Osmania University (OU) 2008 M.C.A Computer Aplications DISTRIBUTED SYSTEMS - Question Paper

UNIT-I
1. (a) discuss the role of middleware in a distributed system.
(b) What is the difference ranging from a vertical distribution and a horizontal?
(c) Sketch the design of a multi threaded server that supports multiple protocols .using, sockets as its transport level interface to the underlying operating system.
2.


(a) Explain what is meant by transparency and provide examples of various kinds of transparency.
(b) What is an open distributed system and what benefits does open ness give ?
(c) Discuss the different approaches to code migration. Also mention the options for code migration.
UNIT-II
3. (a) elaborate the basic approaches for locating mobile entities ?
(b) What is the goal of an election algorithm ? discuss election algorithm
based on the use of a ring.
4. (a) Compare garbage collection that requires the support of reference
counting with that of trace based methods.
(b) discuss any 1 algorithm for achieving distributed mutual exclusion


UNIT-III
5. (a) Why is replication useful ? How does replication relate to scalability ? 3
(b) Can linearizability be implemented for physically distributed data stores ?
(c) For every of the subsequent applications, do you think at-least-once semantics or at most once semantics is best ? explain.

(1) Reading and writing files from a file server.
(2) Compiling a program.
(3) Remote banking.
(d) In two-phase commit protocol, why can blocking never be completely
eliminated, even when the participants elect a new coordinator ?
6. (a) discuss the various consistency models for distributed shared
memory.
(b) Briefly discuss the motion of incremental snapshot.
UNIT-IV
7. (a) What was the design goal of CORBA ? provide an overview of CORBA
system.
(b) In NFS, attributes are cachedlisThg write-through cache coherence policy. Is it necessary to forward all attributes modifications immediately ?
8. (a) Compare DCOM and Globe.
(b) In NFS, what type of security measures can be taken to prevent a malicious client from reclaiming a lock it never was granted when a server enters its grace period ?
(c) Explain how coda solves read-write conflicts on a file that is shared ranging from multiple learners and only a single write.
UNIT - V
9. (a) discuss why the write-invalidate protocol is suitable to maintain
coherence if several updates occur ranging from reads or when a
program exhibits per-node locality of reference.
(b) Classify the load distribution algorithms.
(c) Explain the sender initiated algorithm for load distribution.

10. (a) Contribute your comments on granularity and page replacement
problems in the design of distributed shared memory systems.
(b) discuss briefly about adaptive algorithms for load distribution. ,

Earning:   Approval pending.