Contract Class in ax 2012

Contract :

[

    DataContractAttribute

,    SysOperationGroupAttribute('Date', "Period", '1')

,SysOperationContractProcessingAttribute(classStr(ICDOCCollectorInformationUIBuilder))

]

public class ICDOCCollectorInformationContract //implements SysOperationValidatable

{

    boolean     ExecuteZero;

    FromDate    fromDate;

    ToDate      toDate;

    Name        dimension;

    AgentCode   agentCode;

    Branch      Branch;

}

[

    DataMemberAttribute('FromDate'),

    //SysOperationLabelAttribute(literalstr("@SYS68117")),

    SysOperationGroupMemberAttribute('Date'),

    //SysOperationGroupMemberAttribute('Bid Submission Date'),

    SysOperationDisplayOrderAttribute('1')

]

public FromDate parmFromDate(FromDate _fromDate = fromDate)

{

    fromDate = _fromDate;

    return fromDate;

}

[

    DataMemberAttribute('ToDate'),

    //SysOperationLabelAttribute(literalstr("@SYS68118")),

    SysOperationGroupMemberAttribute('Date'),

    //SysOperationGroupMemberAttribute('Bid Submission Date'),

    SysOperationDisplayOrderAttribute('2')

]

public ToDate parmToDate(ToDate _toDate = toDate)

{

    toDate = _toDate;

    return toDate;

}

public boolean validate()

{

    boolean isValid = true;

    if(!fromDate)

    {

        isValid = checkFailed("@SYS97591");

    }

    if(!toDate)

    {

        isValid = checkFailed("@SYS97592");

    }

    if(fromDate && toDate)

    {

        if(fromDate > toDate)

        {

            isValid = checkFailed("@SYS120590");

        }

    }

    return isValid;

}

Note: if we extend the class with " implements SysOperationValidatable" then we have to write the validate method compursary