University On-Pay Mobile App Design and Implementation Project

This assignment presents the design and development of the On-Pay mobile application, a system for facilitating online money transactions. The application is designed for Android users and features a three-tier system comprising presentation, logic, and data tiers. The project includes detailed descriptions of the application's functionality, including user interfaces, and diagrams such as class, activity, sequence, and use-case diagrams. The design emphasizes robustness, fault tolerance, minimal recovery time, scalability, and security. The application allows users to transfer money using their mobile numbers or QR codes, directly linking to their bank accounts. The design ensures the application's stability and security, with fault tolerance mechanisms to handle network or transaction issues, and minimal recovery time. The system is designed to be scalable, allowing for future user growth and is designed to be secure, protecting user financial data. The document concludes with a list of relevant references.

Running head: ON PAY
System Development:
On-Pay
Name of the Student:
Name of the University:
Author Note

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Table of Contents
Description of the application..........................................................................................................2
Tiers of the system...........................................................................................................................2
Overall structure of implementation................................................................................................2
Class diagram...................................................................................................................................3
Activity diagram..............................................................................................................................4
Sequence diagram............................................................................................................................5
Use-case diagram.............................................................................................................................6
User interfaces design......................................................................................................................6
Demonstrate if the design is robust.................................................................................................8
Fault tolerant....................................................................................................................................8
Minimal recovery time....................................................................................................................9
Scalable............................................................................................................................................9
Secure..............................................................................................................................................9
References......................................................................................................................................10

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Description of the application
The design of the application is made for online money transactions among different
users. The application would help the users in transferring money online so that there would be
no requirement of physical cash among the users. The name of the application is On-Pay. On-
Pay is an application that allows the users to get connected to their near and dear ones and make
money transaction on the go [2]. The system does not require the user to hold a wallet. Rather the
users can directly send money from their bank to the other users. This application is currently
being designed for android users and later on the iOS version of the application would be
released later.
Tiers of the system
The application would be maintaining a three tier system. The three main tiers of the
application would be:
Presentation Tier: This is the tier which would consist of the user interface and the navigation
functionalities of the users are to be implemented in this tier of the system.
Logic Tier: The logical tier is composed of the back end coding for the design of the system. The
connection to the bank and the storage of the bank details are in this tier.
Data Tier: This tier is the last layer in the application. This layer consists of the database and the
server information.
Overall structure of implementation
The application design would provide a platform for the smart phone users to transfer
money among themselves very easily [1]. For the transaction process the user has to log in to the
application using the mobile number of the user and the mobile number of the user would be the
identification number of the user. This would help the other users to get connected to the other
and perform the required transactions with them. The user is also required to connect themselves
to the bank. The application also allows the users to get connected to other users by scanning the
QR code of the other users.

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Class diagram

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Activity diagram

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Sequence diagram

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Use-case diagram
User interfaces design
Homepage

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User Interactions and Transactions
Demonstrate if the design is robust
The robustness in the context of a transaction system design can be referred to the
stability, resistance and the security in the system. The design of the system is made according to
the requirement of the service provider for the application. It is very easy to understand for the
smart phone user. They would be already accustomed to this type of designs and hence there
would be no difficulty in understanding the procedures that are to be performed in the system.
Fault tolerant
The application is fault tolerant. In case of a transaction fault due the network connection
or some other issues the system would be changing its position back to it’s normal position and

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there would be no change in the database of the system [2]. The account details of the user would
remain the same according to the details it was provided earlier. The user account would be
restored back to its previous state.
Minimal recovery time
The recovery time of the system is also very minimal. The system would be acting like an
ATM system which is online and hence the time required for the recovery of the system is very
minimal [4]. However the user has to get connected to the bank by using the application and
hence the servers of the bank might be down and hence the recovery time for the transaction
process would depend the bank server and the network the application is run on. However all the
client side procedures of the application would be responding to the user in a very minimal
recovery time.
Scalable
The system that is constructed is scalable in nature as the programming of the system is
done by keeping the limitations for the users as the uses are restricted to only the processes that
can be performed by them on the application side. However they would be not be able to interact
with the server side procedures. The system is also designed for the android users only and the
application would not be responsive in the other platforms.
Secure
The security of application has been designed efficiently and also the data of the users are
guarded safely in the application. This very important for the application as the application deals
with a huge amount of data regarding the finance of the users.

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References
[1] Almurshidi, S.H. and Naser, S.S.A. Design and Development of Diabetes Intelligent Tutoring
System, 2017.
[2] Buede, D.M. and Miller, W.D. The engineering design of systems: models and methods. John
Wiley & Sons, 2016.
[3] Eastman, C.M. Building product models: computer environments, supporting design and
construction. CRC press, 2018.
[4] Wang, P. and Chung, T.S. Recent advances in membrane distillation processes: membrane
development, configuration design and application exploring. Journal of Membrane
Science, 474, pp.39-56, 2015.