Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved DISTRIBUTED SYSTEMS Principles and Paradigms Second Edition ANDREW S. TANENBAUM MAARTEN VAN STEEN Chapter 5/B Naming Modified by Dr. Gheith Abandah

Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved Overview 5.1 Names, Identifiers, and Addresses 5.2 Flat Naming Simple Solutions Home-based Approaches Distributed Hash Tables Hierarchical Approaches 5.3 Structured Naming Name Spaces Name Resolution The Implementation of a Name Space Example: The Domain Name System 5.4 Attribute-based Naming Directory Services Hierarchical Implementations: LDAP Decentralized Implementations

Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved Attribute-based Naming

Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved Directory Services RDF: Resource Description Framework Database of (reserouce, attribute, value) Example: (Person, Name, John)

Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved Hierarchical Implementations: LDAP (1) Light-weight directory access protocol: used in MS Active Directory and X.500. The figure shows part of the directory information tree (DIT) which contains the cs.vu.nl domain.

Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved Hierarchical Implementations: LDAP (2) A simple example of an LDAP directory entry using LDAP naming conventions. /C=NL/O=Vrije Universiteit/OU= comp Sc. Is globally unique name (relative distinguished name (RDN)) of nl.vu.cs

Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved Hierarchical Implementations: LDAP (3) Two directory entries having Host_Name as RDN. Search for. /C=NL/O=Vrije Universiteit/OU= comp Sc/CN=Main server returns star and zephyr

Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved Decentralized Implementations Peer-to-peer systems often use decentralized attribute-based naming systems. The (attribute, value) pairs are distributed. In decentralized implementations, it is important to do search efficiently. Solutions include: Distributed hash tables Semantic overlay networks