Directory Server serves directory data to standards compliant LDAP and DSML applications. Directory Server stores the data in customized, binary tree databases, allowing quick searches even for large data sets.
Directories are object oriented databases. Directories organize their data objects, called entries, into a directory information tree, often called a DIT. Each entry is identified by a distinguished name, such as uid=bjensen,ou=people,dc=example,dc=com. The distinguished name identifies where the entry is located in the directory information tree. For example, uid=bjensen,ou=people,dc=example,dc=com is a user entry for Barbara Jensen on the ou=people branch of the dc=example,dc=com part of the tree.
Each directory entry has attributes. For entries that concern people, these attributes may reflect names, phone numbers, and email addresses, for example. An attribute has at least one type name, which is the name of the attribute. For example, people entries can have an attribute surname, which can also be called by the shorter name sn. Attributes can also have one or more values. For example, if Barbara Jensen marries Quentin Cubbins, and takes Quentin's surname, her entry could have sn: Jensen and sn: Cubbins.
Directories are designed to be fast when looking up entries based on the values of their attributes. An example query might be, “Find all the entries under dc=example,dc=com with surname Jensen.” This fast lookup capability makes directories well suited for applications where you store information that must be read often. Directories are therefore good data stores for telephone and email information. Directories are also good for handling authentication credentials, identity information, and application configuration data.
Directory Server is also designed to handle high update rates as the information in the directory changes. Today, the size of many directory deployments mean that handling updates well can be as important as handling lookups.
Directory Server supports many directory related standards and RFCs. Directory Server allows fast data replication across the network for high availability. Directory Server lets you configure servers comprehensively without restarting them. Furthermore, Directory Server gives you extensive control over access to directory data.
The list of Directory Server features is too long to cover in a short introduction. Sun Java System Directory Server Enterprise Edition 6.0 Evaluation Guide includes a more extensive list. The other chapters in this part of this Reference help you to understand many of the features in detail.