The Case for Proactive Directory Services Fabi

1
The Case for Proactive Directory ServicesFabián
E. Bustamante - Patrick Widener - Karsten
Schwanfabianb,pmw,schwan_at_cc.gatech.eduwww.cc.g
atech.edu/systems/projects/PDSCenter for
Experimental Research in Computer SystemsCollege
of ComputingGeorgia Institute of Technology

• Research Context
• New infrastructure layers pooling together widely
  distributed resources and services
• Computational Grids
• Pervasive Computing
• Directory service key component for such
  infrastructures
• Metacomputing Directory Service (Globus)
• Intentional Naming System (Oxygen)
• Secure Directory Service (Ninja)

• Directory services
• Act as the glue that holds distributed
  infrastructure together
• Provide information about different objects in
  the environment
• Requirements
• Support sophisticated object descriptions and
  query patterns
• Operate in highly dynamic environments
• Scale to an increasingly large number of objects

• The Problem
• Classic directory services
• Designed for fairly static environments where
  updates are rare
• Rely on exclusive inactive interfaces
• Problems with inactive interfaces
• Hinder service scalability Client, server, and
  network
• Indirectly restrict the behavior of potential
  applications1
• 1.W. Smith et Al., An Evaluation of Alternative
  Designs for a Grid Information Service, In
  Proceedings of the HPDC9, Pittsburg, Pa, August,
  2000.

Evaluating Passive and Active Interfaces Clients
need to be aware of updates to entities but have
no knowledge of the pattern of those
updates. Restricted to a passive interface a
client can poll the directory for updates at some
frequency its degree of consistency depends on
how closely its polling pattern matches the
update pattern of the entity owner. With an
active interface the client can choose to
remain fully consistent, independently of the
update pattern of the entitys owner.

• Related Work
• Directory Services
• MDS, INS, SDS, Globes Directory Service, Huang
  and Steenkistes Extended-SLP, Active Names,
• Publish/Subscribe Systems
• Gryphon, Siena, JEDI, SEDA,
• Cache Consistency (in Web, WAN FS, )
• Future Work
• Security
• Evaluation approaches
• More applications,

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