LDAP (3)
In 1988 OSI defined a powerful X.500 global directory service OSI based; OSI is abandoned now
- X.500 standard defines hierarchical directory structure for administrative domains; general purpose directory service
- difficult, complex implementation, lack of products on the market
- reading and querying operations (searching) are presumed to occur more frequently than additions and modifications
- based on hierarchical structure of names rather than a relational architectural model
- Database: DIT (Directory Information Tree) is composed of data objects; object are identified in similar way as in MIB (Management Information Base) databases (example: user1.npac.su.us)
- DAP - Directory Access Protocol for client to server queries
- DSP - Directory Service Protocol for server to server queries