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Distributed Systems: Naming Services

Distributed systems require naming services to facilitate communication and resource sharing. Naming services translate human-readable names to system identifiers. They store collections of naming contexts that associate objects with names through bindings. Name resolution lookups translate names to attribute data like addresses. Caching and different resolution approaches like iterative or recursive modes impact performance and network usage. Name spaces define valid name scopes while pointer caches optimize reference lookups.

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Arjuna Krish
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190 views19 pages

Distributed Systems: Naming Services

Distributed systems require naming services to facilitate communication and resource sharing. Naming services translate human-readable names to system identifiers. They store collections of naming contexts that associate objects with names through bindings. Name resolution lookups translate names to attribute data like addresses. Caching and different resolution approaches like iterative or recursive modes impact performance and network usage. Name spaces define valid name scopes while pointer caches optimize reference lookups.

Uploaded by

Arjuna Krish
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Distributed Systems

Naming Services
Naming services
1. Introduction
2. General Terms
3. Name Services
4. Name Space
5. Name Resolution
6. Caching
Introduction
Names

Fundamental in distributed systems


Facilitates communication and resource sharing
A consistent naming system is required

Adresses: locations of objects, not identifiers


Why naming is important?
Names are used to
Share resources
Uniquely identify entities
To refer locations, and so on…

Name resolution allows a process to access


the named entity
Introduction to 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
Naming Entities
Name  string of characters used to refer to
an entity
Entity in DS can be anything, e.g., hosts, printers, disks,
files, mailboxes, web pages, etc
Access Point  To access an entity
Address  name of access point
Access points of an entity may change
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
Implementation of Name
Space
Name Resolution
The process of looking up a name
Closure Mechanism  Knowing how and where to start
name resolution
Mounting  transparent way for name resolution with
different name spaces
Mounted File System  letting a directory node store the
identifier of a directory node from a different name space
(foreign name space)
Mount point  directory node storing the node identifier
Mounting point  directory node in the foreign name
space
Normally the mounting point is root
Name Resolution
Iterative navigation
DNS
Iterative Name Resolution

Advantage
Less burden on name sever
Disadvantage
More communication cost
Recursive Name Resolution

Advantages
Caching result is more effective
Reduced communication cost
Disadvantage
Demands high performance on each name server
Caching
Holds names that has previously been looked
up

Consulted during name resolution

Availability
Pointer Caches (1)
Caching a reference to a directory node of the
lowest-level domain in which an entity will reside
most of the time.
Pointer Caches (2)
A cache entry that needs to be invalidated because
it returns a nonlocal address, while such an
address is available.
THANK YOU

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