SSRS : Contract Class & Debug it (parameter)

Hi,
Below is the sample code to Develop the contract class.
Here I need to pass the “Date” as the parameter, based on the selected data I need to get the data.

1) [DataContractAttribute]
class SrsRDPContractIndemnity
{
StartDate        tillDate;
}

2)  [DataMemberAttribute(“Date”)]
public StartDate asOfDate(StartDate _tilldate = today())
{
tillDate = _tilldate;
return tillDate;
}

Debug the contact class: 
static void SSRS_ContractclsDEBUG(Args _args)
{
ProdRouteTrans  prodRouteTrans;
//ACWAPIPETotalItemProdPerMonthTmp  acwaPIPETotalItemProdPerMonthTmp;
MZK_PayrollIndemnityTmp payrollIndemnityTmp;
IndemnityRDP dataprovider = new IndemnityRDP();
SrsRDPContractIndemnity    contract    = new SrsRDPContractIndemnity();
;
contract.asOfDate(today());
dataProvider.parmDataContract(contract);
dataProvider.processReport();
payrollIndemnityTmp = dataProvider.getDate();
}