Essential ADO.NET

7.1. XML and Traditional Data Access

The preceding chapters have talked about the data access stack mostly as it relates to traditional data access and relational data. Each time, I've mentioned nonrelational data (homogeneous and heterogeneous hierarchies and semistructured data) almost as an afterthought, or to illustrate that it would be a stretch to support it by using the classes in System.Data. But a wide variety of data can be represented in a nonrelational way. Here are a few examples.

• LDAP readable directories, such as Active Directory, contain multivalued attributes. This violates relational theory's first normal form.

• Each item in the NT file system is either a directory or a file. This is an example of a heterogeneous hierarchy. A ...