First, let us know what an LLD is. Low-level design (LLD) is an internal component level logical design process that can be utilized for designing data structures, performance algorithms, source code, and the necessary software architecture through a step by step refinement procedure. Now it can be clearly understood as to why we should be knowing about the working of LLD. Let us now analyze the challenges for this LLD and how these hotel booking low-level designs of such particular systems are created.

1. Is Hotel Booking LLD as Simple as in the
Applications?
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You must wonder how the hotel booking applications work. How does
the hotel booking application design finds us the best options after comparing
every competing hotel room prices & offers and provide us with the best
results? After all, what happens in the back end of such square hotel booking
system design applications? There are several hotel reservation systems such

2. as OYO, Trivago, Hotels.com, and several more websites and applications
which consider various aspects of the System Design hotel reservation
system we might be familiar with. There are several tasks that need to be
carried out by these high-level system design and hotel reservation systems
like price comparison, booking required rooms, availability, ratings, payment,
etc. which are finely designed to go hand in hand along with hotel booking
low-level designs for every sub-system.
First, let us know what an LLD is. Low-level design (LLD) is an internal
component level logical design process that can be utilized for designing data
structures, performance algorithms, source code, and the necessary software
architecture through a step by step refinement procedure. Now it can be
clearly understood as to why we should be knowing about the working of LLD.
Let us now analyze the challenges for this LLD and how these hotel booking
low-level designs of such particular systems are created.
Planning and Sorting out The Skeleton
Let us consider the task of the reservation of a room for a particular system. A
popular design pattern that is deployed for such applications is Object
Relational Mapping (ORM) which is a class structure used on the basis of how
we have used the database structure. This pattern favors rationality between
the data and the design. We require to understand the database schema to
proceed further with either LLD or DLD. Also, we need to consider the
following database tables: ● Guests (which can only be booked when the user
is booking the same) ● Room (the particular type of room the user chooses to
book)
● Hotel (the rooms should belong to a respective hotel)
● Reservation (the reservations need to be tracked down and stored as well)
● Payment, that can be made through several modes or in certain ways like
partial, complete, or, with or without an advance.
Let us now see what each of these fields should have in them as their
elements and make a database using SQL as we need to store all the
information in a tabular form for our benefits of finding the information in an
organised way. Later, you can find that somehow all fields are interconnected
to each other through either one or many of each of their elements.
1. User or Guest:

3. If we dig into the details of the "user" database description, we would find
various details under the name user_id, like first name, last name, location,
and phone number each of which corresponds to a certain data type.
fig. 1
2. Room:
Similarly, we have the room database which can be classified as per the room
type or its capacity along with the facilities it consists of, like heater, wifi, air
conditioner, etc. It can also hold information like if the room is sea facing, or
has a hilltop view, etc.
fig. 2

4. 3. Hotel:
Then the hotel database can consist of its location and the owner's details. It
needs to have a list of the type of rooms the hotel consists of and it needs to
make sure the rooms belong to their respective hotels and also store the
information of the rooms which are booked or occupied or unreserved. fig.
3 ###4. Reservation:
Further, the reservation database would be a combination of the information
entered by the user mentioning check-in and check-out timings and payment
details, and also the room type. Designing a checklist for all the payment
transactions can be done by following the normalization rule for SQL as it has
to be associated with the revervation_id so that all the transactions made by
the user come under this domain. ** fig. 4**
5. Transaction:
For all the payment transactions done by the user is now to be stored along
with the amount linked to the transaction_id. This should also store the type of
method used for payment by the user be it cash, card, UPI, etc. or if there is
any offer or coupon code applicable with the terms and conditions. fig. 5
6. Payment:

5. For this to be recorded appropriately, each tuple is required to make a
connection between booking_id with the analogous transaction_id. fig. 6
Square Hotel Booking System Design
We can make a hotel management system project design decision to hold the
transaction updates in the form of a list or a separate table linked with the
reservation database with multiple tuples for each payment transaction. The
separate table linked with the reservation database is an application of
the Normalization rule for SQL though the list way reduces the additional
query processing. It is preferable to use the tabular method. The transaction
table holds the information about the amount being transferred. Lastly, the
payment database connects the payments made with the associated
transaction as mentioned above. The application can be made further user-
friendly by accepting cancellations depending on certain terms and conditions.
The flowchart represented in the figure below is to be noted with the help of
the following schema:
● reservation -> user (1:1)
● room -> hotel (many:1)
● reservation -> payment (1: many)
● payment -> transaction (1:1)
● reservation -> room (1: many)
● reservation -> hotel (1:1)
● reservation -> room type (1: many)
● reservation -> room type rooms (1:1)
fig. 7
Hotel Booking Program in Java

6. If we wish to prepare an Object Oriented Programming design for an
online hotel booking program in Java, one needs to create certain classes and
attributes which would hold information with the corresponding datatype.
● We shall introduce a class ‘user’ which shall hold the user's Information like
user_id, name, date of birth, mobile number, email ID, gender and other such
personal information.
● Then there would be a class ‘Room’ that shall hold information like the
room_id, hotel_id, room's type and availability.
● Then the class ‘hotel’ shall hold information like the list of rooms, address,
facilities provided and other such information regarding the hotel.
● Further, the ‘booking’ class would hold information about the user, the hotel,
list of rooms, payment status, and booking time and duration.
● The class ‘address’ would hold the address of the hotel.
● Lastly, there shall be a class ‘duration’ to hold information about the time of
stay required for the booking.
Each of these classes shall hold the data with the specified data types which
can be manipulated as per the response demanded from the user's end. The
access should also be given to the manager or any other higher or reserved
authority so that the hotel information can be updated like prices, more
pictures, or facilities. This is just a basic algorithm for the application, on
desired, more elements can be added and linked to make it as user-friendly
as possible.
Conclusion
The above article portrays what happens at the backend of any hotel booking
application. Everything here is done to make a website or application as
appealing as possible. We discussed the challenges and necessities to be
kept in mind for the system LLD, then a skeleton to plan an application out,
and lastly a Java algorithm to give the application a complete outlook.
Whether or not you belong to the Computer Science field, you must know
these trends and updates such as LLD applications and Java. For deeper
learning or if you want to express your ideas in a canvas of application you
could refer to Skillslash courses like Full Stack Development Course In

7. Bangalore and Data Science Course In Pune with placement, workshops to
stay updated and broaden your horizon of thinking and implementing.