When a resource has a relation to another resource, it should be expressed
as a working link to the resource. By passing the hostname of the server
to the functions, we are able to generate working relation links.
The old polling message system is obsolete now that the worker messages
are implemented. The old system was only used to clean up the persistent
connection pool of a server.
Adds a server-specific parameter, "use_proxy_protocol". If enabled,
a header string is sent to the backend when a routing session connection
changes state to MXS_AUTH_STATE_CONNECTED. The string contains the real
client IP and port.
