RFC 1777 (rfc1777) - Page 2 of 22

Lightweight Directory Access Protocol

RFC 1777                          LDAP                        March 1995


   implementations.

2.  Protocol Model

   The general model adopted by this protocol is one of clients
   performing protocol operations against servers. In this model, this
   is accomplished by a client transmitting a protocol request
   describing the operation to be performed to a server, which is then
   responsible for performing the necessary operations on the Directory.
   Upon completion of the necessary operations, the server returns a
   response containing any results or errors to the requesting client.
   In keeping with the goal of easing the costs associated with use of
   the Directory, it is an objective of this protocol to minimize the
   complexity of clients so as to facilitate widespread deployment of
   applications capable of utilizing the Directory.

   Note that, although servers are required to return responses whenever
   such responses are defined in the protocol, there is no requirement
   for synchronous behavior on the part of either client or server
   implementations: requests and responses for multiple operations may
   be exchanged by client and servers in any order, as long as clients
   eventually receive a response for every request that requires one.

   Consistent with the model of servers performing protocol operations
   on behalf of clients, it is also to be noted that protocol servers
   are expected to handle referrals without resorting to the return of
   such referrals to the client. This protocol makes no provisions for
   the return of referrals to clients, as the model is one of servers
   ensuring the performance of all necessary operations in the
   Directory, with only final results or errors being returned by
   servers to clients.

   Note that this protocol can be mapped to a strict subset of the
   directory abstract service, so it can be cleanly provided by the DAP.

3.  Mapping Onto Transport Services

   This protocol is designed to run over connection-oriented, reliable
   transports, with all 8 bits in an octet being significant in the data
   stream.  Specifications for two underlying services are defined here,
   though others are also possible.

3.1.  Transmission Control Protocol (TCP)

   The LDAPMessage PDUs are mapped directly onto the TCP bytestream.
   Server implementations running over the TCP should provide a protocol
   listener on port 389.




Yeong, Howes & Kille