As of MySQL 5.5, plugins have access to server “services.” The services interface exposes server functionality that plugins can call. It complements the plugin API and has these characteristics:
Services enable plugins to access code inside the server using ordinary function calls. Services are also available to user-defined functions (UDFs).
Services are portable and work on multiple platforms.
The interface includes a versioning mechanism so that plugin versions can be checked at load time against service versions supported by the server. Versioning protects against incompatibilities between the version of a service that the server provides and the version of the service expected or required by a plugin.
For information about plugins for testing plugin services, see https://dev.mysql.com/doc/dev/mysql-server/latest/PAGE_PLUGINS.html, in https://dev.mysql.com/doc/dev/mysql-server/latest/PAGE_MYSQL_TEST_RUN.html.