Getting started
In this section, readers will get an overview of asynchronous applications. The requirements, design, and implementation details will be discussed in brief.
Synchronous applications
Synchronous applications are programs that can process events, requests, and tasks sequentially with an order, and where one needs to finish in order for another to begin:

As shown in the preceding diagram, an asynchronous application will process one request after another, meaning any requests coming simultaneously will be forced to wait until the initially received request has finished processing. These sort of applications have their pros and cons, for example, in GUI frameworks such as Java Swing.
Asynchronous applications
Asynchronous applications are programs that can process events, requests, and tasks with time slicing so that one request can be active and run while another one is also but not running:

Modern web servers, As shown in the preceding diagram, an asynchronous application can accept...