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Name & Directory Services

Name & Directory Services. Yang Wang. Outline. Why and What? Some important Terms. How to do? History and Implementation. Example and Experiment References. Why We Need It?.

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Name & Directory Services

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  1. Name & Directory Services Yang Wang

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

  3. 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

  4. What Is It? • Name Service or Directory Service: Describing how a named object can be addressed and subsequently located by using its address.[1]

  5. 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]

  6. 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]

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

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

  9. Name Structures • 1.flat structure <attributes> Physical • 2.hierachical <name,attributes,address> (DNS) Organizational • 3.structure-free <name,type,attributes,address> Functional

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

  11. 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 agent[1]

  12. Resulotion • DSA • DUA initiate the resolution. 3 kinds

  13. Enhancement • Caching (DNS) • Replication

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

  15. 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.

  16. hosts

  17. 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]

  18. 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 -> LDAP[7] • [7].Larry Gouthier, 1998, Directory-enabled computing: the directory's expanding role.

  19. 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

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

  21. Example • DNS • Domain Name System

  22. Name space Root Domain com net org Top-Level Domain nwtraders Second-Level Domain east west south Subdomains sales FQDN: server1.sales.south.nwtraders.com Host: server1

  23. DNSLocating Process Iterative Query Root Hint (.) Local DNS Server 1 Ask .com Iterative Query .com Ask nwtraders.com 2 Recursive query for mail1.nwtraders.com Iterative Query 172.16.64.11 Authoritative Response 3 Computer1 nwtraders.com

  24. Some new research • Load distribution.[6] • Web Content distribution.[6] • [6]. James E Kurose, Keith W.Ross, 2007,Computer Networking, 4th Edition.

  25. 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_Directory_Access_Protocol • 6. James E Kurose, Keith W.Ross, 2007,Computer Networking, 4th Edition.

  26. 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

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