Synchronizing Data

Microsoft Windows CE Services includes Microsoft® ActiveSync™, which allows you to synchronize, or coordinate, data stored on a Windows-based desktop computer with data stored on a Windows CE–based device. ActiveSync also enables you to coordinate device data with two or more computers or synchronize information on one computer with several devices.

Note ActiveSync does not support synchronization between two devices, a device and a server, or a device and mounted volumes.

Through serial, infrared, Ethernet LAN, or modem connections, the synchronization process automatically transfers and tracks data changes, including additions, deletions, and other revisions to information. As a result, shared information is always up to date and accurate. ActiveSync is a client/server architecture that consists of a service manager (the server) and a service provider (the client):

• The service manager, which is built into Windows CE Services, is a synchronization engine that resides on both the desktop and the device. The service manager performs many common synchronization tasks, which include providing connectivity, detecting changes in data, resolving data conflicts, as well as mapping and transferring data objects.
• The service provider comprises two modules, which typically are dynamic-link libraries (DLLs), that you must implement in your application to perform the synchronization tasks that are specific to your data. One module, called the desktop provider module, resides on the desktop and the other module, called the device provider module, resides on the device.

The service provider interfaces with both the service manager and the application, thereby exposing the application and the application's data to the service manager. In turn, this interaction enables the service manager to synchronize different types of data from different types of applications. The service provider also facilitates all requests made by the service manager, such as displaying a user interface (UI) or reporting status.

Creating a service provider is a two-part process:

1. Create the service provider by developing the desktop provider module and the device provider module.
2. Register the service provider on both the Windows-based computer and the Windows CE–based device.

The service manager implements a single interface, IReplNotify, which is built into ActiveSync and Windows CE Services. Thus, once you register the service provider, the synchronization process is automatic. The service manager, with the help of the service provider, directs and controls all synchronization tasks.

The following illustration shows how the service manager interfaces with the service provider to access data.