--- /dev/null
+/*
+ * Copyright 2017 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import <Foundation/Foundation.h>
+
+@class GtalkDataMessageStanza;
+
+@class FIRMessagingClient;
+@class FIRMessagingConnection;
+@class FIRMessagingReceiver;
+@class FIRMessagingRmqManager;
+@class FIRMessagingSyncMessageManager;
+
+@protocol FIRMessagingDataMessageManagerDelegate <NSObject>
+
+#pragma mark - Downstream Callbacks
+
+/**
+ * Invoked when FIRMessaging receives a downstream message via the MCS connection.
+ * Let's the user know that they have received a new message by invoking the
+ * App's remoteNotification callback.
+ *
+ * @param message The downstream message received by the MCS connection.
+ */
+- (void)didReceiveMessage:(nonnull NSDictionary *)message
+ withIdentifier:(nullable NSString *)messageID;
+
+#pragma mark - Upstream Callbacks
+
+/**
+ * Notify the app that FIRMessaging will soon be sending the upstream message requested by the app.
+ *
+ * @param messageID The messageId passed in by the app to track this particular message.
+ * @param error The error in case FIRMessaging cannot send the message upstream.
+ */
+- (void)willSendDataMessageWithID:(nullable NSString *)messageID error:(nullable NSError *)error;
+
+/**
+ * Notify the app that FIRMessaging did successfully send it's message via the MCS
+ * connection and the message was successfully delivered.
+ *
+ * @param messageId The messageId passed in by the app to track this particular
+ * message.
+ */
+- (void)didSendDataMessageWithID:(nonnull NSString *)messageId;
+
+#pragma mark - Server Callbacks
+
+/**
+ * Notify the app that FIRMessaging server deleted some messages which exceeded storage limits. This
+ * indicates the "deleted_messages" message type we received from the server.
+ */
+- (void)didDeleteMessagesOnServer;
+
+@end
+
+/**
+ * This manages all of the data messages being sent by the client and also the messages that
+ * were received from the server.
+ */
+@interface FIRMessagingDataMessageManager : NSObject
+
+NS_ASSUME_NONNULL_BEGIN
+
+- (instancetype)initWithDelegate:(id<FIRMessagingDataMessageManagerDelegate>)delegate
+ client:(FIRMessagingClient *)client
+ rmq2Manager:(FIRMessagingRmqManager *)rmq2Manager
+ syncMessageManager:(FIRMessagingSyncMessageManager *)syncMessageManager;
+
+- (void)setDeviceAuthID:(NSString *)deviceAuthID secretToken:(NSString *)secretToken;
+
+- (void)refreshDelayedMessages;
+
+#pragma mark - Receive
+
+- (nullable NSDictionary *)processPacket:(GtalkDataMessageStanza *)packet;
+- (void)didReceiveParsedMessage:(NSDictionary *)message;
+
+#pragma mark - Send
+
+- (void)sendDataMessageStanza:(NSMutableDictionary *)dataMessage;
+- (void)didSendDataMessageStanza:(GtalkDataMessageStanza *)message;
+
+- (void)resendMessagesWithConnection:(FIRMessagingConnection *)connection;
+
+NS_ASSUME_NONNULL_END
+
+@end