you propbably already know this, but FWIW, you can do server-side sorting in gridModel.providerModel.restParams for some BO Methods such as GetRows and GetList (I believe) like so:
{
"whereClauseABCCode": "By ABCCode DESC"
}
call:
/Erp.BO.ABCCodeSvc/GetRows?whereClauseABCCode=By+ABCCode+DESC&pageSize=80&absolutePage=1
oddly it’s in a where clause so there’s some legacy parsing going on some where. 
