancel removes this subscription from the underlying infrastructure.  No further
	// updates will occur, but this subscription's state will still be usable.
	// This method is idempotent.
	Cancel()
}

type Options struct {
	// Logger is used by any component configured via this Options.  If unset, a default
	// logger is used.
	Logger logging.Logger `json:"-"`

	// Connection is the comma-delimited Zookeeper connection string.  Both this and
	// Servers may be set, and they will be merged together when connecting to Zookeeper.
	Connection string `json:"connection,omitempty"`

	// Servers is the array of Zookeeper servers.  Both this and Connection may be set,
	// and they will be merged together when connecting to Zookeeper.
	Servers []string `json:"servers,omitempty"`

	// Timeout is the Zookeeper connection timeout.
	Timeout time.Duration `json:"timeout"`

	// BaseDirectory is the base path for all znodes created via this Options.
	BaseDirectory string `json:"baseDirectory,omitempty"`

	// MemberPrefix is the prefix for ephemeral nodes regstered via this Options.
	MemberPrefix string `json:"memberPrefix,omitempty"`

	// Environment is the environment component of the ephemeral znode path.
	Environment string `json:"environment,omitempty"`

	// ServiceName is the name of the service being registered.
	ServiceName string `json:"serviceName,omitempty"`

	// Registrations holds the slice of information used to register endpoints.  Typically,
	// this slice will either (1) be empty for an application that only watches for changes,  or (2) have the single
	// Registration indicating how this service is known.  Multiple registrations, essentially
	// being aliases for the same application, are supported.
	Registrations []string `json:"registrations,omitempty"`

	// VnodeCount is used to tune the underlying consistent hash algorithm for servers.
	VnodeCount uint `json:"vnodeCount"`

	// PingFunc is the callback function used to determine if this application is still able
	// to respond to requests.  This can be nil, and there is no default.
	PingFunc func() error `json:"-"`
}

type Registrar interface {
	RegisterEndpoint(string, int, func() error) (*serversets.Endpoint, error)
}

type RegistrarWatcher interface {
	Registrar
	Watcher
}

type Watch interface {
	IsClosed() bool
	Event() <-chan struct{}
	Endpoints() []string
}

type Watcher interface {
	Watch() (*serversets.Watch, error)
}