Name Services

Johanna Hultin

Carina Höglund

Name services

Introduction

General Terms

Name Services

Name Space

Name Resolution

Caching

Introduction

Names

Fundamental in distributed systems Facilitates communication and resource sharing A consistent naming system is required

Adresses: locations of objects, not identifiers

Introduction

Name service

Translates a human-readable name into a system-internal identifier

Ex human readable names: http://www.facebook.com URLwww.facebook.com Internet Domain Name/etc/passwd File name

Ex system-internal name:

123.25.7.34 IP address

General terms

Resolution Translation of a name into data

Binding Association between an object and a name

Context Set of bindings

Attributes: value of property of an object Ex: address

Ex Name Service: Domain Name System (DNS)

Name Service

A name service stores the collection of one or more naming contexts

Major operation: Look at attributes of a given name Other operations required

Adding/deleting bindings Listing bound names Adding/deleting context

Name management is separated from other services Unification: use the same naming scheme Integration: Openness

Domain Name Server Name service used by

webbrowsers to interpret URL and

e-mail addresses

Ex: Reaching a file from URL address

Name spaces

All valid names recognized in a particular service Ex: URL in DNS

DNS name space Hierarchical structure

Alias Possible to use a simple name instead of a complicated one

Provides for transparency. www.example.net is an alias for www.johanna.example.net

Name Resolution

Iterative navigation DNS

Caching

Holds names that has previously been looked up

Consulted during name resolution

Availability

Questions?

Thanks for listening!