Hi,
I am a bit confused and mixing the concepts that "In Indirect Communication, two processes can only communicate if they mail box." Sharing a mail box is like sharing memory. I am bit confused that the main theme of IPC is to avoid sharing memory for process communication. But here the technique is based on sharing the mail box.
Thanks.
 So, do not worry dear its so easy question and its my wish to help you.
No, we can not say that basic goal of IPC is to avoid sharing. Its main goal is to provide the facility of communication between the processes. And there are ways to achieve IPC which includes both direct as well as indirect communication. Mail box are different in a way that the sender do not specify the address of the receiver. The receiving process itself have to contact the mailbox to get its message. So this is basically a way of indirect communication.
The answer of the other part of your question is that the Sibling process with respect to pipe system call means that the related processes can communicate through pipe system call. One is parent child relationship and the other is brother-brother (sibling) relationship. For example a parent has created two children A and B. Then these children A and B are siblings and hence can communicate through pipe system call.
Take care.
What's up John, here is your solution, the statement 'in indirect communication two processes can communicate if they mailbox is true. But sharing a mail box and sharing memory are two different things in that sharing memory involves direct communication since the information goes directly to the memory whereas sharing a mailbox is indirect communication. In sharing a memory, the following processes are involved; Synchronous-
This is the process where both the sender and receiver receive blocking operations. It is also known as rendezvous Asynchronous- its where the sending operation does not block the receiver, but the receiving operation blocks the sender. In mail box, its the instance of a pipe, where two objects cannot enter at the same time,the mails/messages being sent cannot allow the messages coming in to operate, the first messages to come in are the first to get out. The other messages have to wait for the process to complete in order to be sent. Multiple messages can be stored, but not exceeding the mailbox size. The Inter Process Communication tries to use this method since it is much more effective by communicating much more flexible than the sharing of messages.
Thanks
obA
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