In this chapter, we will first learn how to implement full-text search using Whoosh and Elasticsearch. Full-text search becomes important for a web application that offers a lot of content and options, such as an e-commerce site. Next, we will catch up on signals that help decouple applications by sending notifications (signals) when an action is performed somewhere in the application. This action is caught by a subscriber/receiver, which can perform an action accordingly. This is followed by implementing caching for our Flask application.

We will also see how e-mail support is added to our application and how e-mails can be sent directly from the application on different actions. We will then see how we can make our application asynchronous. By default, WSGI applications are synchronous and blocking, that is, by default, they do not serve multiple simultaneous requests together. We will see how to deal with this via a small example. We will also integrate Celery with our application...