Report on Object Modeling of ATM System: Transaction Subsystem Design

This report provides a comprehensive analysis of the object modeling of an ATM system, with a specific focus on the transaction subsystem. It begins by introducing sequence diagrams as a method for modeling complex systems and then decomposes the ATM system into various subsystems, highlighting the transaction module which involves activities like cash withdrawal, cash deposit, and amount transfer. The report details the system's components, including the card reader, keypad, printer, cash dispenser, and screen, and explains the system's operations, such as authentication, ATM withdrawal, depositing funds, and money transfer. It also covers data communication between the ATM and the backend processing system, session handling, and feedback mechanisms. Furthermore, the report touches upon the database and the backend processing system, concluding with a summary, conclusion, and recommendations related to the ATM system's object modeling and transaction processes. Desklib offers a wide range of solved assignments and past papers for students.

Running head: OBJECT MODELING 1
ATM System Modelling
Author Name(s), First M. Last, Omit Titles and Degrees
Institutional Affiliation(s)
Author Note
Include any grant/funding information and a complete correspondence address.

OBJECT MODELLING 2
Contents
System Modelling................................................................................................................5
Sequence diagram for the transaction subsystem of the ATM........................................5
System Documentation........................................................................................................9
System Transactions............................................................................................................9
Cash Withdrawal.............................................................................................................9
Cash Deposit....................................................................................................................9
Amount Transfer..............................................................................................................9
System Components............................................................................................................9
The card Reader...............................................................................................................9
The Keypad....................................................................................................................10
The Printer.....................................................................................................................10
The screen......................................................................................................................11
System Operations.............................................................................................................11
Authentication................................................................................................................11
ATM Withdrawal...........................................................................................................12
Depositing Funds...........................................................................................................12
Transfer Money.............................................................................................................13
Data communication..........................................................................................................13
Session handling................................................................................................................14

OBJECT MODELLING 3
Feedback mechanism.........................................................................................................14
The database......................................................................................................................14
The backend processing system.........................................................................................15
Summary............................................................................................................................15
Conclusion.........................................................................................................................15
Recommendations..............................................................................................................15

OBJECT MODELLING 4
Table of figures
Figure 1............................................................................................................................................5
Figure 2. Withdrawal Transaction...................................................................................................6
Figure 3. Deposit Transaction..........................................................................................................7
Figure 4. Money Transfer................................................................................................................8

OBJECT MODELLING 5
System Modelling
Sequence diagram for the transaction subsystem of the ATM
Sequnce diagrams allow engineers to model complex systems that interate functionality
that may be difficult to understand without proper visual representation (Campean & Yildirim,
2017). Thus by use of sequnce diagrams we can be able to show how a certain processing task is
carried out through sending messages between the interacting entities(Refsdal, Husa, & Stølen,
2005). From the use cases defined in the system design, we can be able to decompose the ATM
system into various subsystems. One major sub-system we can derive is the transaction module.
This part is composed of activities that involve the moving cash from one’s account to another or
from the account to physical cash and vice versa. The use case diagram is shown below.
Figure 1. Collins ATM Transaction Subsystem Use Cases
Withraw Cash
Withraw Cash
Withraw Cash

OBJECT MODELLING 6
Figure 2. Withdrawal Transaction

OBJECT MODELLING 7
Figure 3. Deposit Transaction

OBJECT MODELLING 8
Figure 4. Money Transfer

OBJECT MODELLING 9
System Documentation
The ATM system acts as the interface between the customers and the bank. It totally
eliminates the need for customers to visit the bank for basic transactions that can be self-served
(Saleh, 2016).
System Transactions
Our case study is modeled after the ATM to perform the following truncations:
Cash Withdrawal
Cash withdrawal transactions involve the transfer of money from the user’s account to
hard cash. During this process, the account is debited and the user is handed the money through
the cash dispenser.
Cash Deposit
Under this transaction, the user is able to add money to his/her account or even to
someone else’s account.
Amount Transfer
These services are offered by the ATM system and therefore, they are very important to
discuss. This is because they are at the heart of operation of any bank. They function by giving
direct service to the client thus adding a lot of value to the service model of any bank.
System Components
The transaction subsystem is made up of both hardware and software. The hardware
components involved in the operation of the ATM Transaction subsystem are:
The card Reader
This is the first component that the user interacts with on reaching the ATM. The card
reader is mostly located on the right of the system. It has an indicator light to be guide the user

OBJECT MODELLING 10
on how to insert the card. The Card reader reads the details and sends them to the transaction
processing system within the bank. In this design, the card reader acts in a similar fashion. From
the withdrawal sequence diagram (figure 2) above, the card initiates the transaction process.
Once the user enters the card, it triggers the ATM to request for password. This is the beginning
of the transaction. The card must be well inserted or the card reader will not be able read the
account information.
The Keypad
This part of the ATM is used for entering user input into the system. It may be a physical
keypad or a virtual keypad that appears on the screen. This keypad is very basic with only
numeric values and some special keys such as delete and send. This is because the ATM does not
handle very complex information from the user. In most cases, user input includes only selection
or entering numeric data such as amount or account number.
The Printer
The printer is used to produce hardcopy document containing information about the
transaction that has been carried out. The output from this device depends on whether the user
has instructed the ATM to produce the receipt or the document. The printer used is the thermal
printer. The output from the printer is very basic.
Cash dispenser
The cash dispenser is used to transfer the physical or hard cash from the bank to the
client. When this happens, the client’s account is debited and a similar amount of money is
released by the cash dispenser.

OBJECT MODELLING 11
The screen
This is the main output device for the ATM. Any instructions will be displayed on this
device. It also acts as the input device for the system that implement the virtual keypad.
System Operations
Authentication
Authentication is very important to ensure that the person who is carrying out the
transaction is the owner of the card (Mondal, Deb, & Adnan, 2017)
When the user inserts the card into the card reader, he/she is prompted for a password. In
order to be able to enter this information, the user interacts with the second hardware component,
the keypad. Although there has been newer systems that have done away with the keypad, many
system still utilize this hardware component. When the user types the password, the information
is read by the ATM main processing unit. This information is then sent to the backend
processing for validation. This is achieved through the transmission of data over the network. In
the case of withdrawal shown in figure 2, this is achieved via the “sendVerifyMsg” function that
takes the pin as the input. Once this information is received by the backend processing system,
the pin is checked against the one stored on the database.
A proceed message is sent back to the ATM if the PIN is found to be correct. This allows
the transaction to proceed as required. The ATM then displays the use a list of options to select
the type of transaction. Here, in our model ATM system, this can either be withdrawing of cash,
change of PIN, depositing money, updating passbook or checking of balance. The user selects
the option in order to proceed. In case of invalid request, the session will be terminated and the
user required to enter the password again.

OBJECT MODELLING 12
ATM Withdrawal
When the user selects the correct option, say for example withdrawal of funds, the ATM
will prompt the user to enter the amount to withdraw. When the user responds with the amount,
the system will send a request to the backend database to check whether the user has sufficient
funds. If the funds are available, the system will send a message to the cash dispenser to dispense
the cash. Before this can happen, the ATM will prompt the user whether he/she would like to do
another transaction. If the answer is no, the ATM will release the card and dispense the cash
from the cash dispenser. In case of a response to the contrary, the ATM will dispense the cash
and still hold the card waiting for another instruction. If no transaction is given the ATM will
release the card and print the receipt and the session will be closed.
Depositing Funds
In this model system, the transaction would have taken a different route if the user had
selected deposit of funds instead of withdrawal. The ATM would have prompted the user to enter
the account to deposit to. After receiving the input of the account number, the ATM will then
send the number to the backend processing system to validate the existence of the account. This
process is carried out in order to reduce the chances of clients depositing money into inexistent
or flagged accounts to prevent fraud (Ibrahim, Mishra, & Barroon, 2010). When the account is
found, the system prompts the user to enter the amount that he/she wants to deposit. After the
user types the amount, the ATM will wait for the envelope containing the money to be deposited
in the ATM deposit box. Here the ATM will verify the amount that has been deposited to ensure
that it is the same as the user has typed into the system. When the amount match the user input,
the system will send a message to the backend processing system to credit the account. Once the
process is complete, the ATM will print the deposit slip to the user as a proof of payment.