Client and Server Environments
Microsoft® SQL Server™ 2000 Windows® CE Edition (SQL Server CE) relies on several components to exchange data from a Microsoft Windows CE-based device to an instance of SQL Server. The following illustration shows the relationship between the different components.
SQL Server CE Database Engine
The SQL Server CE database engine manages the SQL Server data store on the Windows CE-based device. The SQL Server CE database engine can track all database records that are inserted, updated, or deleted by maintaining a small amount of change tracking information with each record. The tracking functionality is enabled when you use one of the two connectivity solutions.
SQL Server CE Client Agent
The SQL Server CE Client Agent is the primary component for connectivity on the Windows CE-based device. It implements these custom SQL Server CE objects: the Replication object, Remote Data Access (RDA) object, and Engine object. By using these objects, applications can programmatically control connections to SQL Server.
SQL Server CE Server Agent
The SQL Server CE Server Agent handles the HTTP requests made by the SQL Server CE Client Agent. When an application makes a request, the SQL Server CE Client Agent sends the request to the SQL Server CE Server Agent through HTTP. The SQL Server CE Server Agent connects to SQL Server and returns the resulting recordset to the SQL Server CE Client Agent through HTTP. Additional SQL Server connectivity components are involved in this process and are also located on the computer running Microsoft Internet Information Services (IIS), although they are not shown in the preceding illustration.
Replication and RDA handle HTTP requests differently and use different SQL Server connectivity components on the computer running IIS. For more information, see Managing Connectivity.
Supported Connectivity Solutions
SQL Server CE connectivity solutions communicate using Web protocols, HTTP or HTTPS. The SQL Server CE Client Agent, which resides on the Windows CE-based device, uses HTTP(S) to communicate with the SQL Server CE Server Agent on the Web server. The SQL Server CE Server Agent, which resides on the computer running IIS, communicates with SQL Server using either replication or remote data access.
Note SQL Server CE connectivity solutions are primarily intended for Windows CE-based devices that are occasionally connected to the network.
SQL Server CE works with the following network connectivity as long as they are configured to support HTTP(S):
- Wireless LANs
- Wireless WANs
By using Microsoft ActiveSync® 3.5 and a Pocket PC 2002 device connected using serial, infrared, or USB, you can directly access SQL Server through the network connection of the desktop computer. Other device and ActiveSync combinations require SQL Server CE Relay to be configured on the desktop computer.
SQL Server CE can use the Secure Sockets Layer (SSL) feature of IIS to encrypt data propagated between the device running SQL Server CE and the computer running SQL Server.
In addition, SQL Server CE connectivity solutions optimize wireless communication by compressing data to minimize the amount of data sent over the network. Data is propagated between the Windows CE-based device and the server by using a simple protocol patterned after file transfer protocols. SQL Server CE connectivity solutions recover from communication failures by restarting from the last successfully transmitted block of data, as long as the connection recovers within a time-out period of approximately two minutes. This makes synchronization possible even if the underlying transport is not reliable.