Procedure

1. Implement the ISiteSyncSnapIn interface
   In both projects, create a class and name it CustomTypeSiteSyncSnapIn.cs.
   This class must implements the ISiteSyncSnapIn interface.
2. Register the custom items in the Global.asax class
   Open the Global.asax and on Application_Start, attach an EventHandler method to the SystemManager.ApplicationStart event.
   This handler registers your custom items.
   
3. Add the required members of the CustomTypeSiteSyncSnapIn class.
   
4. Subscribe to the Created event.
   This tutorial uses FileSystemWatcher that provides the following file system events: Changed, Deleted, Created, and Renamed.

   To subscribe to the Created event, in the constructor of the CustomTypeSiteSyncSnapIn class, add the App_Data\Sitefinity\Test path that will be watched by the watcher and subscribe to the Created event.

5. Create a SiteSync log entry
   Every time you create a new item inside folder Test, the event handler for the Created event is called. Inside this handler, you must create a site sync log entry for each target server.
   To do this, you use the dataStore object and set the corresponding properties for the log entry.

   RESULT: Every time you create a new folder or file inside the Test folder, a log entry for the created item is logged in the database.

   NOTE: Immediately after you create a new folder or file, the event is raised. It gets the first (default) name of the item. Therefore, if you want to change the default name of the item, you must implement an event handler for the Renamed event of the FileSystemWatcher class.

6. Implement the methods of the ISiteSyncSnapIn interface.
   You implement the following methods:
   
   • GetPendingItems
     This method returns the items that are pending for synchronization for the current type.
     
   • GetExportItemsCount
     This is a method that you implement for your custom snap-in. It gives you the number of the items that you have checked for export.
     Inside this method, you call GetExportItems, which gets only the items that you have checked for syncing.
     
   • Export
     This method is the method that exports the items for syncing.
     Inside this method, you go through the log entries that are check for synchronization for the current type. For every log entry, you create a WrapperObject that you add to the export transaction. In this object, you can add properties and their values. You can also give an object with properties to the constructor of the Wrapper object. With the CommonItemLoader you can set the common properties for the log entry.
     In the export transaction, you set the header for the current site sync snap-in and in the export transaction items you add the wrapper objects.

     NOTE: You can choose how you want to export the items – all items in one transaction, or a separate transaction for each entry.

7. Save the items on the target server
   You must also implement the logic for saving the items on the target server. For each exported transaction from the Export method, you must implement an Import method. It takes as parameter the current transaction with the exported items.