diff --git a/internal/engineproto/engine.proto b/internal/engineproto/engine.proto
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+++ b/internal/engineproto/engine.proto
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+syntax = "proto3";
+
+package centrifugal.centrifugo.engine;
+
+option go_package = "./;engineproto";
+
+// Controller service defines methods for inter-node communication.
+service Controller {
+  // StreamControlEvents delivers a unidirectional stream of messages from other nodes in
+  // the cluster.
+  rpc StreamControlEvents(StreamControlEventsRequest) returns (stream ControlEvent);
+  // PublishControl sends a control message to other nodes. See PublishControlRequest
+  // for more semantics description.
+  rpc PublishControl(PublishControlRequest) returns (PublishControlResponse);
+}
+
+// Broker service defines methods for PUB/SUB implementation. It can optionally provide
+// history management in channels.
+service Broker {
+  // StreamBrokerEvents delivers a unidirectional stream of broker events to the node.
+  rpc StreamBrokerEvents(StreamBrokerEventsRequest) returns (stream BrokerEvent);
+  // Subscribe to a channel.
+  rpc Subscribe(SubscribeRequest) returns (SubscribeResponse);
+  // Unsubscribe from a channel.
+  rpc Unsubscribe(UnsubscribeRequest) returns (UnsubscribeResponse);
+  // Publish sends data into a channel. See PublishRequest for more semantics description.
+  rpc Publish(PublishRequest) returns (PublishResponse);
+  // PublishJoin sends a Join message into a channel.
+  rpc PublishJoin(PublishJoinRequest) returns (PublishJoinResponse);
+  // PublishLeave sends a Leave message into a channel.
+  rpc PublishLeave(PublishLeaveRequest) returns (PublishLeaveResponse);
+  // History extracts publications from a channel’s history stream.
+  rpc History(HistoryRequest) returns (HistoryResponse);
+  // RemoveHistory removes the history from a channel.
+  rpc RemoveHistory(RemoveHistoryRequest) returns (RemoveHistoryResponse);
+
+  // Below, we also have Controller methods. Generally, these methods are not
+  // required to be implemented if Controller explicitly configured in Centrifugo
+  // (in-memory, Redis-based or Nats-based), or it's a Broker defined for a
+  // channel namespace.
+
+  // StreamControlEvents is the same as Controller.StreamControlEvents.
+  rpc StreamControlEvents(StreamControlEventsRequest) returns (stream ControlEvent);
+  // PublishControl is the same as Controller.PublishControl.
+  rpc PublishControl(PublishControlRequest) returns (PublishControlResponse);
+}
+
+// PresenceManager service is responsible for channel presence management.
+service PresenceManager {
+  // Presence returns full actual presence data for a channel.
+  rpc Presence(PresenceRequest) returns (PresenceResponse);
+  // PresenceStats returns short statistics of current presence data.
+  rpc PresenceStats(PresenceStatsRequest) returns (PresenceStats);
+  // AddPresence sets or updates presence information for a client. This is
+  // called on connection start and periodically for channels with presence on.
+  rpc AddPresence(AddPresenceRequest) returns (AddPresenceResponse);
+  // RemovePresence removes presence information for a client. This is called when
+  // client leaves channel. If this method returns error then request won't
+  // be retried – PresenceManager implementation should detect and eventually
+  // expire stale (not updated) client entries.
+  rpc RemovePresence(RemovePresenceRequest) returns (RemovePresenceResponse);
+}
+
+// ControlEvent represents a control event carrying arbitrary control data.
+message ControlEvent {
+  bytes data = 1;
+}
+
+message StreamControlEventsRequest {
+  // The identifier of current Centrifugo node.
+  string node_id = 1;
+}
+
+// Publication is a data sent to a channel.
+message Publication {
+  // Offset is an incremental position number inside a history stream.
+  uint64 offset = 1;
+  // Data published to a channel.
+  bytes data = 2;
+  // Info is optional information about client connection published with this data.
+  ClientInfo info = 3;
+  // Tags contains a map with custom key-values attached to a Publication.
+  map<string, string> tags = 4;
+  // Time of publication as Unix timestamp in milliseconds.
+  int64 time = 5;
+  // Channel is only set when subscription channel does not match channel in Publication.
+  string channel = 6;
+}
+
+// ClientInfo contains information about a client connection.
+message ClientInfo {
+  // ClientID is a client unique id.
+  string client_id = 1;
+  // UserID is an ID of an authenticated user. Empty means anonymous.
+  string user_id = 2;
+  // ConnInfo is additional information about the connection.
+  bytes conn_info = 3;
+  // ChanInfo is additional information in the context of a channel subscription.
+  bytes chan_info = 4;
+}
+
+// StreamPosition describes a position in a publication history stream.
+message StreamPosition {
+  // Offset defines the publication incremental offset.
+  uint64 offset = 1;
+  // Epoch allows handling situations when the history stream is reset.
+  string epoch = 2;
+}
+
+// HistoryFilter allows filtering history according to the set fields.
+message HistoryFilter {
+  // Since extracts publications from stream starting at the given position.
+  StreamPosition since = 1;
+  // Limit number of publications to return (-1 for no limit, 0 for none).
+  int32 limit = 2;
+  // Reverse direction flag.
+  bool reverse = 3;
+}
+
+// HistoryOptions define fields to alter History method behaviour.
+message HistoryOptions {
+  // Filter for history publications.
+  HistoryFilter filter = 1;
+  // MetaTTL overrides the default history meta information expiration time.
+  int64 meta_ttl = 2;
+}
+
+// PublishOptions define fields to alter the behaviour of the Publish operation.
+message PublishOptions {
+  // history_ttl sets history expiration for inactive streams.
+  int64 history_ttl = 1;
+  // history_size sets a limit on history size.
+  int32 history_size = 2;
+  // history_meta_ttl sets a history meta information expiration time upon publish.
+  int64 history_meta_ttl = 3;
+  // client_info to include into the Publication.
+  ClientInfo client_info = 4;
+  // tags to attach to the Publication.
+  map<string, string> tags = 5;
+  // idempotency_key for idempotent publish.
+  string idempotency_key = 6;
+  // idempotent_result_ttl sets expiration for idempotency results in channel.
+  int64 idempotent_result_ttl = 7;
+  // use_delta is set to true when delta encoding should be used for this publication.
+  bool use_delta = 8;
+}
+
+// PublicationEvent represents an event carrying publication data.
+message PublicationEvent {
+  string channel = 1;
+  Publication publication = 2;
+  StreamPosition stream_position = 3;
+  bool use_delta = 4;
+  Publication previous_publication = 5; // Optional previous publication (if use_delta was true).
+}
+
+// JoinEvent represents an event when a client joins a channel.
+message JoinEvent {
+  string channel = 1;
+  ClientInfo info = 2;
+}
+
+// LeaveEvent represents an event when a client leaves a channel.
+message LeaveEvent {
+  string channel = 1;
+  ClientInfo info = 2;
+}
+
+// BrokerEvent is a wrapper that can carry one of the event types.
+// Should contain ONE OF the defined events. We are not using oneof
+// feature of Protobuf for better interoperability with different
+// systems
+message BrokerEvent {
+  PublicationEvent publication_event = 1;
+  JoinEvent join_event = 2;
+  LeaveEvent leave_event = 3;
+}
+
+message StreamBrokerEventsRequest {}
+
+message SubscribeRequest {
+  string channel = 1;
+}
+
+message SubscribeResponse {
+}
+
+message UnsubscribeRequest {
+  string channel = 1;
+}
+
+message UnsubscribeResponse {
+}
+
+message PublishRequest {
+  // channel to publish to.
+  string channel = 1;
+  // data to publish.
+  bytes data = 2;
+  // various options for publish operation.
+  PublishOptions opts = 3;
+}
+
+message PublishResponse {
+  // StreamPosition describes the stream epoch and offset assigned to the publication.
+  StreamPosition stream_position = 1;
+  // Suppressed indicates if the Publish operation was idempotently suppressed.
+  bool suppressed = 2;
+}
+
+message PublishJoinRequest {
+  string channel = 1;
+  ClientInfo info = 2;
+}
+
+message PublishJoinResponse {}
+
+message PublishLeaveRequest {
+  string channel = 1;
+  ClientInfo info = 2;
+}
+
+message PublishLeaveResponse {}
+
+message PublishControlRequest {
+  // data is a payload set by Centrifuge, it should be delivered untouched to other nodes.
+  bytes data = 1;
+  // If node_id is empty then the message must be delivered to all nodes. If set – only to node with that identifier.
+  string node_id = 2;
+}
+
+message PublishControlResponse {}
+
+message HistoryRequest {
+  string channel = 1;
+  HistoryOptions opts = 2;
+}
+
+message HistoryResponse {
+  repeated Publication publications = 1;
+  // StreamPosition reflects the current history stream top offset and epoch.
+  StreamPosition stream_position = 2;
+}
+
+message RemoveHistoryRequest {
+  string channel = 1;
+}
+
+message RemoveHistoryResponse {}
+
+// ------------------------
+// Presence Manager Messages
+// ------------------------
+
+// PresenceStats represents short presence information for a channel.
+message PresenceStats {
+  int32 num_clients = 1; // Number of client connections.
+  int32 num_users = 2;   // Number of unique users.
+}
+
+// PresenceRequest is used to query full presence data.
+message PresenceRequest {
+  string channel = 1;
+}
+
+// PresenceResponse returns full presence data as a map.
+message PresenceResponse {
+  map<string, ClientInfo> clients = 1;
+}
+
+// PresenceStatsRequest is used to request presence statistics.
+message PresenceStatsRequest {
+  string channel = 1;
+}
+
+// AddPresenceRequest updates or sets presence information.
+message AddPresenceRequest {
+  string channel = 1;
+  string client_id = 2;
+  ClientInfo info = 3;
+}
+
+message AddPresenceResponse {}
+
+// RemovePresenceRequest removes presence information.
+message RemovePresenceRequest {
+  string channel = 1;
+  string client_id = 2;
+  string user_id = 3;
+}
+
+message RemovePresenceResponse {}