--- /dev/null
+# Stack/Builder
+
+Builder for stack middlewares based on HttpKernelInterface.
+
+Stack/Builder is a small library that helps you construct a nested
+HttpKernelInterface decorator tree. It models it as a stack of middlewares.
+
+## Example
+
+If you want to decorate a [silex](https://github.com/fabpot/Silex) app with
+session and cache middlewares, you'll have to do something like this:
+
+```php
+use Symfony\Component\HttpKernel\HttpCache\Store;
+
+$app = new Silex\Application();
+
+$app->get('/', function () {
+ return 'Hello World!';
+});
+
+$app = new Stack\Session(
+ new Symfony\Component\HttpKernel\HttpCache\HttpCache(
+ $app,
+ new Store(__DIR__.'/cache')
+ )
+);
+```
+
+This can get quite annoying indeed. Stack/Builder simplifies that:
+
+```php
+$stack = (new Stack\Builder())
+ ->push('Stack\Session')
+ ->push('Symfony\Component\HttpKernel\HttpCache\HttpCache', new Store(__DIR__.'/cache'));
+
+$app = $stack->resolve($app);
+```
+As you can see, by arranging the layers as a stack, they become a lot easier
+to work with.
+
+In the front controller, you need to serve the request:
+
+```php
+use Symfony\Component\HttpFoundation\Request;
+
+$request = Request::createFromGlobals();
+$response = $app->handle($request)->send();
+$app->terminate($request, $response);
+```
+Stack/Builder also supports pushing a `callable` on to the stack, for situations
+where instantiating middlewares might be more complicated. The `callable` should
+accept a `HttpKernelInterface` as the first argument and should also return a
+`HttpKernelInterface`. The example above could be rewritten as:
+
+```php
+$stack = (new Stack\Builder())
+ ->push('Stack\Session')
+ ->push(function ($app) {
+ $cache = new HttpCache($app, new Store(__DIR__.'/cache'));
+ return $cache;
+ })
+;
+```
+
+## Inspiration
+
+* [Rack::Builder](http://rack.rubyforge.org/doc/Rack/Builder.html)
+* [HttpKernel middlewares](https://igor.io/2013/02/02/http-kernel-middlewares.html)