.TH SLAPD-RELAY 5 "RELEASEDATE" "OpenLDAP LDVERSION"
.SH NAME
slapd-relay \- relay backend to slapd
.SH SYNOPSIS
ETCDIR/slapd.conf
.SH DESCRIPTION
The primary purpose of this
.BR slapd (8)
backend is to map a naming context defined in a database 
running in the same 
.BR slapd (8)
instance into a virtual naming context, with attributeType
and objectClass manipulation, if required.
It requires the
.B rwm
.BR overlay .
.LP
This backend and the above mentioned overlay are experimental.
.SH CONFIGURATION
These
.B slapd.conf
options apply to the relay backend database.
That is, they must follow a "database relay" line and come before any
subsequent "backend" or "database" lines.
Other database options are described in the
.BR slapd.conf (5)
manual page.
.TP
.B relay <real naming context> [massage]
The naming context of the database that is presented 
under a virtual naming context.
The presence of the directive implies that one single database
will be presented under a virtual naming context.
This directive automatically instantiates the 
.B rwm
.BR overlay .
If the optional
.B massage
keyword is present, the suffix massaging is automatically
configured as well.

.SH SCENARIOS
.LP
If no
.B relay
directive is given, the 
.B relay
database does not refer to any specific database, but the most
appropriate one is looked-up after rewriting the request DN
for the operation that is being handled.
.LP
This allows to write carefully crafted rewrite rules that
cause some of the requests to be directed to one database, and
some to another; e.g., authentication can be mapped to one 
database, and searches to another and so.
.LP
Another possibility is to map the same operation to different 
databases based on details of the virtual naming context,
e.g. groups on one database and persons on another.
.LP
.SH Caveats
The
.B rwm overlay
is far from complete.
.LP
.SH EXAMPLES
To implement a plain virtual naming context mapping
that refers to a single database, use
.LP
.nf
  database        relay
  suffix          "dc=virtual,dc=naming,dc=context"
  relay           "dc=real,dc=naming,dc=context" massage
.fi
.LP
To implement a plain virtual naming context mapping
that looks up the real naming context for each operation, use
.LP
.nf
  database        relay
  suffix          "dc=virtual,dc=naming,dc=context"
  overlay         rwm
  suffixmassage   "dc=virtual,dc=naming,dc=context"
          "dc=real,dc=naming,dc=context"
.fi
.LP
To implement the old-fashioned suffixalias, e.g. mapping
the virtual to the real naming context, but not the results
back from the real to the virtual naming context, use
.LP
.nf
  database        relay
  suffix          "dc=virtual,dc=naming,dc=context"
  relay           "dc=real,dc=naming,dc=context"
  rewriteEngine   on
  rewriteContext  default
  rewriteRule     "dc=virtual,dc=naming,dc=context"
          "dc=real,dc=naming,dc=context" ":"
  rewriteRule     searchFilter
  rewriteRule     searchResult
  rewriteRule     searchResultAttrDN
  rewriteRule     matchedDN
.fi
.LP
Note that the virtual database is bound to a single real database,
so the 
.B rwm overlay
is automatically instantiated, but the rewrite rules 
are written explicitly to map all the virtual to real 
naming context data flow, but none of the real to virtual.
.SH FILES
.TP
ETCDIR/slapd.conf
default slapd configuration file
.SH SEE ALSO
.BR slapd.conf (5),
.BR slapd (8).