Technology Questions

In Stop and wait protocol, sender sends one frame, waits until it receives confirmation from the receiver (okay to go ahead), and then sends the next frame.

Open for INPUT, OUTPUT, I-O, EXTEND.

1.INPUT : for read only purpose

2.OUTPUT : for write only purpose

3.EXTEND : for appending records

4.I-O : for read and write(using EXTEND) purpose

- Friend classes are useful when a class wants to hide features from users which are needed only by another, tightly coupled class. 

- Implementation details can be kept safe by providing friend status to a tightly cohesive class.

The finalize method is called by the garbage collector, just before releasing the object’s memory. It is normally advised to release resources held by the object inside the finalize method.

Similarity: Both WHERE and HAVING Clause filters out records based on one or more conditions.

Difference: WHERE Clause can only be applied to a static non-aggregated column whereas HAVING is needed for aggregated columns.

 - When two processes are waiting to update the rows of a table which are locked by another process, the situation is called a deadlock.
 - The reasons for it to happen are:
 * lack of proper row lock commands.
 * Poor design of front-end application
- It reduces the performance of the server severely.
- These locks get automatically released automatically when a commit/rollback operation is performed or any process is killed externally.

EVALUATE can be used in place of the nested IF THEN ELSE statements.

The Big-O notation simply describes how well an algorithm scales or performs in the worst case scenario as the number of elements in a data structure increases. The Big-O notation can also be used to describe other behavior such as memory consumption. Since the collection classes are actually data structures, we usually use the Big-O notation to chose the best implementation to use, based on time, memory and performance. Big-O notation can give a good indication about performance for large amounts of data.