Operating Systems Chapter on Communication Links

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Questions and Answers

What is the main purpose of message passing in process communication?

To establish a direct link between network devices

To synchronize actions when accessing shared memory

To communicate without using shared variables (correct)

To manage memory allocation between processes

Which of the following operations is NOT part of the IPC facility?

link(process)

send(message)

receive(message)

synchronize(action) (correct)

What can be a characteristic of the communication link established between processes P and Q?

It can only be unidirectional.

It can be associated with more than two processes.

It can accommodate messages of variable size. (correct)

It must have a fixed capacity.

Which scenario describes indirect communication in message passing?

Messages are sent and received using a shared mailbox. Signup and view all the answers

What is a potential issue in establishing communication links between processes?

Determining if a link can be bi-directional or unidirectional. Signup and view all the answers

Which synchronization mechanism is primarily associated with accessing shared memory?

Locking mechanisms Signup and view all the answers

What is the key characteristic of ordinary pipes in process communication?

They require a parent-child relationship. Signup and view all the answers

What is a feature of named pipes compared to ordinary pipes?

They can be accessed without a parent-child relationship. Signup and view all the answers

In a remote procedure call (RPC), what role does the client-side stub play?

It locates the server and marshals parameters. Signup and view all the answers

Which of the following best describes the nature of communication provided by ordinary pipes?

Unidirectional communication. Signup and view all the answers

What does the server-side stub do in a remote procedure call setup?

It unpacks the marshalled parameters and performs the procedure. Signup and view all the answers

What is true regarding the pipes in terms of communication directionality?

Named pipes allow for bidirectional communication by default. Signup and view all the answers

Which property differentiates remote procedure calls from traditional procedure calls?

They can operate across networked systems. Signup and view all the answers

What is the term used for the parent process creating a pipe to communicate with its child process?

Producer-consumer model. Signup and view all the answers

What must processes do in direct communication to send a message to another process?

Name each other explicitly Signup and view all the answers

Which statement about indirect communication is true?

Processes can communicate only if they share a mailbox Signup and view all the answers

Which of the following correctly describes mailbox sharing?

Several processes can receive messages from a shared mailbox Signup and view all the answers

What is a characteristic of a link in direct communication?

Is associated with exactly one pair of communicating processes Signup and view all the answers

What operation is NOT defined for mailboxes in indirect communication?

Establish a direct link between two processes Signup and view all the answers

In which scenario do many processes share a single communication link?

In indirect communication, through a mailbox Signup and view all the answers

Which statement best describes the communication method of sending messages to a mailbox?

Messages are directed and received from mailboxes identified by unique IDs Signup and view all the answers

What must be true for a link to be established in indirect communication?

Processes must share a common mailbox Signup and view all the answers

Study Notes

Implementation of Communication Link

Communication links can be categorized into physical types, such as shared memory, hardware bus, and network.
Logical communication links include direct or indirect communication modes, and can be synchronous or asynchronous, with buffering being automatic or explicit.

Direct Communication

In direct communication, processes must explicitly name each other to exchange messages with commands like send(P, message) and receive(Q, message).
Links are automatically established and are uniquely associated with one pair of communicating processes.
Each communication pair has exactly one communication link, which can be unidirectional or, more commonly, bi-directional.

Indirect Communication

Messages are sent and received through mailboxes (ports) that have unique identifiers.
Processes can only communicate if they share a mailbox, establishing the link necessary for communication.
Links can connect multiple processes and may be unidirectional or bi-directional, allowing each pair of processes to share several links.

Operations of Indirect Communication

Functions include creating a new mailbox, sending and receiving messages through that mailbox, and deleting a mailbox.
Key command primitives are send(A, message) for sending messages and receive(A, message) for receiving messages.

Multiple processes (e.g., P1, P2, P3) can share a mailbox (A) for communication, where P1 sends, and P2 and P3 receive the messages.
Mailbox sharing can lead to scenarios where multiple recipients may receive the same message, allowing for unbounded capacity without the sender waiting.

Pipes

Pipes facilitate communication between processes; they can be unidirectional or bi-directional.
Considerations include the relationship between communicating processes and whether pipes can be accessed across a network.
Ordinary pipes require a parent-child relationship for communication, whereas named pipes do not impose such a constraint.

Ordinary Pipes

Ordinary pipes function in a producer-consumer model, where the producer writes, and the consumer reads from opposite ends of the pipe.
These pipes are unidirectional, requiring the parent-child relationship for communication, often referred to as anonymous pipes in Windows.

Remote Procedure Calls (RPC)

RPC simplifies procedure calls between processes on network systems using ports to differentiate services.
Client-side stubs act as proxies for server procedures, marshaling parameters for transmission.
The server-side stub unpacks these parameters to complete the procedure execution on the server.

Inter-Process Communication (IPC) - Message Passing

IPC allows process communication without shared variables by using operations such as send(message) and receive(message).
The message size in IPC can be fixed or variable, providing flexible communication between processes.

Message Passing Key Points

To facilitate communication, processes need to establish a communication link and exchange messages using send/receive operations.
Essential implementation issues involve link establishment, link capacity, message size handling, and whether links are unidirectional or bi-directional.

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Description

This quiz covers the implementation of communication links as presented in the 10th edition of Operating System Concepts by Silberschatz, Galvin, and Gagne. It focuses on both physical and logical aspects including shared memory, network considerations, and synchronization methods. Test your understanding of key concepts related to communication mechanisms in operating systems.