Joomla HTTP/2 Push Extension

# Introduction

HTTP/2 Push is a feature of the latest HTTP revision that enables the web server to preemptively send resources to the requesting client before the client knows that they are needed. As a result, the number of round-trips that are required to fully load a web page may be reduced, resulting in a potentially large performance boost (especially on slow cellular networks).

# System Requirements

Several system requirements must be met before you can make appropriate use of this plugin:

1. PHP `7.1`+
2. Joomla! `3.8`+
3. HTTP/2 web server with push capability:
1. Apache `2.4.17`+ (with `mod_http2`)
2. NGINX `1.13.9`+

# Installation

[Click here] to download the latest release of the plugin. Once the plugin is downloaded, navigate to 'Extensions' > 'Manage' > 'Install' on your Joomla! site, then click on the 'Upload Package File' tab. Next, drag the downloaded ZIP archive into the upload area to install it.

Tip: For extra security, make sure that the "Verified" tag appears in the left column on the release page. This means that the release was signed and validated using GPG.

# Configuration

Configuration for this plugin can be found on your Joomla! site under 'Extensions' > 'Plugins' by searching for 'HTTP/2 Push' and clicking on the plugin name.

Once you reach the plugin configuration page, hover over the field labels for a detailed description of each.

# Implementation Details

This project is a system plugin for Joomla! that intercepts the [onAfterRender] event. Once the event is triggered, the plugin parses the HTTP response body to find any applicable resources that can be configured for preload or preconnect.

The plugin then sets a [Link] header to inform the web server about the resulting resources. Once the web server is made aware, all (or some) of the resources are pushed to the client.

# Credits

This plugin was originally written by [Clay Freeman] for Bluewall, LLC.

# License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program. If not, see http://www.gnu.org/licenses/.

[Click here]: https://github.com/bluewallweb/plg_http2push/releases/latest
[onAfterRender]: https://docs.joomla.org/Plugin/Events/System#onAfterRender
[Link]: https://www.smashingmagazine.com/2017/04/guide-http2-server-push
[Clay Freeman]: https://github.com/clayfreeman