C# 4 and .NET 4

OC138 ❘ ChaPTer 52 directOry services
returns a DirectoryEntries collection that collects DirectoryEntry objects. You iterate through all
DirectoryEntry objects to display the name of the child objects:
using (var de = new DirectoryEntry())
{
de.Path = "LDAP://magellan/OU=thinktecture, DC=cninnovation, DC=local";
}
Console.WriteLine("Children of {0}", de.Name);
foreach (DirectoryEntry obj in de.Children)
{
Console.WriteLine(obj.Name);
}
code snippet DirectoryServicesSamples/Program.cs
When you run the program, the common names of the objects are displayed:
Children of OU=thinktecture
OU=Admin
CN=Buddhike de Silva
CN=Christian Nagel
CN=Christian Weyer
CN=Consultants
CN=demos
CN=Dominick Baier
CN=Ingo Rammer
CN=Neno Loye
In this example, you see all the objects in the organizational unit: users, contacts, printers, shares,
and others. If you want to display only some object types, you can use the SchemaFilter property of
the DirectoryEntries class. The SchemaFilter property returns a SchemaNameCollection. With this
SchemaNameCollection, you can use the Add() method to define the object types you want to see. Here,
you are just interested in seeing the user objects, so user is added to this collection:
using (var de = new DirectoryEntry())
{
de.Path = "LDAP://magellan/OU=thinktecture, DC=cninnovation, DC=local";
}
Console.WriteLine("Children of {0}", de.Name);
de.Children.SchemaFilter.Add("user");
foreach (DirectoryEntry obj in de.Children)
{
Console.WriteLine(obj.Name);
}
As a result, you see only the user objects in the organizational unit:
Cache
Children of OU=thinktecture
CN=Christian Nagel
CN=Christian Weyer
CN=Dominick Baier
CN=Ingo Rammer
CN=Jörg Neumann
CN=Richard Blewett
To reduce the network transfers, ADSI uses a cache for the object properties. As mentioned earlier, the
server isn’t accessed when a DirectoryEntry object is created; instead, with the first reading of a value
from the directory store, all the properties are written into the cache so that a round trip to the server isn’t
necessary when the next property is accessed.
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