openldap/doc/guide/admin/backends.sdf
2007-08-02 21:54:20 +00:00

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# $OpenLDAP$
# Copyright 2007 The OpenLDAP Foundation, All Rights Reserved.
# COPYING RESTRICTIONS APPLY, see COPYRIGHT.
H1: Backends
H2: Berkley DB Backends
H3: Overview
The {{bdb}} backend to {{slapd}}(8) is the recommended primary backend for a
normal {{slapd}} database. It uses the Oracle Berkeley DB ({{TERM:BDB}})
package to store data. It makes extensive use of indexing and caching
(see the {{SECT:Tuning}} section) to speed data access.
{{hdb}} is a variant of the {{bdb}} backend that uses a hierarchical database
layout which supports subtree renames. It is otherwise identical to the {{bdb}}
behavior, and all the same configuration options apply.
Note: An {{hdb}} database needs a large {{idlcachesize}} for good search performance,
typically three times the {{cachesize}} (entry cache size) or larger.
H3: back-bdb/back-hdb Configuration
MORE LATER
H3: Further Information
{{slapd-bdb}}(5)
H2: LDAP
H3: Overview
The LDAP backend to {{slapd}}(8) is not an actual database; instead it acts
as a proxy to forward incoming requests to another LDAP server. While
processing requests it will also chase referrals, so that referrals are fully
processed instead of being returned to the {{slapd}} client.
Sessions that explicitly {{Bind}} to the {{back-ldap}} database always create
their own private connection to the remote LDAP server. Anonymous sessions
will share a single anonymous connection to the remote server. For sessions
bound through other mechanisms, all sessions with the same DN will share the
same connection. This connection pooling strategy can enhance the proxys
efficiency by reducing the overhead of repeatedly making/breaking multiple
connections.
The ldap database can also act as an information service, i.e. the identity
of locally authenticated clients is asserted to the remote server, possibly
in some modified form. For this purpose, the proxy binds to the remote server
with some administrative identity, and, if required, authorizes the asserted
identity.
H3: back-ldap Configuration
LATER
H3: Further Information
{{slapd-ldap}}(5)
H2: LDIF
H3: Overview
The LDIF backend to {{slapd}}(8) is a basic storage backend that stores
entries in text files in LDIF format, and exploits the filesystem to create
the tree structure of the database. It is intended as a cheap, low performance
easy to use backend, and it is exploited by higher-level internal structures
to provide a permanent storage.
When using Dynamic configuration over LDAP via {{cn=config}}, this is where all
configuration is stored if {{slapd}}(8) if started with {{-F}}. See {{slapd-config.5}}5)
for more information
H3: back-ldif Configuration
LATER
H3: Further Information
{{slapd-ldif}}(5)
H2: Metadirectory
H3: Overview
The meta backend to {{slapd}}(8) performs basic LDAP proxying with respect
to a set of remote LDAP servers, called "targets". The information contained
in these servers can be presented as belonging to a single Directory Information
Tree ({{TERM:DIT}}).
A basic knowledge of the functionality of the {{slapd-ldap}}(5) backend is
recommended. This backend has been designed as an enhancement of the ldap
backend. The two backends share many features (actually they also share portions
of code). While the ldap backend is intended to proxy operations directed
to a single server, the meta backend is mainly intended for proxying of
multiple servers and possibly naming context masquerading.
These features, although useful in many scenarios, may result in excessive
overhead for some applications, so its use should be carefully considered.
H3: back-meta Configuration
LATER
H3: Further Information
{{slapd-meta}}(5)
H2: Monitor
H3: Overview
The monitor backend to {{slapd}}(8) is not an actual database; if enabled,
it is automatically generated and dynamically maintained by slapd with
information about the running status of the daemon.
To inspect all monitor information, issue a subtree search with base {{cn=Monitor}},
requesting that attributes "+" and "*" are returned. The monitor backend produces
mostly operational attributes, and LDAP only returns operational attributes
that are explicitly requested. Requesting attribute "+" is an extension which
requests all operational attributes.
See the {{SECT:Monitoring}} section.
H3: back-monitor Configuration
LATER
H3: Further Information
{{slapd-monitor}}(5)
H2: Null
H3: Overview
The Null backend to {{slapd}}(8) is surely the most useful part of slapd:
- Searches return success but no entries.
- Compares return compareFalse.
- Updates return success (unless readonly is on) but do nothing.
- Binds other than as the rootdn fail unless the database option "bind on" is given.
- The slapadd(8) and slapcat(8) tools are equally exciting.
Inspired by the {{F:/dev/null}} device.
H3: back-null Configuration
LATER
H3: Further Information
{{slapd-null}}(5)
H2: Passwd
H3: Overview
The PASSWD backend to {{slapd}}(8) serves up the user account information
listed in the system {{passwd}}(5) file.
This backend is provided for demonstration purposes only. The DN of each entry
is "uid=<username>,<suffix>".
H3: back-passwd Configuration
LATER
H3: Further Information
{{slapd-passwd}}(5)
H2: Perl/Shell
H3: Overview
The Perl backend to {{slapd}}(8) works by embedding a {{perl}}(1) interpreter
into {{slapd}}(8). Any perl database section of the configuration file
{{slapd.conf}}(5) must then specify what Perl module to use. Slapd then creates
a new Perl object that handles all the requests for that particular instance of the backend.
The Shell backend to {{slapd}}(8) executes external programs to implement
operations, and is designed to make it easy to tie an existing database to the
slapd front-end. This backend is is primarily intended to be used in prototypes.
H3: back-perl/back-shell Configuration
LATER
H3: Further Information
{{slapd-shell}}(5) and {{slapd-perl}}(5)
H2: Relay
H3: Overview
The primary purpose of this {{slapd}}(8) backend is to map a naming context
defined in a database running in the same {{slapd}}(8) instance into a
virtual naming context, with attributeType and objectClass manipulation, if
required. It requires the rwm overlay.
This backend and the above mentioned overlay are experimental.
H3: back-relay Configuration
LATER
H3: Further Information
{{slapd-relay}}(5)
H2: SQL
H3: Overview
The primary purpose of this {{slapd}}(8) backend is to PRESENT information
stored in some RDBMS as an LDAP subtree without any programming (some SQL and
maybe stored procedures cant be considered programming, anyway ;).
That is, for example, when you (some ISP) have account information you use in
an RDBMS, and want to use modern solutions that expect such information in LDAP
(to authenticate users, make email lookups etc.). Or you want to synchronize or
distribute information between different sites/applications that use RDBMSes
and/or LDAP. Or whatever else...
It is NOT designed as a general-purpose backend that uses RDBMS instead of
BerkeleyDB (as the standard BDB backend does), though it can be used as such with
several limitations. You can take a look at {{URL:http://www.openldap.org/faq/index.cgi?file=378}}
(OpenLDAP FAQ-O-Matic/General LDAP FAQ/Directories vs. conventional databases)
to find out more on this point.
The idea is to use some meta-information to translate LDAP queries to SQL queries,
leaving relational schema untouched, so that old applications can continue using
it without any modifications. This allows SQL and LDAP applications to interoperate
without replication, and exchange data as needed.
The SQL backend is designed to be tunable to virtually any relational schema without
having to change source (through that meta-information mentioned). Also, it uses
ODBC to connect to RDBMSes, and is highly configurable for SQL dialects RDBMSes
may use, so it may be used for integration and distribution of data on different
RDBMSes, OSes, hosts etc., in other words, in highly heterogeneous environment.
This backend is experimental.
H3: back-sql Configuration
LATER
H3: Further Information
{{slapd-sql}}(5)