Event-Driven Structures
Request-response is not the only software architecture that can be used in a system. There can also be requests that don't require an immediate response. Perhaps there's no interest in a response, as the task can be done without the caller being required to wait, or perhaps it takes a long time and the caller doesn't want to be waiting for it. In any case, there's the option to, from the point of view of the caller, just send a message and proceed.
This message is called an event, and there are multiple uses for this kind of system. In this chapter, we will introduce the concept, and we will describe in detail one of the most popular uses of it: creating asynchronous tasks that are executed in the background while the caller of the task continues uninterrupted.
In the chapter, we will describe the basics of asynchronous tasks, including the details of queueing systems and how to generate automatically scheduled tasks.
We will...