Sync Framework can be installed by using the Install SQL Server 2008 wizard or by using command line installation options. To install Sync Framework by using the wizard, on the Feature Selection page, select Microsoft Sync Framework. For more information about how to install SQL Server and related components, see Overview of SQL Server Installation.

The ability to support mobile and remote workers is becoming more important for organizations every day. It is very important for organizations to make sure that workers have access to the same information that they have when they are in the office. In most cases, these users will have a laptop, office desktop, smartphone, or PDA. From these devices, users can often access their data directly by using a VPN connection or some other method of connecting directly to the corporate network. For most remote users, this solution is less than satisfactory because of major disadvantages in the following areas:

• Network requirements
  To enable users to access information, the remote device must have a constant connection to the corporate network while it is accessing data. For some workers, such as those who are working from home, this might not be a problem. For others, such as salespeople who are constantly on the move, this could be more difficult. For example, if a salesperson is visiting a customer and cannot access inventory data because there is no network connectivity, the salesperson cannot effectively do her job.
  
• Data access speeds
  In a typical client/server corporate environment, users have high speed networks that enable quick access to information. However, remote workers are usually connected over slow, unreliable wired or wireless networks. By using a typical solution, every piece of data that a user wants must be downloaded every time it is requested because there is no way to persist the data on the device. For example, if a salesperson must download his product list every time he opens his application, the time lag required to populate the application with information could be frustrating.
  
• Single point of failure
  With this kind of solution, all users rely on a single server. If that database is not available because of planned server downtime or from server failures, all remote workers will be disconnected from their data.
  
• Server scalability
  As more people work remotely, the performance of the corporate servers will be affected, and more hardware might have to be added.
  

Occasionally Connected Applications

Sync Services for ADO.NET enables synchronization between databases. It provides an intuitive and flexible API that enables you to build applications that target offline and collaboration scenarios. Sync Services for ADO.NET enables synchronization between two peers, such as SQL Server databases or between a SQL Server Compact 3.5 client database and any server database for which an ADO.NET provider is available. The API enables you to use all or only some of the components that are provided, depending on the architecture and requirements of an application.

The following illustrations show examples of occasionally connected applications in which data (represented by a green database) is persisted locally on the device of a remote worker. The first example shows a stand-alone database system in which information is stored directly on the user’s device. The second example shows a remote office where information is stored in a workgroup database within this remote office so that multiple local workers can access the data.

A common extension to this type of occasionally connected application is the ability to support collaboration scenarios. These are scenarios in which two databases can be synchronized peer-to-peer without having to go through a central hub. As shown in the following illustration, a remote database is free to exchange information with any other database. This type of solution is useful when remote workers (such as on-site financial auditors) work as a group in a remote location. These workers must often share information amongst each other. However, because they do not have connectivity to the central database, they must share information through some kind of peer-to-peer network.

Sync Services for ADO.NET supports databases in the following ways:

• In offline scenarios, the client database must be SQL Server Compact 3.5 version 3.5 or later. The server can be any database for which an ADO.NET provider is available.
  
• In collaborative scenarios, each peer database must be SQL Server 2000 Service Pack 4 or a later version.
  

SQL Server is an enterprise-class database that provides a solid foundation for applications that require synchronization. SQL Server 2008 provides change tracking, one of the most useful features for synchronization developers. Sync Services for ADO.NET provides an API to synchronize changes, but it does not actually track changes in the server or peer database. (SQL Server Compact 3.5 does track changes in the client database.) You can create a custom change tracking system, but this typically introduces significant complexity and performance overhead. We recommend that you use change tracking in SQL Server 2008, because it is easy to configure and provides high performance tracking. For more information, see Tracking Data Changes.

Microsoft offers several technologies that are designed for applications that perform synchronization. Therefore, it is useful to compare Sync Services for ADO.NET to other technologies that are used in offline and collaborative scenarios.

Offline Synchronization

Collaborative Synchronization

Deciding Which Technology to Use

Concepts

Help and Information