A caching strategy is one of the most important items for discussion when it comes to web applications; with microservices it is no different.

When we speak of cache at the client level, it means that the request only passes to be processed on the backend, if really necessary. In other words, it tries to block direct access to the backend to requests that have already been implemented in the recent past.

A very useful tool for this strategy is the Varnish Cache, defined as: the Varnish Cache accelerator is a web application also known as reverse HTTP proxy caching. In the following diagram, we can see the operation of Varnish Cache:

The requests come from various types of web clients. Varnish Cache passes the request to the Server the first time only and stores the received data from the Server. If a second request for the same information already in the Varnish Cache is made, then Varnish Cache will answer the request, leaving the Server free of such access.

The Varnish Cache can store a number of different types of information in memory, but it is critical and targets the transmitted data. If the information is not componentized, Varnish always let the request go to the Server; you will have no way of knowing if the request is the same type.