This chapter describes how to manage computed attributes. It contains the following topics:
Oracle Internet Directory server provides the OrclComputedAttribute attribute as a mechanism to dynamically compute a configurable attribute and its value based on one or more rules. Thus, an attribute can be computed when it is actually needed, without requiring that the attribute persist in the directory store. Computed attributes can be useful in the transition from a test to a production deployment.
The OrclComputedAttribute attribute is a configuration attribute in the DSA Configuration entry:
cn=dsaconfig,cn=configsets,cn=oracle internet directory.
OrclComputedAttribute is a multivalued attribute, so multiple attributes and their values can be computed dynamically.
An OrclComputedAttribute value can be derived from the following items, or a combination of these items, which are defined in the rules:
A standard LDAP URI, as defined in RFC 4516
A predetermined string
An attribute value
A function of an attribute value
Considerations for using OrclComputedAttribute include:
The computed attribute name must be defined in the schema.
The computed attribute might have access control policies that prevent the return of its value.
Computed attributes are derived only for lookup and search operations. If the result entry has a configured computed attribute, then Oracle Internet Directory server skips computation of the attribute.
Update operations are allowed for removing or replacing an existing value in the entry.
You can configure OrclComputedAttribute using LDAP tools such as ldapmodify, Oracle Directory Services Manager, or third-party LDAP browsers.
This section describes these topics:
This section describes the syntax used for the rules used to compute the attribute values.
If you can use a combination of these rules to compute a value, see the Special Characters entry in Table 17-1.
The rules use the following syntax:
OrclComputedAttribute;ComputedAttrName;dn;Filter: ldapURI OrclComputedAttribute;ComputedAttrName;dn;Filter: "anyString" OrclComputedAttribute;ComputedAttrName;dn;Filter: AttributeName OrclComputedAttribute;ComputedAttrName;dn;Filter: Func(attrName)
Table 17-1 describes the elements used in these rules.
Table 17-1 Syntax Elements Used in Rules for Computed Attributes
| Element | Description |
|---|---|
|
ComputedAttrName |
Name of the attribute that should be returned with the entry. The computed attribute name must be defined in the schema. The attribute is also subject to ACL evaluation after the value is computed. |
|
dn |
Distinguished name. The attribute is computed for child entries under this DN. |
|
Filter |
Filter value. The attribute is computed for entries that belong to this filter value. |
|
ldapURI |
URI that conforms to the syntax described in RFC 4516, as follows: ldap:///baseDN?ReqdAttribute??scope?filter ReqdAttribute is a single attribute name for a required attribute. If there is a space character in the ldapURI configuration, the space must be encoded as |
|
"anyString" |
String to be included. It must be enclosed by double quote characters. |
|
AttributeName |
Attribute name that indicates the value of that attribute should be used. |
|
|
Name of a function to perform on the value. In Release 11g (11.1.1.7.0), the following functions are available: lower(attrName) upper(attrName) substr(attrName,pos,len) replace(attrName,"str") trunc(attrName, "c") |
|
Special Characters |
Special characters that can be used with the rules are:
|
This section provides the following examples for using computed attributes:
Section 17.2.2.1, "Returning an Attribute Value as Uppercase"
Section 17.2.2.2, "Returning the Substring of an Attribute Value"
This example computes the cn attribute as uppercase and returns the attribute as upperattr:
dn: cn=dsaconfig,cn=configsets,cn=oracle internet directory changetype: modify add: orclcomputedattribute;upperattr;dc=acme,dc=com;objectclass=person orclcomputedattribute;upperattr;ou=EuroSInet Suite,o=IMC,c=US;objectclass=person: upper(cn)
The schema definition for upperattr must be defined.
This example computes the substring of the attribute value and returns the attribute substrattr with the value as description value from position 1 for the next 3 characters:
dn: cn=dsaconfig,cn=configsets,cn=oracle internet directory changetype: modify add: orclcomputedattribute;substrattr;dc=acme,dc=com;objectclass=person orclcomputedattribute;substrattr;dc=acme,dc=com;objectclass=person: substr(description, 1,3)
This example computes and replaces the attribute value for newTitle:
dn: cn=dsaconfig,cn=configsets,cn=oracle internet directory changetype: modify add: orclcomputedattribute;newTitle;cn=john doe,dc=acme,dc=com;objectclass=person orclcomputedattribute;newTitle;ou=EuroSInet Suite,o=IMC,c=US;objectclass=person: replace(title, "Clerk", "Manager")
This example adds commonTelephoneNumber to every entry under dc=acme,dc=com:
dn: cn=dsaconfig,cn=configsets,cn=oracle internet directory changetype: modify add: orclcomputedattribute;commonTelephoneNumber;dc=acme,dc=com;objectclass=person orclcomputedattribute;commonTelephoneNumber;dc=acme,dc=com,c=US;objectclass=person: "Common PhoneNumber is " + ldap:///cn=common%20attributes,dc=com?telephonenumber??base?objectclass=*
Concatenate different rules using a + (plus sign) with the rules separated by a space character:
dn: cn=dsaconfig,cn=configsets,cn=oracle internet directory changetype: modify add: orclcomputedattribute;combinationAttribute;ou=EuroSInet Suite,o=IMC,c=US;objectclass=person orclcomputedattribute;combinationAttribute;dc=acme,dc=com;objectclass=person: "telephone number from common entry:" + ldap:///cn=common Entry,?telephonenumber??base?objectclass=* + " appending replace of title attr with clerk/manager " + replace(title, "Clerk", "Manager")
dn: cn=dsaconfig,cn=configsets,cn=oracle internet directory changetype: modify add: orclcomputedattribute;combinationAttr2;dc=acme,dc=com;objectclass=person orclcomputedattribute;combinationAttr2;dc=acme,dc=com;objectclass=person: "Telephone number from common entry " + ldap:///cn=commonEntry,dc=acme,dc=com?telephonenumber??base?objectclass=* + " appending truncate of description for space char " + trunc(description, " ")
Add the contactNumber attribute as telephoneNumber if the entry has the telephoneNumber attribute; otherwise, copy the value 6505067000:
dn: cn=dsaconfig,cn=configsets,cn=oracle internet directory changetype: modify add: orclcomputedattribute;contactNumber;cn=employees,dc=acme,dc=com; (objectclass=person) orclcomputedattribute;contactNumber;cn=employees,dc=acme,dc=com; (objectclass=person): telephonenumber | 6505067000
Note:
For the OR operator (|), the computed attribute definition supports the following syntax:
definition-1 | definition-2 | ... definition-n
where:
definition-1 can be a complex rule.
definition-2 through definition-n must be a simple rule only, such as a hard-coded string or an attribute value. These definitions cannot be function expressions or a combination of expression rules.
For example, for the following rule, if the uid is not present for an entry, the result will be a computed value "cn=", regardless of the number of occurences of the attribute cn in the entry:
orclcomputedattr;myattr;cn=employees;(objectclass=inetorgperson): "uid=" + uid | "cn=" + cn