This is an implementation of a virtual OneD device. The VoneDExecutor class executes code that is provided by the user. The user code defines the class VOneD which consists fo certain function members that need to be supplied.
Devices of this kind are introduced to Online by such an entry in /online_dir/online.xml:
<device> <name>eh_oned01</name> <type>mca</type> <module>mca_8701</module> <device>p99/vonedexecutor/eh.01</device> <control>tango</control> <hostname>haspp99:10000</hostname> </device>