what is Terminable Middleware

Answer

Sometimes a middleware may need to do some work after the HTTP response has already been sent to the browser. For example, the "session" middleware included with Laravel writes the session data to storage after the response has been sent to the browser. To accomplish this, you may define the middleware as "terminable".

use Closure;
use Illuminate\Contracts\Routing\TerminableMiddleware;

class StartSession implements TerminableMiddleware {

    public function handle($request, Closure $next)
    {
        return $next($request);
    }

    public function terminate($request, $response)
    {
        // Store the session data...
    }

}

As we can see, in addition to defining a handle method, TerminableMiddleware define a terminate method. This method receives both the request and the response. Once you have defined a terminable middleware, you should add it to the list of global middlewares in your HTTP kernel.