CHAPTER 2.2
TRANSPARENCY
By,
Naga Manojna Chintapalli.
nchintapalli1@student.gsu.edu
OVERVIEW
•
•
•
•
•
•
•
•
Evolution of Modern Operating systems
Distributed Operating System
Goals of DOS
Definition of Transparency
Types of transparency and their categorizations
Distributed System issues & Transparencies
DOS projects
References
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
DISTRIBUTED OPERATING SYSTEM
• A collection of independent computers that
appear to the system users as a single
computer presenting a transparent view of
a multiple computer system with distributed
resources and control.
GOALS OF DOS
• Efficiency
• Flexibility
• Consistency
• Robustness
TRANSPARENCY
• “Is defined as the concealment from the
user and the application programmer of the
separation of components in a DS, so that
the system is perceived as a whole rather
than as a collection of independent
components”
TRANSPARENCY (CONTD.,)
• Goal motivated by the desire to hide all
irrelevant system-dependent details from the
user, whenever possible.
• It is more important in distributed systems due to
higher implementation complexities.
• Shielding the system-dependent information
from the users is a trade-off between simplicity
and effectiveness.
TYPES OF TRANSPARENCY
• We have 10 types of transparencies. Let us see
them in detail.
ACCESS TRANSPARENCY
• Access transparency - accessing both local and remote
system objects in a uniform way.
LOCATION TRANSPARENCY
• Location transparency - no awareness of object
locations. Sometimes called name transparency.
• Users of a Distributed System are not aware where a
resource is physically located.
• The resources are referred by logical names.
• Example: area codes
MIGRATION TRANSPARENCY
• Migration transparency - ability to move an object to a
different location without changing its name; also called
location independence.
CONCURRENCY TRANSPARENCY
• Concurrency transparency - allow the sharing of
objects without interference.
• Multiple users sharing a resource without any
interference.
• It is similar to the time sharing concept.
REPLICATION TRANSPARENCY
• Replication transparency - consistency of multiple
instances (or partitioning) of files and data
PARALLELISM TRANSPARENCY
• Parallelism transparency - parallel activities without
users knowing how, when and where they are taking
place.
FAILURE TRANSPARENCY
• Failure transparency - fault tolerance.
• Despite any failures in the system the task needs to be
completed successfully i.e., it ensures graceful
performance and minimum damages to the user.
PERFORMANCE TRANSPARENCY
• Performance transparency - attempts to achieve a
consistent and predictable performance level even with
changes of the system structure or load distribution.
SIZE TRANSPARENCY
• Size transparency - modularity and scalability.
• The system can expand in size without the
knowledge of the user. It pertains to the
incremental growth of the hardware.
REVISION TRANSPARENCY
• Revision transparency - vertical growth of the
system
• This transparency refers to the software
revisions which are not visible to the users.
CATEGORIZATION OF
TRANSPARENCIES
• Transparencies can be categorized based on the
goals of the distributed operating systems.
Concurrency Transparency
Parallelism Transparency
Performance Transparency
Efficiency
Failure Transparency
Replication Transparency
Size Transparency
Revision Transparency
Robustness
Access Transparency
Location Transparency
Migration Transparency
Size Transparency
Revision Transparency
Flexibility
Access Transparency
Replication Transparency
Performance Transparency
Consistency
DISTRIBUTED SYSTEM ISSUES & TRANSPARENCIES
PROJECTS
Example of projects based on distributed operating systems is
•
E1
 E1 is a distributed operating system project, based on the following concepts:
• object replication
• component model support
• Persistence
 It Provides efficient access to the resources of computer network, implements a
convenient programming model, isolating software developers from the intrinsic
complexity of asynchronous distributed environment.
 http://www.cs.utah.edu/~aburtsev/doc/e1_nicta_talk.pdf refer the link to know
more about this project.
REFERENCES
[1] A. S. Tanenbaum, “Distributed Operating Systems”, Prentice Hall, pp.2225,2001.
[2] Y. Lu, “Distributed Operating Systems”, UNL.
[3 ]R. Chow, T. Johnson, “Distributed Operating Systems & Algorithms”, Addison
Weley, pp.29-32,1999.
[4] B. Karp, “RPC & Transparency”,UCL Computer Science,2006.
[5] Parallel and Distributed Operating System Group, MIT http://project-iris.net/
[6] IRIS: Infrastructure for Resilient Internet Systems http://project-iris.net/
[7] http://en.wikipedia.org/wiki/Transparency_(Distributed Systems)
THANK YOU