Laravel: Up & Running, 2nd Edition

Chapter 16. Queues, Jobs, Events, Broadcasting, and the Scheduler

So far we’ve covered some of the most common structures that power web applications: databases, mail, filesystems, and more. All of these are common across a majority of applications and frameworks.

Laravel also provides facilities for some less common architecture patterns and application structures. In this chapter we’ll cover Laravel’s tools for implementing queues, queued jobs, events, and WebSocket event publishing. We’ll also cover Laravel’s scheduler, which makes manually edited cron schedules a thing of the past.

Queues

To understand what a queue is, just think about the idea of “queueing up” in a line at the bank. Even if there are multiple lines—queues—only one person is being served at a time from each queue, and each person will eventually reach the front and be served. In some banks, it’s a strict first-in-first-out sort of policy, but in other banks, there’s not an exact guarantee that someone won’t cut ahead of you in line at some point. Essentially, someone can get added to the queue, be removed from the queue prematurely, or be successfully “processed” and then removed. Someone might even hit the front of the queue, not be able to be served correctly, return to the queue for a time, and then be processed again.

Queues in programming are very similar. Your application adds a “job” to a queue, which is a chunk of code that tells the application how to perform a particular behavior. Then some other ...