Everything you have read in the preceding chapters on coding in Visual Studio .NET applies to creating Web services. In addition to the commands covered already, .NET provides classes to help you work with data. In comes ADO.NET.
In Chapter 13, you were introduced to the concept of assemblies, namespaces, and classes. One of the namespaces that can be found in .NET is the System.Data namespace. This namespace makes up ADO.NET, which is a set of classes created to assist developers who work with data using the .NET Framework.
If you have done any development for the desktop using Visual Basic or VBA in the last couple of years, especially when dealing with data, then you have probably used ActiveX Data Objects ( ADO). ADO has an object model created for the purpose of manipulating data using code. On the .NET platform ADO.NET is used.
The main difference between ADO and ADO.NET, besides specific objects, is the concept of connected data (ADO) versus disconnected data (ADO.NET). In both versions of ADO, you will use a Connection object, but in .NET the data is loaded either on the local computer or on the server using XML. The connection is then broken until the data is resubmitted to the source data. The ADO.NET objects, using properties, handle synchronization of data.
In ADO the main object was the Recordset, whereas in ADO.NET it is the DataSet. ...