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Naming in Distributed Systems. Lecture # 5. Overview. Pure vs impure names IDs, Addresses,Name Space, Name Resolution Implementation of a Naming Service Case Studies: Telephone System. DNS, SLP(X.500), INS Reading: Jerome, Kaashoek: Chapter 3 - PowerPoint PPT Presentation
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Naming in Distributed Systems
Lecture # 5
Overview
Pure vs impure names IDs, Addresses,Name Space, Name
Resolution Implementation of a Naming Service Case Studies: Telephone System. DNS,
SLP(X.500), INS Reading:
– Jerome, Kaashoek: Chapter 3 – Coulouris: Distributed Systems, Addison Wesley,
Chapter 9
Pure vs impure: What’s in a namePure Names: Uninterpreted string of
bits– Independent of object location or
semanticsImpure Names:
– Encode object semantics and/or locationTelephone Numbers?Descriptions
– Always Search
Naming Scheme
Name Space– Syntax: Different naming conventions– 128.67.34.255– 92-42-5722670– StringBuffer
Naming Resolution AlgorithmValue: DestinationFrequently: Context
Examples of Naming
Telephone System
Numeric name space (length dependant on the size of the city)
Hierarchical Structuring of Names– 92-42-5722670
Hierarchical Name Resolution– Lookup: Directories
Value? Context?
Naming Examples
Naming Variables– Naming convention
Variable Names: start with an alphabetClass Names: start with capitalization
– Value: Address of Memory LocationPointers: Indirection
– Resolution:Symbol Tables
– ContextScoping?
– Dynamic – Lexical: Static
– Hierarchical NamesJava: Derived from directory structure
Naming Examples
DNS Names as Path Names
Root
n1
k1
n2
Root.n1.k1.lums
Root.yahoo
Closure in Naming
Names closed under composition– Using a root
Absolute Vs. Relative Paths– Context
DNS– Mailto: zahoor (from within lums)
Directory– Working directory
Name Resolution
DNS Terminology– Iterative vs. Recursive
Essentially– State management in resolution– Caching– Communication Cost
Iterative
Client-sideName
Resolver
root
edu
pk
lums
www.lums.edu.pk IP number
cs.lums.edu.pk
cs.lums.edu.pk
cs.lums.edu
cs.lums.edu
cs
cs.lums
cs.lums
cs
IP # CS
Recursive
Client-sideName
Resolver
root
edu
pk
lums
www.lums.edu.pk IP number
cs.lums.edu.pk
IP # cscs.lums.edu
cs.lums.edu
cs
cs.lumscs.lums
csIP # CS
Recursive vs iterative
StateCachingCommunication latency
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