Basic Concepts of LDAP

Entry
An Entry is a collection of attributes identified by its DN (distinguished name). A DN is unique in all the tree and therefore it identifies clearly the entrance to which refers. As example: CN=Alex O=CHAOSDIMENSION C=ES must identify to the object of common name Álexthat is in organization CHAOSDIMENSIONánd country is ÉS(Spain). A RDN(names distinguished relative) is a part of the DN, in a way that concatenating the RDNs they give as result the DN. Of the previous example CN=Alex is a RDN.

Object Class
A Object Class is a special attribute (ObjectClass) that defines attributes that are required and allowed in an entry. The values of the Objects Classes are defined in the schema. All the entrances must have a ObjectClass attribute. It isnt allowed to add attributes to the entries that arent allowed by definitions of the Objects Classes of the entry.

Attrib
An Attribute is a type with one or more values associated. It is identified by a OID (object identifier). The attribute type indicates if can have more of a value of this attribute in an entry, the values that can have and how they can be searched.

Schema
A Schema is a collection of definitions of types of attributes, Objects Classes and information that the server use to do the searches, to introduce values in an attribute, and to allow operations to add or to modify.

To create a search, we must consider several important parameters:

Filter

Base Object

Un DN que sera a partir del cual realizaremos la busqueda.

Scope

It can have several values.

base

it will only search in the level base.

sub

it will make recursiva search by all the tree from the level base

one

search a level below the level base.

Size Limit

It restricts the number of entries given back as result of a search.

Time Limit

It restricts the execution maximum time of a search.

Filter

A chain that defines the conditions that must be completed to find an entry.

The filters can be concatenated with ' and', ' or' and ' not' to create more complex filters. For example a filter with base O=CHAOSDIMENSION, C=ES, scope base and filter (CN=Alex) would find the entry CN=Alex , O=CHAOSDIMENSION, C=ES.