Define Distributed Operating System, Network Operating System and Middle-ware? Differentiate between DOS, NOS and Middle-ware? Define the goals of each? ???

1. Assignment
Distributed Computing
Submitted To
Ms.Rabia Latif
Submitted By
Abdul-rehman Aslam
Class
BSSE 7Th
Roll No
9998
NATIONAL UNIVERSITY OF MODERN LANGUAGES
ISLAMABAD
13, December 2012
3|Page

2. Question:-
Define Distributed Operating System, Network Operating
System and Middle-ware? Differentiate between DOS,
NOS and Middle-ware? Define the goals of each?
Distributed Operating System:
Distributed Means Data is Stored and Processed on Multiple Locations.
Or
An operating system which manages a collection of independent computers and
makes them appear to the users of the system as a single computer.
Network Operating System:
Network operating system is also referred to as the Dialoguer. It is the software
that runs on a server and enables the server to manage data, users, groups,
security, applications, and other networking functions. The most popular network
operating systems are
 Microsoft Windows Server 2003
 Microsoft Windows Server 2008
 Unix
 Linux
 Mac OS X
 Novell NetWare
 BSD
4

3. Middle-ware:
Middleware is computer software that provides services to software applications
beyond those available from the operating system. It can be described as
"software glue".
Or
The glue which connects objects which are distributed across multiple
heterogeneous computer systems.
5

4. Difference between DOS, NOS and Middleware:
DOS NOS Middleware
Tightly-coupled operating Loosely-coupled Additional layer atop of
system for multi- operating system for NOS implementing
processors and heterogeneous multi- general-purpose services
homogeneous computers (LAN and
multi-computers. WAN)
Follow n tier Client server Follow 2 tier Client server
architecture architecture
Distributed OS
Item Network Middleware-
Multiproc. Multicomp. OS based OS
Degree of transparency Very High High Low High
Same OS on all nodes Yes Yes No No
Number of copies of OS 1 N N N
Basis for communication Shared Messages Files Model specific
memory
Resource management Global, Global, Per node Per node
central distributed
6

5. Scalability No Moderately Yes Varies
Openness Closed Closed Open Open
Goals of Distributed Operating System:
The main goal of distributed operating systems is the following.
 Hide and manage hardware resources.
 Transparent performance
 Scalability
 Fault tolerance
 Consistency
Goals of Network Operating System:
The main goals of network operating systems are the following.
 Offer local services to remote clients
Goals of Middleware:
The goals of middleware are
 Provide distribution transparency
 Integrate existing component into a distributed system
 Resolve heterogeneity
7

6. 8

7. 8

8. 8