Doubt about Mock Exams Questions

[Gowher Naik]

Question1
Which statements describe Publish-Subscribe Messaging and which describe Point To Point Messaging?

A Publish-Subscribe Messaging is a message queue system.
B Publish-Subscribe Messaging = One sender and one receiver.
C Point To Point Messaging = N senders and one receiver.
D Publish-Subscribe Messaging = 1 sender and n receivers.
E Point To Point Messaging is a message queue system.
F Point To Point Messaging = One sender and one receiver.

According mock exam Choices D and F are correct.

My doubt is Why option E is not correct?

Question2
Which statement are True?

A In 3 tier system the client is know as thin client.
B In 2 tier if PL/SQL stored procedures is coded at back end then client is known as thin client.
C In 2 tier if PL/SQL stored procedures is not coded at back end then client is known as Fat client.

According me all three(A,B,C) are True

Please help.
Thanks

[Juan Pablo Crossley]

I think its because it really does not describe the behavior, I mean, if you say: "A car is an automobile" the people will be its different if you say: "A car is a transportation machine to carry out people inside"...

[Rodrigo Malara]

I would also say that the word queue may imply that messages sent are queued if the receiver is not available, which is not true for Point-to-Point messaging but it is particularly true for Publish-Subscribe messaging.
In that way, for some readers, option E may sound wrong.

About the second question:
I would say that only option A is true.

Option B doesn't seems ok to me because even if stored procedures are dealing with most of business logic, you will certainly have business logic in the application (real world ones), which would need to ported to another app if you need to change the UI. On three tier the idea would be being able to change the View tier and keep the Business Logic tier untouched (by using a tier of Business Delegates, for example).

Option C isn't ok for me because stored procedures don't make sense to be inside application code because they should be 'stored' in the database back-end.

Any other thoughts? Please correct me if I'm wrong.

[Ådne Brunborg]

Re: Question 2:

A 2-tier architecture is any architecture with a user interface on the client, and the database on the server. The business logic can be on the client (fat client) or on the server (thin client).

Wether or not PL/SQL stored procedures are used is completely irrelevant to wether the client is fat or thin.