Transcript Name Services

Name Services
Johanna Hultin
Carina Höglund
Name services
 Introduction
 General Terms
 Name Services
 Name Space
 Name Resolution
 Caching
Introduction
Names
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Fundamental in distributed systems
Facilitates communication and resource sharing
A consistent naming system is required
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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
www.facebook.com
/etc/passwd
URL
Internet Domain Name
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
Ex: Reaching a file from URL address
 Domain Name
Server
Name service used by
webbrowsers to
interpret URL and
e-mail addresses
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!