What's a Naming System or Service?
A naming system associates names with addresses. A phone book is a perfect example of a naming system that associate people's names with phone numbers and addresses. Naming systems are used in computing to make it easier for user to locate and utilize software that is addressable. A software system that exposes a naming system to other software is called a naming service.
A prefect example of a naming service is the Domain Name System (DNS) used by everyone on the World Wide Web. Internet Protocol (IP) addresses are made up of a series of digits separated by "dots" ('.'). The address of jGuru.com, for example, is 220.127.116.11. IP address are great for routing messages among the millions of computers on the Internet, but its not very user friendly. The DNS associates names with these IP addresses so that it's easier for humans to remember addresses of their favorite sites and access them on the Internet.
Naming services are common place in computing. The OS file system on a computer is a type of naming service that associates the addresses of data blocks on a disk drive with file and directory names. Network file systems are also naming services and some, like NIS+ and Novell Netware are an advanced naming service called a directory service.