Implementing the Pub/Sub design pattern
The Publish/Subscribe (Pub/Sub) design pattern often forms the basis of software event-driven programming. This methodology allows asynchronous communications between different software applications, or different software modules within a single application. The purpose of the pattern is to allow a method or function to publish a signal when an action of significance has taken place. One or more classes would then subscribe and take action if a certain signal has been published.
Example of such actions are when the database is modified, or when a user has logged in. Another common use for this design pattern is when an application delivers news feeds. If an urgent news item has been posted, the application would publish this fact, allowing client subscribers to refresh their news listings.
How to do it...
- First, we define our publisher class,
Application\PubSub\Publisher. You'll notice that we are making use of two useful Standard PHP Library (SPL...
