Class responsible for converting between an object and its id.
This, the default implementation, uses an object’s local ObjectSpace id as its id. This means that an object’s identification over drb remains valid only while that object instance remains alive within the server runtime.
For alternative mechanisms, see DRb::TimerIdConv in rdb/timeridconv.rb and DRbNameIdConv in sample/name.rb in the full drb distribution.