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Transparency. Wang, Yang ywang39@student.gsu.edu. OUTLINE. Review Transparencies in DOS Categorization Degree of Transparency Summary Reference. Review. Evolution of Modern Operating Systems What is DOS? Goals of DOS. Evolution of Modern Operating Systems.

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Transparency

Transparency

Wang, Yang

ywang39@student.gsu.edu


Outline
OUTLINE

  • Review

  • Transparencies in DOS

  • Categorization

  • Degree of Transparency

  • Summary

  • Reference


Review
Review

  • Evolution of Modern Operating Systems

  • What is DOS?

  • Goals of DOS


Evolution of modern operating systems
Evolution of Modern Operating Systems

  • 1st Generation: Centralized Operating System

  • 2nd Generation: Network Operating System

  • 3rd Generation: Distributed Operating System

  • 4th Generation: Cooperative autonomous System


Definition of dos
Definition of DOS

  • We define a DOS as an integration of system services ,presenting a transparent view of a multiple computer system with distributed resources and control.


Goals of dos
Goals of DOS

  • Efficiency

  • Flexibility

  • Consistency

  • Robustness


Outline1
OUTLINE

  • Review

  • Transparencies in DOS

  • Categorization

  • Degree of Transparency

  • Reference


Definition of transparency in dos
Definition of Transparency in DOS

  • Concealment from the user and the application programmer of the separation of components in a distributed system, so that the system is perceived as a whole than rather as a collection of independent components.


Compare
Compare

  • In software engineering, it is also considered good practice to develop or use abstraction layers for database access, so that the same application will work with different databases; here, the abstraction layer allows other parts of the program to access the database transparently.

  • In object-oriented programming, transparency is facilitated through the use of interfaces that hide actual implementations through different classes.


Access transparency
Access Transparency

  • The ability to access both local and remote system objects in a uniform way.

  • Example: NFS


Location transparency
Location Transparency

  • Name Transparency

  • Users have no awareness of object locations (physical location)

  • "The network is the computer"


Migration transparency
Migration Transparency

  • Resources could be free to move from one location to another without having their names changed

  • Example: Cell phone & BSC, roaming


Example
Example

  • Communication with your friends….

  • Access

  • Location

  • Migration

  • Access location Migration are interrelated


Failure transparency
Failure Transparency

  • Applications should be able to complete their task despite failures occurring in certain parts of the system.

  • Fault tolerance

  • Example: backup database


Replication transparency
Replication Transparency

  • The system is free to make additional copies of files and other resources (for purpose of performance and/or reliability), without the users noticing.

  • Consistency between copies (DNS master ,slave)


Concurrency transparency
Concurrency Transparency

  • The users will not notice the existence of other users in the system (even if they access the same resources)

  • Similar to time-sharing system


Performance transparency
Performance Transparency

  • Load variation should not lead to performance degradation. This could be achieved by automatic reconfiguration as response to changes of the load.


Parallelism transparency
Parallelism Transparency

  • This permits parallel activities without users knowing how, where, and when these activities are carried out by the systems.


Scaling size transparency
Scaling (Size) Transparency

  • Can expand in scale(incremental growth) without change to system's structure or application algorithms.(Hardware)


Revision transparency
Revision Transparency

  • This refers to the vertical growth of systems as opposed to the horizontal growth as in scalable transparency. Revision of software not visible to users.


Security transparency
Security transparency

  • Negotiation of cryptographically secure access of resources must require a minimum of user intervention, or users will circumvent the security in preference of productivity.


Persistence transparency
Persistence Transparency

  • Hide whether a (software) resource is in memory or on disk.


Relocation transparency
Relocation transparency

  • Should a resource move while in use, this should not be noticeable to the end user.


Outline2
OUTLINE

  • Review

  • Transparencies in DOS

  • Categorization

  • Degree of Transparencies

  • Summary

  • Reference


Goal flexibility
Goal: Flexibility

  • Access

    location

    migration

    size

    revision


Goal consistency
Goal: Consistency

  • Access

    Replication

    Performance


Goal robustness
Goal: Robustness

  • failure

    replication

    size

    revision


Goal efficiency
Goal:Efficiency

  • Concurrency

    Parallelism

    Performance


Outline3
OUTLINE

  • Review

  • Transparencies in DOS

  • Classification

  • Degree of Transparencies

  • Summary

  • Reference


Degree
Degree

  • Distribution transparency is generally preferable, but not always a good idea:

    • It is undesirable to hide the location of the printer from its users


Trade off
Trade-off

  • Shielding the system-dependent information from the users is basically a trade-off.


Outline4
OUTLINE

  • Review

  • Transparencies in DOS

  • Classification

  • Degree of Transparencies

  • Summary

  • Reference


Summary
Summary

What is Transparency?

Categorization

Trade-off


Some related articles
Some related articles

[1] Application-Transparent Fault Tolerance in Distributed Systems, Thomas Becker

[2]On the Structuring of Distributed Systems: The argument for mobility, Todd.

[3]Name Transparency in very large scale Distributed file systems, Richard G. Guy et al

[3]http://en.wikipedia.org/wiki/Transparency_(computing)


Thanks and apologize
Thanks and Apologize

  • Thank you!

  • 谢谢!

  • shukria


References
References

[1]A. S. Tanenbaum, “Distributed Operating Systems”,Prentice Hall, pp.22-25.

[2]R. Chow,T. Johnson, “Distributed Operating Systems & Algorithms”, Addison Weley, pp.29-32.

[3]J. Wein, “Parallel & Distributed Systems”

[4]B. Karp, “RPC & Transparency”,UCL Computer Science,2006

[5]Y. Lu,”Distributed Operating Systems”,UNL

[6]J. Holliday,”Distributed Computing”,SCU

[7]B. Karp, S. Hailes,”Distributed Systems & Security:An Introduction,UCL Computer Science,2006