Low Level Function
1.2.2 Debit User's Account

Overview

This Function shall be capable of providing the following facilities:

(1) The ability to debit the Traveller's Electronic Payment account as the result of the recently performed transaction.
(2) If the Traveller's account becomes overdrawn the ability to send a message highlighting this situation to the “Credit Control” function.

Functional Requirements

(a) read the transaction message, and extract the user's ID, account ID, corresponding fee
(b) get the balance of the EP account
(c) debit the balance by the amount of the transaction, and record the operation in the stores of "transactions" Data and "user's account" Data
(d) if the "user's account" is now overdrawn, send an overdraft message to the traveller and to "Credit Control".

Diagrams

The Diagram(s) is (are) the diagram(s) where you can find the function :
  • DFD 1.2 Manage User's Account
  • Functional Tree of Area 1

    • Parent Higher Level Function

    Input logical dataflows

    Output logical dataflows

    User needs

    Number

    Description

    4.1.0.1
    The system shall be able to use a variety of relevant payment methods either electronic or not, including central account and post payment, central account and prepayment, on-board account etc.
    4.1.0.2
    The system shall manage customer data (identification, account, rights of residents, etc.).
    4.1.0.3
    The system shall give exact details of any financial transaction to the traveller.
    4.1.0.5
    The system shall be able to use a variety of payment or receipt means, including contactless "smart cards".
    4.1.2.2
    The system shall enable a single payment to be paid for services offered by different related transport systems (e.g. metro, bus, train, road and parking).
    4.1.3.2
    The system shall make atomic electronic financial transactions, I.e. that are never partially complete whatever the circumstances, even in degraded system modes.
    4.1.3.3
    The system shall have the maximum security necessary for electronic financial transactions.
    4.1.3.4
    The system shall have a low number of incorrect transactions (e.g., non-effective transactions < 1 in 10E-6; erroneous transactions < 1 in 10E-8)
    4.1.3.5
    The system shall provide information in the native language at the output location, and/or from a user selected choice of other appropriate foreign languages.
    4.1.4.1
    The system shall be able to be able to collect evidence on the non-payment of tolls, and other illegal financial transactions.