There are a lot of useful information that can be collected during the generation of a Response from Drupal. For example:

• How many queries were executed?
• Which route has matched?
• Which events were generated?
• How many (and which) forms, or blocks, or views were made?
• ...

Thanks to the set of services on which is based the core of Drupal 8, retrieve all this data in a simple way is finally possible. Almost all in Drupal 8 is managed by a service and the Symfony Service Container allows us to easily replace these services with their "traceable" version.

In this session we will see:

• How this technique has been exploited to realize the Webprofiler module.
• How to alters or how to replace core (and contrib) services.
• How the Service Container's compiler mechanism works.
• How to add a new Data Collector to extract and store specific information by a contrib module.