Introduction
LDAP is the Lightweight Directory Access Protocol, and is a
protocol used to access "Directory Servers". The Directory is a
special kind of database that holds information in a tree
structure.
The concept is similar to your hard disk directory structure,
except that in this context, the root directory is "The world"
and the first level subdirectories are "countries". Lower levels
of the directory structure contain entries for companies,
organisations or places, while yet lower still we find directory
entries for people, and perhaps equipment or documents.
To refer to a file in a subdirectory on your hard disk, you might
use something like:
/usr/local/myapp/docs
The forwards slash marks each division in the reference, and the
sequence is read from left to right.
The equivalent to the fully qualified file reference in LDAP is
the "distinguished name", referred to simply as "dn". An example
dn might be:
cn=John Smith,ou=Accounts,o=My Company,c=US
The comma marks each division in the reference, and the sequence
is read from right to left. You would read this dn as:
country = US
organization = My Company
organizationalUnit = Accounts
commonName = John Smith
In the same way as there are no hard rules about how you organise
the directory structure of a hard disk, a directory server
manager can set up any structure that is meaningful for the
purpose. However, there are some conventions that are used. The
message is that you can not write code to access a directory
server unless you know something about its structure, any more
than you can use a database without some knowledge of what is
available.
Lots of information about LDAP can be found at
The Netscape SDK contains a helpful
» Programmer's Guide in
HTML format.
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