type Locality struct {// Region is the region of the xDS client application.Regionstring// Zone is the area within a region.Zonestring// SubZone is the further subdivision within a zone.SubZonestring}

type MetricsReporter interface {// ReportMetric reports a metric. The metric will be one of the predefined// set of types depending on the client (XDSClient or LRSClient).//// Each client will produce different metrics. Please see the client's// documentation for a list of possible metrics events.ReportMetric(metricany)}

type Node struct {// ID is a string identifier of the application.IDstring// Cluster is the name of the cluster the application belongs to.Clusterstring// Locality is the location of the application including region, zone,// sub-zone.LocalityLocality// Metadata provides additional context about the application by associating// arbitrary key-value pairs with it.Metadataany// UserAgentName is the user agent name of application.UserAgentNamestring// UserAgentVersion is the user agent version of application.UserAgentVersionstring}

type ServerIdentifier struct {// ServerURI is the target URI of the server.ServerURIstring// Extensions can be populated with arbitrary data to be passed to the// TransportBuilder and/or xDS Client's ResourceType implementations.// This field can be used to provide additional configuration or context// specific to the user's needs.//// The xDS and LRS clients do not interpret the contents of this field.// It is the responsibility of the user's custom TransportBuilder and/or// ResourceType implementations to handle and interpret these extensions.//// For example, a custom TransportBuilder might use this field to// configure a specific security credentials.//// Extensions may be any type that is comparable, as they are used as map// keys internally. If Extensions are not able to be used as a map key,// the client may panic.//// See:https://go.dev/ref/spec#Comparison_operators//// Any equivalent extensions in all ServerIdentifiers present in a single// client's configuration should have the same value. Not following this// restriction may result in excess resource usage.Extensionsany}

type Stream interface {// Send sends the provided message on the stream.Send([]byte)error// Recv blocks until the next message is received on the stream.Recv() ([]byte,error)}

type Transport interface {// NewStream creates a new streaming call to the server for the specific// RPC method name. The returned Stream interface can be used to send and// receive messages on the stream.NewStream(context.Context,string) (Stream,error)// Close closes the Transport.Close()}

type TransportBuilder interface {// Build creates a new Transport instance to the server based on the// provided ServerIdentifier.Build(serverIdentifierServerIdentifier) (Transport,error)}