3. What is Distributed System?
A distributed system:
Multiple connected CPUs working
together
A collection of independent computers
that appears to its users as a single
coherent system. ~Tanenbaum
Distributed program running on it.
Distributed programming is used to
write Distributed program.
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3/3/2014
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4. Contd…
What is Distributed System?
Distributed computing is field of
computer science where we learn about
It is easy to expand and scale.
Computer networks where individual
computers were physically distributed
within some geographical area.
Main goal solve large computational
problem.
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3/3/2014
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6. Why need, When use
Much better performance ratio
Resource sharing
Enhanced performance -tasks can be
executed concurrently; load distribution
to reduce response time
Higher reliability - data replication
Easier modular expansion -- hardware and
software resources can be easily added
without replacing existing resources
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3/3/2014
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7. Differentiation with Parallel
Systems
No need of shared memory
Communication via message passing
No need of homogeneity
DS consists of different types of
hardware and software.
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9. Models
Tanenbaum and Renesse classified
distributed systems into three
broad categories
1. Minicomputer Model
2. Workstation Model
3. Processor Pool Model
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10. Types
Distributed Computing System
Distributed Information Systms
Distributed Pervasive systems
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11. Example
World Wide Web (WWW) is the biggest
example of distributed system.
Others are
The Internet.
An Intranet which is a portion of the
internet managed by an organization.
Multimedia production house
Space research
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12. What is Operating System?
An operating system (OS) is:
a software layer to abstract away and
manage details of hardware resources
a set of utilities to simplify application
development.
Applications
OS
Hardware
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13. Evolution of OS
OS generation can be classified in four
type. Following is the types with their
goals:1.
2.
3.
4.
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Centralized OS ~ Resource Management
Network OS ~ Resource Sharing
Distributed OS ~ Transparency
Cooperative OS ~automaticity
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14. Distributed Operating System?
A distributed operating system is one
that looks to its users like an ordinary
centralized operating system but runs
on multiple, independent central
processing units (CPUs).
The key concept here is transparency.
A distributed OS provides the essential
services and functionality required of
an OS.
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19. NOS vs DOS
NOS are considered here to be those which
provide support for networking and
remote resource access, often by a
separate layer of software on top of a
conventional OS.
DOS strive for a high degree of
transparency and often support data and
process migration. Users normally do not
distinguish local resources from remote
resources.
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21. Examples
AMOEBA OS ~Andrew S. Tanenbaum
Solaris OS ~SUN Microsystem
MOSIX ~Hebrew University of Jerusalem
(Professor Amnon)
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22. Have Any Question?
Just Ask!
Post Query On
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Distributed systems used for high-performance computing task
Usually, people argue about the differences between distributed and parallel systems.The same system may be characterized as “parallel” and “distributed” at the same time.A main difference is that in distributed systems, there is no need of a shared memory, since the nodes communicate via message passing.Another difference is that there is no homogeneity. A distributed system consists of different types of hardware and software.
resource sharing– the possibility of using available resources any where openness– an open system can be extended and improved incrementally scalability– serve more users, provide shorter response times fault tolerance– maintain availability even when individual components fail heterogeneity– network and hardware, operating system, programminglanguages, implementations by different developers
Distributed Computing Systems Used for high performance computing tasks Cluster computing systems Grid computing systemsDistributed Information Systems Systems mainly for management and integration ofbusiness functions Transaction processing systems Enterprise Application IntegrationDistributed Pervasive Systems Mobile and embedded systems Home systems Sensor networks
CharacteristicsProcess Management memory management I/O management file Management.Remote access information exchange network browsing.Global view of file system, time, security, computational power.Open and cooperative distributed applications.
In other words, the use of multiple processors should be invisible (transparent) to the user. Another way of expressing thesame idea is to say that the user views the system as a “virtual uniprocessor,” not as a collection of distinct machines.*Transparency is one of the advantages of the Distributed Operating System, where it refers to the physical placement of data (files,relations,.etc) is not known to the user.
Access transparency - accessing both local and remote system objects ina uniform way.• Location transparency - no awareness of object locations. Sometimescalled name transparency.• Migration transparency - ability to move an object to a different locationwithout changing its name; also called location independence.• Concurrency transparency - allow the sharing of objects withoutinterference.• Replication transparency - consistency of multiple instances (orpartitioning) of files and data.• Parallelism transparency - parallel activities without users knowing how,when and where.• Failure transparency - fault tolerance.• Performance transparency - attempts to achieve a consistent andpredictable performance level even with changes of the system structure orload distribution.• Size transparency
NOS 2Tier ArchitectureDOS n Tier ArchitectureNOS use TCP/IPDOS use IPC
AMOEBA : The Python programming language was originally developed for this platform. Use FLIP Fast Local Internet Protocol