BuyIt System: Comprehensive Z Schema Operations and Application Design

This project presents the design and functionality of the BuyIt system, an online marketplace, using Z schema. The system is designed to facilitate user registration, login, product uploading, searching, and purchasing. It incorporates access control strategies and business continuity plans to ensure security. The Z schema operations detail the inputs and outputs for processes like user registration, login, product uploading, and searching, including preconditions and postconditions for each operation. The system includes an alert schema to manage user status based on actions and reputation, alongside functionalities for purchasing products and updating user reputations. The paper also addresses user punishment for low reputation and incorporates security measures to maintain data confidentiality, integrity, and availability. The schema uses variables like email, password, and status to ensure secure and efficient transactions and user management. The system is designed to be a reliable marketplace for both sellers and buyers, with an aim to increase business revenue through an online platform.

Running Head: SOFTWARE METHODOLOGIES 1
Software Methodologies
Institution
Date
Name

SOFTWARE METHODOLOGIES 2
Contents
Overview.....................................................................................................................................................3
Z Schema Operations...................................................................................................................................3
Initialization.............................................................................................................................................4
Register a new user.................................................................................................................................4
Login........................................................................................................................................................5
Upload Product Details............................................................................................................................6
Search for a product................................................................................................................................7
Alert Schema...........................................................................................................................................7
Purchasing products....................................................................................................................................8
Update Reputation..................................................................................................................................9
Punishing a user.....................................................................................................................................10
References.................................................................................................................................................10

SOFTWARE METHODOLOGIES 3
Overview
Many business processes in the 21st Century happen through the internet. The latest web
technologies allow for users to look for products online and purchase them with just a click of
the button (Fang, Sun, McCole, Ramsey & Lim, 2014). Retailers, on the other hand, are allowed
to upload and make their products available to users worldwide. BuyIt is a system that has been
conceptualized to make these business processes as simple and efficient as possible. BuyIt
adheres to all cybersecurity regulations with the goal of keeping user data secure all the time.
This management system implements access control strategies together with business continuity
plans such as data backups to ensure the system is never compromised. The main objective of
BuyIt is to provide a reliable marketplace for sellers and buyers to list, sell and purchase
products. BuyIt also aims at augmenting business revenue from an online platform
Z Schema Operations
The BuyIt schema developed in this paper defines the inputs and output variables which
are required by the robust system to complete day to day procedures such as user registration,
login, recording user reputation, uploading new products to the portal, searching products,
purchasing products and punishing users who have lower reputation levels.
The parameters listed below will be utilized in determining the completion of behavior
and actions.
Email: this is the user’s email address which will be used for signing in.
Password: this is the user’s private identification text used for authentication during sign
in.
State: this is the state of the user’s sign in (Whether Online or Offline)

SOFTWARE METHODOLOGIES 4
Reputation: Utilized in determining the status of a user.
Status: This is the usability of the user, i.e. whether Active or Blocked
Six alert point: This represents a serious alert that the user account has been declined or
blocked.
Initialization
Init
Δ BuyIt
hwm = 0
Register a new user
Register_new_user
Ξ BuyIT
name? :USERNAME
email? :EMAILADDRESS
pass? :PASSWORD
if name? ∉ known ∧ email? ∉ known
then pass ′ = password ∪ {email?↦password?}
else name? ∨ email ?= already exists
The precondition in this schema is that the username and email are not already in the
BuyIt database that is name? ∉ known ∧ email? ∉ known. If the same email or username is
found existing in the BuyIt database, the user will be asked to provide different credentials.
After registering to the system using a unique email and a strong password, the user will
have to log in so as to gain access to the various modules.

SOFTWARE METHODOLOGIES 5
Every online business in this technological times must implement perfect security
strategies in order to ensure that the CIA triad is achieved. The CIA triad stands for is
Confidentiality, Integrity, and Availability. Large business enterprises are always a target for
cybercriminals. In order to help prevent a data breach and user impersonation, BuyIt has
deployed a perfect access control technology that ensures that every user must be authenticated
before using the BuyIt services. The user password and email are encrypted in the database in
order to keep the confidentiality of data even when the database is accessed by cybercriminals.
The login schema below illustrates the sign in process
Login
Login
Email: EMAILADDRESS
Pass: PASSWORD
Stat: STATE
Status_user: STATUS
If email ∈ EMAILADDRESS ∧ pass ∈ PASSWORD ∧ Status_user ≠ Blocked
Then stat = Online
Else stat = Offline
Before a product is seen by a potential buyer, it must be uploaded by the seller with its
subsequent specifications. In the schema below, the seller must indicate the price, location, and
specification of the product in order to successfully upload it. This is clearly noted by the

SOFTWARE METHODOLOGIES 6
predicate conditions in the schema, e.g. “price? = not null, condition? = not null” (Bowen,
2016).
Upload Product Details
The upload product schema below allows for input from the user on elements like
PRODUCTNAME, PRODUCTSPECIFICATION, PRODUCTCONDITION, PRICE, and
POSTAGE location. The preconditions on this schema are that the user must provide the
PRODUCTPRICE, PRODUCTSPECIFICATION, and PRODUCTCONDITION in order for
their new product to be uploaded successfully.
Upload_product_details
ΔBuyIt
Name? :PRODUCTNAME
Specification? :PRODUCTSPECIFICATION
Condition? :PRODUCTCONDITION
Price? :PRODUCTPRICE
Location? :POSTAGE
Name? ∈ known ∨ ∉ known
Price? = NotNull
Condition? = NotNull
Specification? = NotNull
hwm′ = hwm + 1
products′ = products ⊕ {hwm′ ⦁ name?}
price′ = prices′ ⊕ {hwm′ ⦁ price?}
condition′ = conditions′ ⊕ {hwm′ ⦁ condition?}
hwm′ = hwm + 1
products′ = products ⊕ {hwm′ ⦁ name?}
price′ = prices′ ⊕ {hwm′ ⦁ price?}
specification′ = specifications′ ⊕ {hwm′ ⦁ specification?}

SOFTWARE METHODOLOGIES 7
Search for a product
The BuyIt web application software is a large information system that will keep records
of several user products from all domains. Therefore, when a buyer wants to purchase, they will
not have to spend their lifetime scrolling through all the available products on the portal. We
have implemented a function that will assist users to search for the product they want by using
three keywords: PRODUCTNAME, PRODUCTPRICERANGE, and the
PRODUCTLOCATION.
In the schema, there are a few pre-conditions. The PRODUCTNAME must be known, the
PRICERANGE must be known, and the LOCATION must be known as well. These items must
be found in their respective arrays in order to guarantee a successful search.
Search_product
ΞBuyIt
Name? :PRODUCTNAME
Price_range? :PRODUCTPRICERANGE
Location? :PRODUCTlOCATION
Name? ∈ known
Price_range? ∈ known
Location? ∈ known
Specification! = PRODUCTSPECIFICATION
Condition! = PRODUCTCONDITION
If name? ∉ known
Then result! = not_known
Alert Schema
This is where the status of a user is changed whenever they undertake unlawful actions,
or their reputation is lower than 1.

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Alert
ΔBuyIt
Status_user: STATUS
Alert: level_of_alert
If alert = level_of_alert
∨ alert = One level_of_alert
∨ alert =Two level_of_alert
Then status_user =ActiveState
Else status_user BlockedState
Purchasing products
Users are able to make purchases using their credit card numbers. The system will
calculate the amount needed for payment. The pre-conditions here are that the credit card
balance is not less than the total cost of the product and the user must be active to purchase an
item (Bowen, 2016)). Further, the item quantity status must be available.
Product_purchase
ΔBuyIt
Alert: ALERTPOINT
Bal4: BALANCE
Qua:QUANTITY
Shipping: POSTAGECHARGE
Bal3: ℕ
Productprice:ℕ
If stat =Online
∧ user_status ≠ Blocked
∧ Alert ≠ Six alert point
∧ Bal4 ≠ ZeroBalance
∧Qua = Available
then Bal3 = productprice + shipping
bal4 = bal4 – bal3
else user_status = blocked

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Update Reputation
Every time a purchase is made, the seller and buyer will be prompted to give the
reputation score of their correspondent. The score should be ≤0 and ≤ 5. When the score of a user
is less than 1, they are blocked from using the system.
Update_reputation
ΔBuyIt
Reput_seller? :REPUTATIONOFSELLER
Reput_buyer? :REPUTATIONOFBUYER
Prev_buyer_reput: ℕ
Prev_seller_reput: ℕ
Reput_seller: ℕ
Reput_buyer: ℕ
let six alert point = userisblocked
if stat ≠blocked
then ( (reput_buyer + prev_buyer_reput) ÷ 2 = reput_buyer)
then ( (reput_seller + prev_seller_reput) ÷ 2 = reput_seller)
else Six alert point

SOFTWARE METHODOLOGIES 10
Punishing a user
Reput_buyer! And reput_seller! In the schema below is the output of the user’s
reputations. If the reputation falls below 1, the status of the user changes to blocked (user_stat =
blocked)
Punnish_user
Reput_buyer! = BUYERREPUTATION
reput_seller! = SELLERREPUTATION
if reput_buyer ∧ reput_seller < 1
then user_stat = blocked
else user_stat = Active
References
Bowen, J. P. (2016). The Z Notation: Whence the Cause and Whither the Course?.
In Engineering Trustworthy Software Systems (pp. 103-151). Springer, Cham.
Fang, Y., Qureshi, I., Sun, H., McCole, P., Ramsey, E., & Lim, K. H. (2014). Trust, Satisfaction,
and Online Repurchase Intention: The Moderating Role of Perceived Effectiveness of E-
Commerce Institutional Mechanisms. Mis Quarterly, 38(2).