Introduction¶ Add Sqreen to your PHP application to automatically monitor and protect from security issues in production. The Sqreen PHP agent monitors your application against attacks, blocks them, and helps you identify and solve security issues. Architecture¶ The Sqreen agent's architecture has two parts: a daemon and a PHP extension. Sqreen requires both parts to secure your PHP web applications. The PHP extension performs the PHP code instrumentation. It is a compiled extension (like the MySQL or ODBC extensions) using the PHP engine's API. It inspects the PHP internal state to collect signals and apply the configured plugins' actions. The daemon provides a long-running background process. This enables report batch upload, operates plugins and performs asynchronous activities to minimize the performance impact. PHP is designed around transactions, so this architecture is the most efficient one. Once a request is handled, the PHP runtime is destroyed and there is no further chance for the agent to perform any action.