--- /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 FIRMessagingPersistentSyncMessage;
+
+// table data handlers
+/**
+ * Handle message stored in the outgoing RMQ messages table.
+ *
+ * @param rmqId The rmqID of the message.
+ * @param tag The message tag.
+ * @param data The data stored in the message.
+ */
+typedef void(^FCMOutgoingRmqMessagesTableHandler)(int64_t rmqId, int8_t tag, NSData *data);
+
+/// Outgoing messages RMQ table
+extern NSString *const kTableOutgoingRmqMessages;
+/// Server to device RMQ table
+extern NSString *const kTableS2DRmqIds;
+
+@interface FIRMessagingRmq2PersistentStore : NSObject
+
+/**
+ * Initialize and open the RMQ database on the client.
+ *
+ * @param databaseName The name for RMQ database.
+ *
+ * @return A store used to persist messages on the client.
+ */
+- (instancetype)initWithDatabaseName:(NSString *)databaseName;
+
+/**
+ * Save outgoing message in RMQ.
+ *
+ * @param rmqId The rmqID for the message.
+ * @param tag The tag of the message proto.
+ * @param data The data being sent in the message.
+ * @param error The error if any while saving the message to the persistent store.
+ *
+ * @return YES if the message was successfully saved to the persistent store else NO.
+ */
+- (BOOL)saveMessageWithRmqId:(int64_t)rmqId
+ tag:(int8_t)tag
+ data:(NSData *)data
+ error:(NSError **)error;
+
+/**
+ * Add unacked server to device message with a given rmqID to the persistent store.
+ *
+ * @param rmqId The rmqID of the message that was not acked by the cient.
+ *
+ * @return YES if the save was successful else NO.
+ */
+- (BOOL)saveUnackedS2dMessageWithRmqId:(NSString *)rmqId;
+
+/**
+ * Update the last RMQ ID that was sent by the client.
+ *
+ * @param rmqID The latest rmqID sent by the device.
+ *
+ * @return YES if the last rmqID was successfully saved else NO.
+ */
+- (BOOL)updateLastOutgoingRmqId:(int64_t)rmqID;
+
+#pragma mark - Query
+
+/**
+ * Query the highest rmqID saved in the Outgoing messages table.
+ *
+ * @return The highest rmqID amongst all the messages in the Outgoing RMQ table. If no message
+ * was ever persisted return 0.
+ */
+- (int64_t)queryHighestRmqId;
+
+/**
+ * The last rmqID that was saved on the client.
+ *
+ * @return The last rmqID that was saved. If no rmqID was ever persisted return 0.
+ */
+- (int64_t)queryLastRmqId;
+
+/**
+ * Get a list of all unacked server to device messages stored on the client.
+ *
+ * @return List of all unacked s2d messages in the persistent store.
+ */
+- (NSArray *)unackedS2dRmqIds;
+
+/**
+ * Iterate over all outgoing messages in the RMQ table.
+ *
+ * @param handler The handler invoked with each message in the outgoing RMQ table.
+ */
+- (void)scanOutgoingRmqMessagesWithHandler:(FCMOutgoingRmqMessagesTableHandler)handler;
+
+#pragma mark - Delete
+
+/**
+ * Delete messages with given rmqID's from a table.
+ *
+ * @param tableName The table name from which to delete the rmq messages.
+ * @param rmqIds The rmqID's of the messages to be deleted.
+ *
+ * @return The number of messages that were successfully deleted.
+ */
+- (int)deleteMessagesFromTable:(NSString *)tableName
+ withRmqIds:(NSArray *)rmqIds;
+
+/**
+ * Remove database from the device.
+ *
+ * @param dbName The database name to be deleted.
+ */
++ (void)removeDatabase:(NSString *)dbName;
+
+#pragma mark - Sync Messages
+
+/**
+ * Save sync message to persistent store to check for duplicates.
+ *
+ * @param rmqID The rmqID of the message to save.
+ * @param expirationTime The expiration time of the message to save.
+ * @param apnsReceived YES if the message was received via APNS else NO.
+ * @param mcsReceived YES if the message was received via MCS else NO.
+ * @param error The error if any while saving the message to store.
+ *
+ * @return YES if the message was saved successfully else NO.
+ */
+- (BOOL)saveSyncMessageWithRmqID:(NSString *)rmqID
+ expirationTime:(int64_t)expirationTime
+ apnsReceived:(BOOL)apnsReceived
+ mcsReceived:(BOOL)mcsReceived
+ error:(NSError **)error;
+
+/**
+ * Update sync message received via APNS.
+ *
+ * @param rmqID The rmqID of the sync message.
+ * @param error The error if any while updating the sync message in persistence.
+ *
+ * @return YES if the update was successful else NO.
+ */
+- (BOOL)updateSyncMessageViaAPNSWithRmqID:(NSString *)rmqID
+ error:(NSError **)error;
+
+/**
+ * Update sync message received via MCS.
+ *
+ * @param rmqID The rmqID of the sync message.
+ * @param error The error if any while updating the sync message in persistence.
+ *
+ * @return YES if the update was successful else NO.
+ */
+- (BOOL)updateSyncMessageViaMCSWithRmqID:(NSString *)rmqID
+ error:(NSError **)error;
+
+/**
+ * Query sync message table for a given rmqID.
+ *
+ * @param rmqID The rmqID to search for in SYNC_RMQ.
+ *
+ * @return The sync message that was persisted with `rmqID`. If no such message was persisted
+ * return nil.
+ */
+- (FIRMessagingPersistentSyncMessage *)querySyncMessageWithRmqID:(NSString *)rmqID;
+
+/**
+ * Delete sync message with rmqID.
+ *
+ * @param rmqID The rmqID of the message to delete.
+ *
+ * @return YES if a sync message with rmqID was found and deleted successfully else NO.
+ */
+- (BOOL)deleteSyncMessageWithRmqID:(NSString *)rmqID;
+
+/**
+ * Delete the expired sync messages from persisten store. Also deletes messages that have been
+ * delivered both via APNS and MCS.
+ *
+ * @param error The error if any while deleting the messages.
+ *
+ * @return The total number of messages that were deleted from the persistent store.
+ */
+- (int)deleteExpiredOrFinishedSyncMessages:(NSError **)error;
+
+@end