Getting server instance of client-side EntityPlayer

[Rheel]

Hello everyone! I was wondering if it is possible to get the serverside instance of a client-side EntityPlayer. If so, how would I need to do it? I was thinking

 

FMLCommonHandler.instance().getMinecraftServerInstance().getServer().worldServerForDimension(entity.worldObj.provider.dimensionId)

 

getting the serverside world like this, but the .getMinecraftServerInstance() is null. Is there any way that would work?

[Rheel]

Getting and saving serverside information with a GUI.