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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
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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 URL www.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
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