Feature

Drupal 8 represents a radical shift, both technically and culturally, from previous versions. Perusing through the Drupal 8 code base, many parts may be unfamiliar. One bit in particular, though, is especially unusual: A new directory named /core/vendor. What is this mysterious place, and who is vending?

The "vendor" directory represents Drupal's largest cultural shift. It is where Drupal's 3rd party dependencies are stored. The structure of that directory is a product of Composer, the PHP-standard mechanism for declaring dependencies on other packages and downloading them as needed. We won't go into detail about how Composer works; for that, see my article in the September 2013 issue of Drupal Watchdog, Composer: Sharing Wider.

But what 3rd party code are we actually using, and why?

Crack open your IDE if you want, or just follow along at home, as we embark on a tour of Drupal 8's 3rd party dependencies. (We won't be going in alphabetical order.)

Guzzle

Perhaps the easiest to discuss is Guzzle. Guzzle is an HTTP client for PHP; that is, it allows you to make outbound HTTP requests with far more flexibility (and a far, far nicer API) than using curl or some other very low-level library.

Drupal had its own HTTP client for a long time... sort of. The drupal_http_request() function has been around longer than I have, and served as Drupal's sole outbound HTTP utility. Unfortunately, it was never very good. In fact, it sucked. HTTP is not a simple spec, especially HTTP 1.1, and supporting it properly is difficult. drupal_http_request() was always an after-thought, and lacked many features that some users needed.