tailieunhanh - Programming the Be Operating System-Chapter 9: Messages and Threads

Tham khảo tài liệu 'programming the be operating system-chapter 9: messages and threads', công nghệ thông tin, hệ điều hành phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 9 In this chapter The Application Kit and Messages Application-Defined Messages Messages and Threads Several years ago Be Inc. set out to develop a new operating system one they eventually dubbed the Media OS. The goal was to create an operating system that could keep up with the computationally intensive demands of media professionals who routinely worked with complex and resource-hungry graphics and audio files. From the start Be knew that threads and messages would be of paramount importance. A multithreaded environment means that a single application can simultaneously carry out multiple tasks. On a single-processor machine CPU idle time is reduced as the processor services one thread followed by another. On a multiprocessor machine task time really improves as different CPUs can be dedicated to the servicing of different threads. Threads can be considered roadways that allow the system to communicate with an object one object to communicate with another object and even one application to communicate with another application. Continuing with the analogy messages are the vehicles that carry the information or data that is to be passed from one entity to another. Chapter 4 Windows Views and Messages introduced messages and seldom since then have a couple of pages passed without a direct or indirect reference to messages. In this chapter I ll formally explain of how messages and threads work. In doing so you ll see how your application can create its own messages and use them to let one object tell another object what to do. You ll see how sending a message can trigger an object to perform some desired action. You ll also see how a message can be filled with any manner of data before it s sent. Once received the recipient object has access to any and all of the data held within the message. 322 The Application Kit and Messages 323 The Application Kit and Messages Servers are background processes that exist to serve the basic low-level needs of applications. The .