Remote Data Service (RDS) provides a way to easily perform data access in a three-tier client/server system. A client data control specifies connect and command string parameters to perform a query on a remote data source, or connect string and Recordset object parameters to perform an update.
The parameters are passed to a server program, which actually performs the data-access operation on the remote data source. RDS provides a default server program called the RDSServer.DataFactory object. The RDSServer.DataFactory object returns any Recordset object produced by a query to the client.
However, the RDSServer.DataFactory is limited to performing queries and updates. It cannot perform any validation or processing on the connect or command strings.
Starting with ADO 2.0, you can specify the DataFactory to work in conjunction with another type of server program called a Handler. The Handler can modify client connect and command strings before they are used to access the data source. In addition, the Handler can enforce access rights, which govern the ability of the client to read and write data to the data source.
The parameters the Handler uses to modify client parameters and access rights are specified in a customization file. The Handler parameters are specified in sections of the customization file.