Questions on Distributed Systems
DISTRIBUTED SYSTEMS
ASSIGNMENT AND CAT QUESTIONS
QUESTION 1
a) Give four examples of resources that may be shared in a distributed system.( 4marks)
Possible examples are: hardware resources (disk space, printers, memory,
CPU power, etc) and data/software resources (distributed objects, web-pages,
Databases,).
b) What is the role of middleware in a distributed system?
To enhance the distribution transparency that is missing in network operating systems. In other words, middleware aims at improving the single-system view that a distributed system should have (4marks)
c) Explain the role of the data level in three-tired client/server architecture. (6marks)
Many client-server applications can be constructed from roughly three different pieces: a user interface, a part that operates on a database or file system, and a middle part that generally contains the core functionality of an application.
This middle part is logically placed at the processing level.
For example, in an Internet search engine, the processing level program transforms user’s string of keywords into one or more database queries, ranks the results into a list and transforms the list into a series of HTML pages.
d) Classify the following protocols: IP, TCP, and HTTP according to the ISO OSI classification. (3marks)
e) Why is it sometimes so hard to hide the occurrence and recovery from failures in a distributed system? (4marks)
f) Why are transport-level communication services often inappropriate for building distributed applications? (3marks)
QUESTION 2
a) Imagine a Web server that maintains a table in which client IP addresses are mapped to the most recently accessed Web pages. When a client connects to the server, the server looks up the client in its table, and if found, returns the registered page. In your opinion, is this server stateful or stateless? Present an argument to support
ASSIGNMENT AND CAT QUESTIONS
QUESTION 1
a) Give four examples of resources that may be shared in a distributed system.( 4marks)
Possible examples are: hardware resources (disk space, printers, memory,
CPU power, etc) and data/software resources (distributed objects, web-pages,
Databases,).
b) What is the role of middleware in a distributed system?
To enhance the distribution transparency that is missing in network operating systems. In other words, middleware aims at improving the single-system view that a distributed system should have (4marks)
c) Explain the role of the data level in three-tired client/server architecture. (6marks)
Many client-server applications can be constructed from roughly three different pieces: a user interface, a part that operates on a database or file system, and a middle part that generally contains the core functionality of an application.
This middle part is logically placed at the processing level.
For example, in an Internet search engine, the processing level program transforms user’s string of keywords into one or more database queries, ranks the results into a list and transforms the list into a series of HTML pages.
d) Classify the following protocols: IP, TCP, and HTTP according to the ISO OSI classification. (3marks)
e) Why is it sometimes so hard to hide the occurrence and recovery from failures in a distributed system? (4marks)
f) Why are transport-level communication services often inappropriate for building distributed applications? (3marks)
QUESTION 2
a) Imagine a Web server that maintains a table in which client IP addresses are mapped to the most recently accessed Web pages. When a client connects to the server, the server looks up the client in its table, and if found, returns the registered page. In your opinion, is this server stateful or stateless? Present an argument to support