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name-like attributes such as surname. We didn’t need to define the syntax for
“sn” because it inherits this from “name”.
Note in the third example, “mail”, it also has an alias of “rfc822mailbox”. As you
may have guessed, the “EQUALITY” and “SYNTAX” are yet more ASN.1
definitions.
It is highly unlikely that you will every need to get to the level of detail of the
ASN.1 definitions when doing directory synchronization. You do need to have a
basic understanding of object classes and attributes. And if you are using a
proprietary directory that “supports LDAP,” as opposed to a true LDAP directory,
it is very important to know what proprietary attributes get mapped by the LDAP
service to which LDAP standard attributes.
8.3.4 Attribute and record mapping
For a conversation to be meaningful to all participants, everyone involved must
understand what is being communicated. But you can probably count on the data
sources representing their data content in different ways. One system might
represent a telephone number as textual information, including the dashes and
parentheses used to make the number easier to read. Another system might
store it as numerical data.
If these two systems are to communicate about this data, then the information
must be translated during the conversation. Furthermore, the information in one
source might not be complete, and might need to be augmented with attributes
from other data sources. In addition, only parts of the data in the flow might be
relevant to some of the data sources and targets.
Choosing which fields or attributes are to be handled in a dataflow or passed on
to a data source, as well as how each connected system refers to and represents
this information, is called attribute mapping. The processing required to
“translate” the data from one native syntax into another directory’s native syntax
is called data transformation.
The method used to match source and target directory entries is known as
record mapping. Record mapping in terms of directory synchronization is the
means by which we match a user’s entry in directory “A” to his entry in directory
“B.” Based on our experience, this is often a daunting task. The challenge is
inconsistency in the names used in the different directories. For example,
“James L Smith” in the human resource directory is “Jim Smith” in the corporate
e-mail directory, and “JLSmith” in the network operating system. Thus most
organizations have what are known as multiple identities for the users: more
than one name representation for the same person (or group of people).
Chapter 8. Directory strategies 321