28.3 Overview of System.DirectoryServices

The System.DirectoryServices namespace contains several classes, many of which were built on top of ADSI. If you are already familiar with ADSI, the learning curve for the System.DirectoryServices classes should be pretty minimal. Table 28-1 contains the base classes contained within the System.DirectoryServices namespace.

Table 28-1. System.DirectoryServices classes

Class name	Description
DirectoryEntries	Contains the children (child entries) of an entry in Active Directory.
DirectoryEntry	Encapsulates a node or object in the Active Directory hierarchy.
DirectorySearcher	Performs queries against Active Directory.
DirectoryServicesPermission	Allows control of code access security permissions for System.DirectoryServices.
DirectoryServicesPermissionAttribute	Allows declarative System.DirectoryServices permission checks.
DirectoryServicesPermissionEntry	Defines the smallest unit of a code access security permission set for System.DirectoryServices.
DirectoryServicesPermissionEntryCollection	Contains a strongly typed collection of DirectoryServicesPermissionEntry objects.
PropertyCollection	Contains the properties of a DirectoryEntry.
PropertyValueCollection	Contains the values of a DirectoryEntry property.
ResultPropertyCollection	Contains the properties of a SearchResult instance.
ResultPropertyValueCollection	Contains the values of a SearchResult property.
SchemaNameCollection	Contains a list of the schema names that the SchemaFilter property of a DirectoryEntries object can use.
SearchResult	Encapsulates a node in the Active Directory hierarchy that is returned during a search through DirectorySearcher.
SearchResultCollection	Contains the SearchResult instances that the Active Directory hierarchy returned during a DirectorySearcher query.
SortOption	Specifies how to sort the results of a search.

The list of classes in Table 28-1 was taken from the Microsoft Developer Network (http://msdn.microsoft.com). For more information on System.DirectoryServices and the .NET Framework, check out the .NET web site: http://msdn.microsoft.com/netframework/.

The two main classes within System.DirectoryServices are DirectoryEntry and DirectorySearcher. The DirectoryEntry class represents an object in Active Directory. You can create new objects and manage existing ones with DirectoryEntry. The DirectorySearcher class is the primary interface for searching Active Directory. It is an easy-to-use interface that contains properties for all the typical options you need to set when performing LDAP-based queries. We will be touching on some of the other classes as we go along, but these two are the main ones to become familiar with.