ADO.NET in a Nutshell

Using the Data Objects to Edit XML

Editing relational tables through XML objects is rarely a good idea. You immediately introduce synchronization problems and lose the ability to enforce referential and identity integrity. There’s a more useful side of the ADO.NET and XML, however: using the ADO.NET data objects to work with an ordinary XML file.

For example, your program might need to store user-specific settings. One choice for a location to store these settings is the registry, but this isn’t always appropriate, particularly if users are regularly logging in to the program from different workstations. Another approach might be to use a central database server. However, you may not have the necessary database server in place, the program may need to support local (disconnected use), or you may not want to introduce additional network traffic. In these cases, you can adopt a different approach and assign a small XML configuration file to each user. To read and write the configuration file, use the DataSet.ReadXml( ) and DataSet.WriteXml( ) methods.

To evaluate this technique, here are a few considerations:

• This approach is best if you want to interact with the data using a table and row-based syntax. You don’t interact natively with the XML.

• This approach has the same limitations as any other file-based storage. If you need to write large amounts of data, it’s slow, and there is no way to manage concurrent updates. If you need these features, you need a full-fledged RDBMS.

• This approach ...