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: URL Domain Name /etc/passwdFile name Ex system-internal name: 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 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. is an alias for

Name Resolution Iterative navigation  DNS

Caching Holds names that has previously been looked up Consulted during name resolution Availability

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