Name

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Name Directory Services

• Yang Wang

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Outline

• Why and What?
• Some important Terms.
• How to do?
• History and Implementation.
• Example and Experiment
• References

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Why We Need It?

• Making a request to a service or accessing an
  object by means of inter-process communication
  requires that must one first locate the service
  or object.1
• Look-up operations.
• 1.Randy Chow,Theodore Johnson, Distributed
  Operating Systems Algorithms, 1998

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What Is It?

• Name Service or Directory Service Describing how
  a named object can be addressed and subsequently
  located by using its address.1

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Resolution process

• The operation of locating an object.
• Two stages
• Name resolution maps names to logical addresses.
  (who the object is.)
• Address resolution that maps logical addresses
  to network routes.(where the object can be
  found.)1

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Purpose

• Enable user to reference network resources with
  short names instead of real addresses.
• Locate object by attributes.
• Provide a layer of transparency so that the
  network resources can be managed independently.3

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Outline

• Why and What?
• Some important Terms.
• How to do?
• History and Implementation.
• Example and Experiment
• References

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Name Space

• Object attributes
• Focus on name and address.
• Collection of names ,with their corresponding
  attributes and addresses.

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Name Structures

• 1.flat structure ltattributesgt Physical
• 2.hierachical ltname,attributes,addressgt
• (DNS)
  Organizational
• 3.structure-free ltname,type,attributes,addressgt
• 
  Functional

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Outline

• Why and What?
• Some important Terms.
• How to do?
• History and Implementation.
• Example and Experiment
• References

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Storage model(x.500)

• X.500 DIB directory information base.
• DIT Directory Information Tree.
• Naming domain a sub-name space for which there
  is a single administrative authority for name
  management.
• Naming Context basic units for distributing the
  info base to Directory Service Agents.
• DSA The server for the name service.
• DUA directory user agent1

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Resulotion

• DSA
• DUA initiate the resolution.
• 3 kinds

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Enhancement

• Caching (DNS)
• Replication

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Outline

• Why and What?
• Some important Terms.
• How to do?
• History and Implementation.
• Example and Experiment
• References

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History of Name Service

• In 60s and early in 70s, hosts file and other
  files used to store parameters and information
  for locating.
• Drawbacks modify frequently, larger and
  larger.7
• 7.Larry Gouthier, 1998, Directory-enabled
  computing the directory's expanding role.

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hosts
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DNS

• Domain Name Service replaced.
• Dynamic and based on server.
• The first standard directory and the most
  successful one.
• At the same time, people developed Directory for
  Novel Netware, MS LAN manager,SNA etc.7

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X.500

• DNS only contains host, domain and address, not
  enough.
• In the 80s, X.500
• Drawback too complicated, not support by
  MS.Mainly In unix -gt LDAP7
• 7.Larry Gouthier, 1998, Directory-enabled
  computing the directory's expanding role.

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Implementation

• Active Directory for Windows 2000, Server 2003
• Apple Open Directory in Mac OS X Server
• Novell eDirectory - formerly called Novell
  Directory Services (NDS) for Novell NetWare
  version 4.x-5.x
• OpenLDAP
• Sun Directory Services

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Outline

• Why and What?
• Some important Terms.
• How to do?
• History and Implementation.
• Example and Experiment
• References

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Example

• DNS
• Domain Name System

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Name space
Root Domain
com
org
net
Top-Level Domain
nwtraders
Second-Level Domain
east
south
west
Subdomains
sales
FQDN server1.sales.south.nwtraders.com
Host server1
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DNS Locating Process
Iterative Query
Root Hint (.)
Local DNS Server
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Ask .com
Iterative Query
.com
Ask nwtraders.com
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Recursive query for mail1.nwtraders.com
Iterative Query
172.16.64.11
Authoritative Response
3
Computer1
nwtraders.com
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Some new research

• Load distribution.6
• Web Content distribution.6
• 6. James E Kurose, Keith W.Ross, 2007,Computer
  Networking, 4th Edition.

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References

• 1.Randy Chow,Theodore Johnson, Distributed
  Operating Systems Algorithms, 1998
• 2. Jeff Hodges,"Introduction to Directories and
  LDAP", June 1997
• 3. http//en.wikipedia.org/wiki/Directory_service
  
• 4. http//en.wikipedia.org/wiki/X.500
• 5. http//en.wikipedia.org/wiki/Lightweight_Direct
  ory_Access_Protocol
• 6. James E Kurose, Keith W.Ross, 2007,Computer
  Networking, 4th Edition.

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continue

• 7.Larry Gouthier, 1998, Directory-enabled
  computing the directory's expanding role.
• 8.Akamai 2007,http//www.akamai.com
• 9.RFC 1034, RFC 1035