Simple custom service implementation example ax 2012

class VKOCalcService
{
}
[SysEntryPointAttribute(true),
 AifCollectionTypeAttribute('return', Types::Class, classStr(VKOCalcContract)),
 AifCollectionTypeAttribute('_calcContract', Types::Class, classStr(VKOCalcResponseContract))]
public VKOCalcResponseContract calc(VKOCalcContract _calcContract)
{
    VKOCalcResponseContract response    = new VKOCalcResponseContract();
    real                    result;
    int                     a1          = _calcContract.parmArg1(),
                            a2          = _calcContract.parmArg2();

    switch (_calcContract.parmOperation())
    {
        case VKOCalcOperation::add:
            result = a1 + a2;
            break;
        case VKOCalcOperation::sub:
            result = a1 - a2;
            break;
        case VKOCalcOperation::multiply:
            result = a1 * a2;
            break;
        case VKOCalcOperation::divide:
            result = a1 / a2;
            break;
    }

    response.parmResult(result);

    return response;
}

[DataContractAttribute("Calc")]
class VKOCalcContract
{
    int                 arg1;
    int                 arg2;
    VKOCalcOperation    operation;
    VKOCalcSubContract  subCalc;
    List                subList;
}
[DataMemberAttribute("arg1")]
public int parmArg1(int _arg1 = arg1)
{
    arg1 = _arg1;
    return arg1;
}
[DataMemberAttribute("arg2")]
public int parmArg2(int _arg2 = arg2)
{
    arg2 = _arg2;
    return arg2;
}
[DataMemberAttribute("operation")]
public int parmOperation(int _operation = operation)
{
    operation = _operation;
    return operation;
}
//This parm is just for demonstration on how you can use nested contracts and lists
[DataMemberAttribute("subCalc")]
public VKOCalcSubContract parmSubCalc(VKOCalcSubContract _subCalc = subCalc)
{
    subCalc = _subCalc;
    return subCalc;
}

[DataContractAttribute("SubCalc")]
class VKOCalcSubContract
{
    int a;
}
[DataMemberAttribute("a")]
public int parmA(int _a = a)
{
    a = _a;
    return a;
}

[DataContractAttribute]
class VKOCalcResponseContract
{
    real result;
}
[DataMemberAttribute("result")]
public real parmResult(real _result = result)
{
    result = _result;
    return result;
}

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:dat="http://schemas.microsoft.com/dynamics/2010/01/datacontracts" xmlns:arr="http://schemas.microsoft.com/2003/10/Serialization/Arrays" xmlns:tem="http://tempuri.org" xmlns:dyn="http://schemas.datacontract.org/2004/07/Dynamics.Ax.Application">
   <soapenv:Header>
   </soapenv:Header>
   <soapenv:Body>
      <tem:VKOCalcServiceCalcRequest>
         <!--Optional:-->
         <tem:_calcContract>
            <!--Optional:-->
            <dyn:arg1>3</dyn:arg1>
            <!--Optional:-->
            <dyn:arg2>4</dyn:arg2>
            <!--Optional:-->
            <dyn:operation>0</dyn:operation>
         </tem:_calcContract>
      </tem:VKOCalcServiceCalcRequest>
   </soapenv:Body>
</soapenv:Envelope>

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
   <s:Body>
      <VKOCalcServiceCalcResponse xmlns="http://tempuri.org">
         <response xmlns:b="http://schemas.datacontract.org/2004/07/Dynamics.Ax.Application" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
            <b:result>7</b:result>
         </response>
      </VKOCalcServiceCalcResponse>
   </s:Body>
</s:Envelope>