Parse.com

• Cloud for apps
• Several services: Data, Push, Analytics...
• Push: Transaction initiated by the server (≠ Pull)
• Push SDK for iOS, Android, Windows and Windows Phone

• Easy integration e.g. iOS (after having added the dependencies)

  [Parse setApplicationId:@"xxxxx"
                clientKey:@"xxxxx"];
  

in application:didFinishLaunchingWithOptions:

// Register for Push Notitications, if running iOS 8
if ([application respondsToSelector:@selector(registerUserNotificationSettings:)]) {
  UIUserNotificationType userNotificationTypes = (UIUserNotificationTypeAlert |
                                                  UIUserNotificationTypeBadge |
                                                  UIUserNotificationTypeSound);
  UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:userNotificationTypes
                                                                           categories:nil];
  [application registerUserNotificationSettings:settings];
  [application registerForRemoteNotifications];
} else {
  // Register for Push Notifications before iOS 8
  [application registerForRemoteNotificationTypes:    (UIRemoteNotificationTypeBadge |
                                                   UIRemoteNotificationTypeAlert |
                                                   UIRemoteNotificationTypeSound)];
}

in the App main delegate:

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
  // Store the deviceToken in the current installation and save it to Parse.
  PFInstallation *currentInstallation = [PFInstallation currentInstallation];
  [currentInstallation setDeviceTokenFromData:deviceToken];
  [currentInstallation saveInBackground];
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
  [PFPush handlePush:userInfo];
}

• Subscribing to a channel

  PFInstallation *currentInstallation = [PFInstallation currentInstallation];
   [currentInstallation addUniqueObject:[NSString stringWithFormat:@"participant_uuid_%@", userUuid] forKey:@"channels"];
   [currentInstallation saveInBackground];
  

• Sending a push
  Several API : JavaScript, PHP, .NET (including Unity SDK), REST API.
  example:

  curl -X POST -H "X-Parse-Application-xxxxx" -H "X-Parse-REST-API-xxxxx" -H "Content-Type:application/json" -H "Cache-Control:no-cache" -H "Postman-Token:89afd163-f1e6-ac87-1399-0c14250b1989" -d '{"where": {"channels": {...}}' https://api.parse.com/1/push