What is message passing in object oriented programming?

Answer 1

Message passing is not limited to object oriented programming, but it is a method by which data is converted to a form that is readable by other "objects" or procedures. Think of it like a program having a mail box that listens for messages from any other program designated as a sender. It sits around waiting for a message, reads that data and acts on it. A message passing architecture is an OS designed to dispatch messages. A message is generally considered an enumerated type (such as an integer) that has semantic meaning to the recepient, ie sending the value 1 to a waiting process could indicate that one process is telling another to shut down or some other arbitrary command. One example of a message is when you click on a button in windows, an application sitting in an event loop (basically a while loop that checks the event received against all available events) waits for that signal to do something (the signal is an integer) and dispatches an appropriate function on reciept such as maximizing or closing a window.

Message passing becomes necessary when you require a method of isolating one process from another's memory and is a simple and lightweight method of allowing multiasking with separate memory areas.

http://en.wikipedia.org/wiki/Message_passing

Answer 2

I would not quite agree with the other answers.

Message passing is based on the idea of a protocole.

The Socket and ServerSocket technology (a technology which use those classes) is used to send message in the text format to another computer. The rule by which a computer codes and decodes those texts sent through Sockets is the protocole . There are a lot of protocoles: HTTP, SMTP.

The fact of sending coded text messages this way (with Sockets) is message passing.

Answer 3

It's as simple as one object passing a message to another object.

Rawlyn.

Answer 4

Parameters in methods.