LDAP Primer for Developers
What is LDAP? The P in LDAP stands for Protocol, the same as the P in HTTP and FTP. So right off the bat you see that LDAP is a protocol that is at the application level (same as FTP and HTTP) that rides on top of TCP/IP (a transport level protocol). Like HTTP and FTP, LDAP is based on a client sever model. You have an LDAP client that connects to an LDAP server and sends LDAP requests and receives LDAP responses. LDAP services typicallly run on port 389. Unlike HTTP which is a stateless protocol (no connection is kept alive between requests by a client), LDAP is more like FTP in that you have to connect with credentials (called binding), perform operations (typically to lookup data in the directory) and then disconnect (aka unbinding). An interesting thing is that LDAP is supported by browsers (just like FTP is also supported by browsers) and you can enter an address like ldap://UrlAddress/ and the browser will switch to the LDAP protocol and pop up a small window to let you do dire