MySQL Server includes a component-based infrastructure for extending server capabilities. A component provides services that are available to the server and other components. (With respect to service use, the server is a component, equal to other components.) Components interact with each other only through the services they provide.
MySQL distributions include several components that implement server extensions:
A component for checking passwords. See Section 6.4.3, “The Password Validation Component”.
A component that enables applications to add their own message events to the audit log. See Section 6.4.6, “The Audit Message Component”.
A component that implements a user-defined function for accessing query attributes. See Section 9.6, “Query Attributes”.
System and status variables implemented by a component are exposed
when the component is installed and have names that begin with a
component-specific prefix. For example, the
log_filter_dragnet error log filter component
implements a system variable named
log_error_filter_rules, the full name of which is
refer to this variable, use the full name.
The following sections describe how to install and uninstall components, and how to determine at runtime which components are installed and obtain information about them.
For information about the internal implementation of components, see the MySQL Server Doxygen documentation, available at https://dev.mysql.com/doc/index-other.html. For example, if you intend to write your own components, this information is important for understanding how components work.