The BabDev\ServerPushManager\Contracts\PushManager::link() method is the main method for adding a link with any set of relations and/or attributes which will be converted into an appropriate HTTP/2 Link response header value.

The method accepts three parameters:

• $uri - The URI for the resource
• $rel - The relations for this resource, this may be either a single string or an array of strings to specify multiple relations
• $attributes - An optional array of additional attributes for the resource, these are passed to the Psr\Link\EvolvableLinkInterface::withAttribute() method and the values should follow the specification's requirements

Note that this method returns the $uri passed into it, this allows you to wrap other function calls within calls to the manager (see below for an example).

The BabDev\ServerPushManager\Contracts\PushManager interface defines several helper methods for adding resources to a HTTP/2 Link response header with the appropriate relations, including:

• preload() - Adds the resource with the "preload" relation to the Link header
• dnsPrefetch() - Adds the resource with the "dns-prefetch" relation to the Link header
• preconnect() - Adds the resource with the "preconnect" relation to the Link header
• prefetch() - Adds the resource with the "prefetch" relation to the Link header
• prerender() - Adds the resource with the "prerender" relation to the Link header

Each of these methods accepts two parameters:

• $uri - The URI for the resource
• $attributes - An optional array of additional attributes for the resource, these are passed to the Psr\Link\EvolvableLinkInterface::withAttribute() method and the values should follow the specification's requirements

Note that each of these methods returns the $uri passed into the method, this allows you to wrap other function calls within calls to the manager (see below for an example).

You can specify which assets should have a server push directive directly within your Blade templates by calling the PushManager service. Because the PushManager returns the original URI, you can wrap calls to asset() or mix() with a call to the manager.

<link href="{{ PushManager::preload(mix('css/app.css'), ['as' => 'style']) }}" rel="stylesheet">
<script src="{{ PushManager::preload(asset('js/app.js'), ['as' => 'script']) }}"></script>

You can access the PushManager service by injecting it as a dependency to your class or controller action, through the app() helper using the service ID ('babdev.push_manager') or the class name, or using the facade.

namespace App\Http\Controllers;

use BabDev\ServerPushManager\PushManager;
use Illuminate\Http\Request;

final class HomepageController
{
    private PushManager $pushManager;

    public function __construct(PushManager $pushManager)
    {
        $this->pushManager = $pushManager;
    }

    public function homepageWithConstructor()
    {
        $this->pushManager->preload('https://laravel.com/assets/css/laravel.css', ['as' => 'style']);

        return $this->renderHomepage();
    }

    public function homepageWithMethodInjection(Request $request, PushManager $pushManager)
    {
        $pushManager->preload('https://laravel.com/assets/css/laravel.css', ['as' => 'style']);

        return $this->renderHomepage();
    }

    public function homepageWithAppFunction()
    {
        /** @var PushManager $pushManager */
        $pushManager = app('babdev.push_manager');
        $pushManager->preload('https://laravel.com/assets/css/laravel.css', ['as' => 'style']);

        return $this->renderHomepage();
    }

    public function homepageWithFacade()
    {
        \PushManager::preload('https://laravel.com/assets/css/laravel.css', ['as' => 'style']);

        return $this->renderHomepage();
    }

    private function renderHomepage()
    {
        return view('homepage');
    }
}