# $OpenLDAP$
-# Copyright 1999-2000, The OpenLDAP Foundation, All Rights Reserved.
+# Copyright 1999-2005, The OpenLDAP Foundation, All Rights Reserved.
# COPYING RESTRICTIONS APPLY, see COPYRIGHT.
H1: Schema Specification
-This chapter describes how to extend the schema used by {{slapd}}(8).
+This chapter describes how to extend the user schema used by
+{{slapd}}(8). The chapter assumes the reader is familar with the
+{{TERM:LDAP}}/{{TERM:X.500}} information model.
+
The first section, {{SECT:Distributed Schema Files}} details optional
schema definitions provided in the distribution and where to obtain
other definitions.
to {{slapd.conf}}(5) format.
!endif
+This chapter does not discuss how to extend system schema used by
+{{slapd}}(8) as this requires source code modification. System
+schema includes all operational attribute types or any object class
+which allows or requires an operational attribute (directly or
+indirectly).
+
+
H2: Distributed Schema Files
OpenLDAP is distributed with a set of schema specifications for
{{F:/usr/local/etc/openldap/schema}} directory.
!block table; colaligns="LR"; coltags="F,N"; align=Center; \
- title="Table 6.1: Provided Schema Specifications"
+ title="Table 8.1: Provided Schema Specifications"
File Description
core.schema OpenLDAP {{core}} (required)
cosine.schema Cosine and Internet X.500 (useful)
inetorgperson.schema InetOrgPerson (useful)
misc.schema Assorted (experimental)
-nadf.schema North American Directory Forum (FYI)
nis.schema Network Information Services (FYI)
openldap.schema OpenLDAP Project (experimental)
!endblock
To use any of these schema files, you only need to include the
-the desired file in the global definitions portion of your
+desired file in the global definitions portion of your
{{slapd.conf}}(5) file. For example:
> # include schema
Note: You should not modify any of the schema items defined
in provided files.
+
H2: Extending Schema
Schema used by {{slapd}}(8) may be extended to support additional
-syntaxes, matching rules, attribute types, and object classes.
-This chapter details how to add attribute types and object classes
-using the syntaxes and matching rules already supported by slapd.
-slapd can also be extended to support additional syntaxes
-and matching rules, but this requires some programming and hence
-is not discussed here.
+syntaxes, matching rules, attribute types, and object classes. This
+chapter details how to add user application attribute types and
+object classes using the syntaxes and matching rules already supported
+by slapd. slapd can also be extended to support additional syntaxes,
+matching rules and system schema, but this requires some programming
+and hence is not discussed here.
There are five steps to defining new schema:
^ obtain Object Identifer
+ define custom attribute types (if necessary)
+ define custom object classes
+
H3: Object Identifiers
-Each schema element is identified by a globally unique
-{{TERM[expand]OID}} (OID). OIDs are also used to identify
-other objects.
-They are commonly found in protocols described by {{TERM:ASN.1}}. In
+Each schema element is identified by a globally unique {{TERM[expand]OID}}
+(OID). OIDs are also used to identify other objects. They are
+commonly found in protocols described by {{TERM:ASN.1}}. In
particular, they are heavily used by the {{TERM[expand]SNMP}} (SNMP).
-As OIDs are hierarchical, your organization
-can obtain one OID and branch it as needed. For example,
-if your organization were assigned OID {{EX:1.1}}, you could branch
-the tree as follows:
+As OIDs are hierarchical, your organization can obtain one OID and
+branch it as needed. For example, if your organization were assigned
+OID {{EX:1.1}}, you could branch the tree as follows:
!block table; colaligns="LR"; coltags="EX,N"; align=Center; \
- title="Table 6.2: Example OID hierarchy"
+ title="Table 8.2: Example OID hierarchy"
OID Assignment
1.1 Organization's OID
1.1.1 SNMP Elements
!endblock
You are, of course, free to design a hierarchy suitable to your
-organizational needs under your organization's OID. No matter
-what hierarchy you choose, you should maintain a registry of
-assignments you make. This can be a simple flat file or a
-something more sophisticated such as the {{OpenLDAP OID Registry}}
+organizational needs under your organization's OID. No matter what
+hierarchy you choose, you should maintain a registry of assignments
+you make. This can be a simple flat file or something more
+sophisticated such as the {{OpenLDAP OID Registry}}
({{URL:http://www.openldap.org/faq/index.cgi?file=197}}).
-For more information about Object Identifers (and a listing
-service) see {{URL:http://www.alvestrand.no/harald/objectid/}}.
+For more information about Object Identifers (and a listing service)
+see {{URL:http://www.alvestrand.no/harald/objectid/}}.
-.{{Under no circumstances should you use a fictious OID!}}
+.{{Under no circumstances should you hijack OID namespace!}}
-To obtain a fully registered OID at {{no cost}}, apply for
-an OID under {{ORG[expand]IANA}} (IANA) maintained
-{{Private Enterprise}} arch. Any private enterprise (organization)
-may request an OID to be assigned under this arch. Just fill
-out the {{ORG:IANA}} form at {{URL: http://www.iana.org/cgi-bin/enterprise.pl}}
-and your official OID will be sent to you usually within a few days.
-Your base OID will be something like {{EX:1.3.6.1.4.1.X}} were {{EX:X}}
+To obtain a registered OID at {{no cost}}, apply for an OID under
+the {{ORG[expand]IANA}} (IANA) maintained {{Private Enterprise}}
+arc. Any private enterprise (organization) may request an OID to
+be assigned under this arc. Just fill out the {{ORG:IANA}} form
+at {{URL: http://www.iana.org/cgi-bin/enterprise.pl}} and your
+official OID will be sent to you usually within a few days. Your
+base OID will be something like {{EX:1.3.6.1.4.1.X}} where {{EX:X}}
is an integer.
-Note: Don't let the "MIB/SNMP" statement on the IANA page confuse you.
-OIDs obtained using this form may be used for any purpose including
-identifying LDAP schema elements.
+Note: Don't let the "MIB/SNMP" statement on the IANA page confuse
+you. OIDs obtained using this form may be used for any purpose
+including identifying LDAP schema elements.
+
+Alternatively, OID name space may be available from a national
+authority (e.g., {{ORG:ANSI}}, {{ORG:BSI}}).
H3: Name Prefix
In addition to assigning a unique object identifier to each schema
element, you should provide a least one textual name for each
-element. The name should be both descriptive and not likely
-to clash with names of other schema elements. In particular,
-any name you choose should not clash with present or future
-Standard Track names.
+element. The name should be both descriptive and not likely to
+clash with names of other schema elements. In particular, any name
+you choose should not clash with present or future Standard Track
+names.
-To reduce (but not eliminate) the potential for name clashes,
-the convention is to prefix names of non-Standard Track with
-a few letters to localize the changes to your organization.
-The smaller the organization, the longer your prefix should
-be.
+To reduce (but not eliminate) the potential for name clashes, the
+convention is to prefix names of non-Standard Track with a few
+letters to localize the changes to your organization. The smaller
+the organization, the longer your prefix should be.
-In the examples below, we have choosen a short prefix '{{EX:my}}'
-(to save space). Such a short prefix would only be suitable for
-a very large, global organization. For a small, local organization,
-we recommend something like '{{EX:deFirm}}' (German company) or
-'{{EX:comExample}}' (elements associated with organization associated
-with {{EX:example.com}}).
+In the examples below, we have chosen a short prefix '{{EX:my}}'
+(to save space). Such a short prefix would only be suitable for a
+very large, global organization. In general, we recommend something
+like '{{EX:deFirm}}' (German company) or '{{EX:comExample}}' (elements
+associated with organization associated with {{EX:example.com}}).
H3: Local schema file
> [ "EQUALITY" woid ; Matching Rule name
> [ "ORDERING" woid ; Matching Rule name
> [ "SUBSTR" woid ] ; Matching Rule name
-> [ "SYNTAX" whsp noidlen whsp ] ; see section 4.3
+> [ "SYNTAX" whsp noidlen whsp ] ; Syntax OID
> [ "SINGLE-VALUE" whsp ] ; default multi-valued
> [ "COLLECTIVE" whsp ] ; default not collective
> [ "NO-USER-MODIFICATION" whsp ]; default user modifiable
>
where whsp is a space ('{{EX: }}'), numericoid is a globally unique
-OID in dotted-decimal form (e.g. {{EX:1.2.3}}), qdescrs is one or more
-names, woid is either the name or OID, and noidlen is an optional length
-specifier (e.g {{EX:{10}}}).
+OID in dotted-decimal form (e.g. {{EX:1.1.0}}), qdescrs is one or
+more names, woid is either the name or OID optionally followed
+by a length specifier (e.g {{EX:{10}}}).
For example, the attribute types {{EX:name}} and {{EX:cn}} are defined
in {{F:core.schema}} as:
> attributeType ( 2.5.4.41 NAME 'name'
+> DESC 'name(s) associated with the object'
> EQUALITY caseIgnoreMatch
> SUBSTR caseIgnoreSubstringsMatch
> SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768} )
-> attributeType ( 2.5.4.3 NAME
-> ( 'cn' $ 'commonName' ) SUP name )
-
-Notice that each defines the attribute's OID and descriptive
-names. Each name is an alias for the OID. {{slapd}}(8) returns
-the first listed name when returning results.
+> attributeType ( 2.5.4.3 NAME ( 'cn' 'commonName' )
+> DESC 'common name(s) assciated with the object'
+> SUP name )
-The first attribute, {{EX:name}}, has a syntax of {{EX:directoryString}}
-(a UTF-8 encoded Unicode string) with a recommend maximun length.
-Note that syntaxes are specified by OID. In addition, the equality
-and substring matching uses case ignore rules. Below are tables
-listing commonly used supported syntax and matching rules.
+Notice that each defines the attribute's OID, provides a short name,
+and a brief description. Each name is an alias for the OID.
+{{slapd}}(8) returns the first listed name when returning results.
+
+The first attribute, {{EX:name}}, holds values of {{EX:directoryString}}
+(UTF-8 encoded Unicode) syntax. The syntax is specified by OID
+(1.3.6.1.4.1.1466.115.121.1.15 identifies the directoryString
+syntax). A length recommendation of 32768 is specified. Servers
+should support values of this length, but may support longer values
+The field does NOT specify a size constraint, so is ignored on
+servers (such as slapd) which don't impose such size limits. In
+addition, the equality and substring matching uses case ignore
+rules. Below are tables listing commonly used syntax and
+matching rules (OpenLDAP supports these and many more).
!block table; align=Center; coltags="EX,EX,N"; \
- title="Table 6.3: Supported Syntaxes"
+ title="Table 8.3: Commonly Used Syntaxes"
Name OID Description
-binary 1.3.6.1.4.1.1466.115.121.1.5 BER/DER data
boolean 1.3.6.1.4.1.1466.115.121.1.7 boolean value
-distinguishedName 1.3.6.1.4.1.1466.115.121.1.12 DN
-directoryString 1.3.6.1.4.1.1466.115.121.1.15 UTF-8 string
-IA5String 1.3.6.1.4.1.1466.115.121.1.26 ASCII string
-Integer 1.3.6.1.4.1.1466.115.121.1.27 integer
-Name and Optional UID 1.3.6.1.4.1.1466.115.121.1.34 DN plus UID
-Numeric String 1.3.6.1.4.1.1466.115.121.1.36 numeric string
+directoryString 1.3.6.1.4.1.1466.115.121.1.15 Unicode (UTF-8) string
+distinguishedName 1.3.6.1.4.1.1466.115.121.1.12 LDAP DN
+integer 1.3.6.1.4.1.1466.115.121.1.27 integer
+numericString 1.3.6.1.4.1.1466.115.121.1.36 numeric string
OID 1.3.6.1.4.1.1466.115.121.1.38 object identifier
-Octet String 1.3.6.1.4.1.1466.115.121.1.40 arbitary octets
-Printable String 1.3.6.1.4.1.1466.115.121.1.44 printable string
+octetString 1.3.6.1.4.1.1466.115.121.1.40 arbitary octets
!endblock
>
!block table; align=Center; coltags="EX,N"; \
- title="Table 6.4: Supported Matching Rules"
-Name Type Description
-booleanMatch equality boolean
-objectIdentiferMatch equality OID
-distinguishedNameMatch equality DN
-uniqueMemberMatch equality DN with optional UID
-numericStringMatch equality numerical
-numericStringOrderingMatch ordering numerical
-numericStringSubstringsMatch substrings numerical
-caseIgnoreMatch equality case insensitive, space insensitive
-caseIgnoreOrderingMatch ordering case insensitive, space insensitive
-caseIgnoreSubstringsMatch substrings case insensitive, space insensitive
-caseExactMatch equality case sensitive, space insensitive
-caseExactOrderingMatch ordering case sensitive, space insensitive
-caseExactSubstringsMatch substrings case sensitive, space insensitive
-caseIgnoreIA5Match equality case insensitive, space insensitive
-caseIgnoreIA5OrderingMatch ordering case insensitive, space insensitive
-caseIgnoreIA5SubstringsMatch substrings case insensitive, space insensitive
-caseExactIA5Match equality case sensitive, space insensitive
-caseExactIA5OrderingMatch ordering case sensitive, space insensitive
-caseExactIA5SubstringsMatch substrings case sensitive, space insensitive
+ title="Table 8.4: Commonly Used Matching Rules"
+Name Type Description
+booleanMatch equality boolean
+caseIgnoreMatch equality case insensitive, space insensitive
+caseIgnoreOrderingMatch ordering case insensitive, space insensitive
+caseIgnoreSubstringsMatch substrings case insensitive, space insensitive
+caseExactMatch equality case sensitive, space insensitive
+caseExactOrderingMatch ordering case sensitive, space insensitive
+caseExactSubstringsMatch substrings case sensitive, space insensitive
+distinguishedNameMatch equality distinguished name
+integerMatch equality integer
+integerOrderingMatch ordering integer
+numericStringMatch equality numerical
+numericStringOrderingMatch ordering numerical
+numericStringSubstringsMatch substrings numerical
+octetStringMatch equality octet string
+octetStringOrderingStringMatch ordering octet string
+octetStringSubstringsStringMatch ordering octet string
+objectIdentiferMatch equality object identifier
!endblock
The second attribute, {{EX:cn}}, is a subtype of {{EX:name}} hence
it inherits the syntax, matching rules, and usage of {{EX:name}}.
{{EX:commonName}} is an alternative name.
-Neither attribute is restricted to a single value and both are
-meant for usage by user applications. You likely won't need to
-specify other parameters such as {{EX:OBSOLETE}}.
+Neither attribute is restricted to a single value. Both are meant
+for usage by user applications. Neither is obsolete nor collective.
The following subsections provide a couple of examples.
> SYNTAX 1.3.6.1.4.1.1466.115.121.1.40
> SINGLE-VALUE )
-As noted in the description, LDAP has no knowledge of the
-format of the photo. It's assumed that all applications
-accessing this attribute agree on the handling of values.
+In this case, the syntax doesn't specify the format of the photo.
+It's assumed (maybe incorrectly) that all applications accessing
+this attribute agree on the handling of values.
If you wanted to support multiple photo formats, you could define
a separate attribute type for each format, prefix the photo
Another alternative is for the attribute to hold a {{TERM:URI}}
pointing to the photo. You can model such an attribute after
-{{EX:labeledURI}} ({{REF:RFC2079}}).
+{{EX:labeledURI}} ({{REF:RFC2079}}) or simply create a subtype,
+e.g.:
+
+> attributetype ( 1.1.2.1.3 NAME 'myPhotoURI'
+> DESC 'URI and optional label referring to a photo'
+> SUP labeledURI )
H3: Object Class Specification
> whsp ")"
where whsp is a space ('{{EX: }}'), numericoid is a globally unique
-OID in numeric form (e.g. {{EX:1.2.3}}), qdescrs is one or more
+OID in numeric form (e.g. {{EX:1.1.0}}), qdescrs is one or more
names, and oids is one or more names and/or OIDs.
> objectclass ( 1.1.2.2.2 NAME 'myPerson'
> DESC 'my person'
> SUP inetOrgPerson
-> MUST ( 'myUniqueName' $ 'givenName' )
-> MAY 'myPhoto' )
+> MUST ( myUniqueName $ givenName )
+> MAY myPhoto )
The object class inherits the required/allowed attribute
types of {{EX:inetOrgPerson}} but requires {{EX:myUniqueName}}
{{slapd}}(8).
LDAPv3 servers publish schema elements in special {{subschema}}
-entries (or subentries). {{slapd}}(8) publishes a single subschema
-entry normally named {{EX:cn=Subschema}}. If a server which
-supports a single subschema subentry, the DN of the subschema
-subenty can usually be found by examining the value of the
-{{EX:subschemaSubentry}} attribute type in the {{root DSE}}
-Other servers may publish multiple subschema entries. These
-can be located by examining the {{EX:subschemaSubentry}} attribute
-contained in the entry at the root of each administrative context.
+entries (or subentries). While {{slapd}}(8) publishes a single
+subschema subentry normally named {{EX:cn=Subschema}}, this behavior
+cannot be expected from other servers. The subschema subentry
+controlling a particular entry can be obtained by examining the
+{{EX:subschemaSubentry}} attribute contained in the entry at the
+root of each administrative context. For example,
+
+> ldapsearch -LLL -x -b "dc=example,dc=com" -s base "(objectclass=*)" subschemaSubentry
To obtain the schema from a subschema subentry, you can use
ldapsearch(1) as follows (replace the search base as needed):
> ldapsearch -LLL -x -b "cn=Subschema" -s base "(objectclass=subschema)" attributeTypes objectClasses
+where "cn=Subschema" is the value of subschemaSubentry returned in
+the prior search.
+
This will return {{TERM:LDIF}} output containing many type/value
pairs. The following is an abbreviated example:
> dn: cn=Subschema
+> objectClasses: ( 1.1.2.2.2 NAME 'myPerson' DESC 'my person' SUP inet
+> OrgPerson MUST ( myUniqueName $ givenName ) MAY myPhoto )
> attributeTypes: ( 1.1.2.1.1 NAME 'myUniqueName' DESC 'unique name wi
> th my organization' EQUALITY caseIgnoreMatch SUBSTR caseIgnoreSubst
> ringsMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 SINGLE-VALUE )
> attributeTypes: ( 1.1.2.1.2 NAME 'myPhoto' DESC 'a photo (applicatio
> n defined format)' SYNTAX 1.3.6.1.4.1.1466.115.121.1.40
-> objectClasses: ( 1.1.2.2.2 NAME 'myPerson' DESC 'my person' SUP inet
-> OrgPerson MUST ( 'myUniqueName' $ 'givenName' ) MAY 'myPhoto' )
Capture the output of the search in a file and then edit the file:
+ to contain only desired type/value pairs
^ join LDIF continuation lines
^ replace attribute type with directive name
-(e.g. {{EX:s/attributeTypes:/attributeType/}} and
-{{EX:s/objectClasses:/objectClass/}}).
+(e.g. {{EX:s/attributeTypes:/attributeType /}} and
+{{EX:s/objectClasses:/objectClass /}}).
+^ reorder lines so each element is defined before first use
^ continue long directives over multiple lines
For the three type/value pairs in our example, the edit should
> objectClass ( 1.1.2.2.2 NAME 'myPerson'
> DESC 'my person'
> SUP inetOrgPerson
-> MUST ( 'myUniqueName' $ 'givenName' )
-> MAY 'myPhoto' )
+> MUST ( myUniqueName $ givenName )
+> MAY myPhoto )
-Save in an appropriately named file (e.g. {{F:my.schema}}).
-You may now include this file in your {{slapd.conf}}(8) file.
+Save in an appropriately named file (e.g. {{F:local.schema}}).
+You may now include this file in your {{slapd.conf}}(5) file.
!endif
+
+
+H3: OID Macros
+
+To ease the management and use of OIDs, {{slapd}}(8) supports
+{{Object Identifier}} macros. The {{EX:objectIdentifier}} directive
+is used to equate a macro (name) with a OID. The OID may possibly
+be derived from a previously defined OID macro. The {{slapd.conf}}(5)
+syntax is:
+
+E: objectIdentifier <name> { <oid> | <name>[:<suffix>] }
+
+The following demonstrates definition of a set of OID macros
+and their use in defining schema elements:
+
+> objectIdentifier myOID 1.1
+> objectIdentifier mySNMP myOID:1
+> objectIdentifier myLDAP myOID:2
+> objectIdentifier myAttributeType myLDAP:1
+> objectIdentifier myObjectClass myLDAP:2
+> attributetype ( myAttributeType:3 NAME 'myPhotoURI'
+> DESC 'URI and optional label referring to a photo'
+> SUP labeledURI )
+> objectclass ( myObjectClass:1 NAME 'myPhotoObject'
+> DESC 'mixin myPhoto'
+> AUXILIARY
+> MAY myPhoto )
+