Directory service
lastmod 2018-08-17created 2017-01-021 edits
A directory service (DS) is application software (a set of applications) that stores and organizes information about the users and network resources of a computer network. It helps network administrators give multiple users access to resources. A directory service also acts as an abstraction layer between users and shared resources.
A directory service should not be confused with the directory itself, which is the database holding information about the named objects managed in the directory service. In the X.500 distributed directory service model, one or more namespaces (trees of objects) are used to build a directory service. A directory service provides an interface for accessing the data contained in one or more directory namespaces. The directory service interface acts as a central/common authority and allows the system resources that manage directory data to be securely authenticated.
Like a database, a directory service is highly optimized for "reads" and provides advanced search over the many different attributes that can be associated with objects in the directory. The data stored in a directory is defined by an extensible and modifiable schema. A directory service uses a distributed model to store its information, and this information is usually replicated between directory servers.