Windows Azure Sync Service sample shows you how to extend the reach of your data to anyone that has an Internet connection. This sample shows you how to implement and deploy a Azure Hosted Service to synchronize between a SQL Azure database and a SQL Server Compact database. This allows your users to take data offline and store it in a client database, such as SQL Server Compact, so that your client apps operate while disconnected and your customers can stay productive without the need for a reliable network connection.
The hosted service demonstrated in this sample operates as the middle tier in a 3-tier architecture, and uses Windows Communication Foundation (WCF) to communicate synchronization commands and data between client app and SQL Azure database. The use of a 3-tier architecture means your customers and business partners connect to hosted service and don't connect directly to your SQL Azure database, providing greater flexibility and security.
More Info: Windows Azure Sync Service Demo