Application servers #

This page is for engineers who choose how Exponential is served, or who need to know which runtime their code will meet. Since 6.0.15 Exponential ships its own application server, Exponential Velocity, and drives three engines with the same command and settings file. The source of truth is Velocity engines.

Contents #

1. The options
2. Compared
3. What the choice means for code
4. Driving the engines
5. Choosing

The options #

• A web server with PHP-FPM (Apache, nginx and the other servers the README lists). Every request starts PHP from a clean state. Exponential runs behind any web server that can rewrite a URL to index.php.
• Exponential Velocity, engine qbix. A web server written in PHP: the parent loads the application once and forks persistent workers that serve many requests and are reset after each; a response cache can answer repeat public requests before a worker is used. As of 6.0.15 it is required by composer.json (se7enxweb/exponential-velocity), so every installation has it. The project calls it the recommended engine for every stage (Velocity is part of Exponential 6.0.15).
• FrankenPHP, engine frankenphp. Caddy with PHP built in, one binary, downloaded by exp:velocity install and checked against a SHA-256 pin. PHP runs in classic mode (a clean state per request); worker mode is deliberately not offered (FrankenPHP).
• PHP's built-in server, engine php: the shipped default in velocity.ini, because it needs nothing installed. For development only.

Compared #

What the choice means for code #

The same code runs under all of them, and the kernel's rule is that every change must keep working under PHP-FPM, Velocity and FrankenPHP. What the persistent model adds:

• static properties, globals and registrations survive from one request to the next unless they are reset (Concurrency, statics and long-lived processes);
• exit and die end the request, not the worker, through a compatibility layer; kernel code uses eZExecution::cleanExit();
• a worker started before a deploy does not know a new class until it is restarted.

Driving the engines #

php bin/php/console exp:velocity status                          # every engine: role, state, URL
php bin/php/console exp:velocity start                           # the default engine
php bin/php/console exp:velocity graceful                        # reload workers one at a time
php bin/php/console exp:velocity deploy --dry-run --allow-root-user

settings/velocity.ini [ServerSettings] Engine chooses the default engine (php shipped, qbix recommended, frankenphp). The verbs are the same for every engine: start, stop, graceful, restart, kill, status, deploy, command, config, install.

Choosing #

Measure on your own pages before you decide (Performance measurement and benchmarks).

Related pages #

• Velocity persistent workers
• Velocity: running Exponential in a persistent-worker web server
• Deploying with Velocity
• Free documentation: this page is free to copy, translate and improve under the GNU FDL 1.3.