Chapter 8

Question 1

What is intern process communication (IPC)

Answer 1

How a cooperating process communicate with another cooperating process and sends information. Process communicate with each other without resorting to shared variables.

Question 2

What is direct inter process communication

Answer 2

The process should have name for sender

Question 3

What is indirect inter process communication

Answer 3

There is no need to put process name

Question 4

What are 2 basic requirements for inter process communication

Answer 4

1. There should be communication link

2. There should be send message and receive message

Question 5

What are 2 implementation of communication link

Answer 5

1. Physical (e.g. shared memory, hardware)

2. Logical (Logical properties)

Question 6

What is meaning of link unidirectional and bidirectional

Answer 6

It means data can transfer either on one side or both sides

Question 7

What is full duplex channel and half duplex channel

Answer 7

Half duplex channel means channel has capability to send data on both directions but at one time. On the other hand, in the full duplex mode of transmission, the communication is bi-directional.

Question 8

Can there be multiple channels for process communication

Answer 8

Yes

Question 9

Does each pair of process may share several communication links in indirect communication

Answer 9

Yes

Question 10

Message passing may be blocking or non-blocking (synchronous or asynchronous)
True or False

Answer 10

True

Question 11

What are 3 possible scenarios of queues of messages or buffering

Answer 11

1. Zero capacity = No message can be queue (example of 2 labor, one man is throwing bricks and other is catching)
2. Bounded capacity = N messages can be queued, fixed size buffering (example of truck that contain bricks and unload bricks in a fixed place)
3. Unbounded capacity = Infinite capacity/length (truck on bricks come and we place it everywhere like on road, neighbors, ground thinking every where is available)

Question 12

What are tools for IPC

Answer 12

• Pipe
• Named pipe (FIFO)
• BSD (Berkley software distribution) Socket
• TLI (transport layer interlink)
• Message queue
• Shared memory

Question 13

What are important system calls of UNIX/Linux

Answer 13

• Pipe (Create a pipe for IPC)
• Read (Read from a pipe)
• Write (Write data to a pipe)
• Close (close/destroy pipe)

Question 14

What is pipe

Answer 14

Pipe is a communication channel through which 2 processes can talk (indirect communication - mailbox based sharing)

Question 15

What open() do

Answer 15

It is for open a file. It returns an integer value called file descriptor which is just opened.

Question 16

What is PPFDT

Answer 16

Per process file descriptor table. The integer value returned by open() call use as an index in PPFDT

Question 17

What is size of PPFDT

Answer 17

How many files PPFDT that a process can open

Question 18

What are 2 descriptor of a pipe

Answer 18

Write end descriptor

Read end descriptor

Question 19

When a pipe can destroy

Answer 19

• When it could not return 2 descriptors

- Problems in the capacity of bounded buffer