XML and ADO.NET

XML and ADO.NET

ADO.NET can be used as a powerful XML middleware. Although coming from ADO, it has been entirely redesigned for a better support for Web applications. A main feature of ADO.NET is its disconnected recordsets, known as DataSet. It acts as a feature-rich in-memory database or data cache. In other words, it does not maintain any database server cursors. All recordset’s database characteristics are available in DataSet, such as sorting, paging, filtered views, relations, indexing, and primary/foreign keys.

Native support for XML is another principal feature for ADO.NET. In native mode, record tables are stored as XML documents where schema and data are treated as distinct and replaceable elements. It is quite different from ADO. The ADO native storage format for a recordset is the Advanced Data Table Gram (ADTG) file format, which is a proprietary, binary schema that represents a recordset’s in-memory image. The DataSet objects in ADO.NET can load its data from variant sources: a database server, a local or remote XML file and any accessible system resources. Once the data is loaded, they can be either treated as a record table or a virtual XML document. We principally discuss the latter. Now, I will give you several use cases. Each use case is a standalone unit test which can be run under NUnit. So you should install a latest version of NUnit. More information about its installation and usage can be found.

Before executing these examples, you should also setup an ODBC connection for the database with the following steps:

1.     Extract the download package. There is an access file ―NWIND_2002.MDB‖ in the folder ―UnitTest_ADO.NET_XML‖.

2.     Open Control Panel -> Administrative Tools -> Data Source.

3.     Choose the System Data Sources tab.

4.     Click ―Add‖ button and choose ―Microsoft Access Driver (*.mdb)‖ from the list. Then an

ODBC configuration dialog appears.

5.     Enter ―XmlDb_NorthWind‖ as the Data Source Name (DSN), and choose the Access file ―NWIND_2002.MDB‖ as the data source.