public abstract signal void unit_new(string id, ObjectPath path);
public abstract signal void unit_removed(string id, ObjectPath path);
public abstract signal void job_new(uint32 id, ObjectPath path);
public abstract signal void unit_new(string id, ObjectPath path);
public abstract signal void unit_removed(string id, ObjectPath path);
public abstract signal void job_new(uint32 id, ObjectPath path);