/// <summary>
        /// Submit an expense.
        /// </summary>
        /// <param name="expense">An Expense instance.</param>
        public void SubmitExpense(Expense expense)
        {
            // Submit the expense.
            try
            {
                expense.WorkflowID = Guid.NewGuid();

                ExpenseWorkflowService.SubmitterRequestMessage requestMessage =
                    new ExpenseWorkflowService.SubmitterRequestMessage(expense.WorkflowID, expense);

                ExpenseWorkflowServiceClient proxy = new ExpenseWorkflowServiceClient();
                proxy.SubmitExpense(requestMessage);
                proxy.Close();
            }
            catch (FaultException<ProcessExecutionFault> ex)
            {
                throw new ApplicationException(ex.Message);
            }
        }