LLD Inventory Management System for Blinkit/Dunzo/Zepto

Problem Statement

In the following blog post, we will discuss low Level Design architecture of an Inventory Management System used by Blinkit/Dunzo/Zepto for groceries delivery

Let us start by identifying the objects and encapsulating their attributes and operations into classes

Identification of all Objects and Classes

ProductUnit

Represents an individual entity of a Product
- It has its expiry date , serialNumber manufactured from the factory

Product

Has a list of all ProductUnits which are all the same product, this can also be seen as a ProductUnitsController

Inventory

Inventory has a list of all products
- I can add new Products, new units for this product and other similar CRUD operations

Warehouse

Has a single instance of inventory and manages the inventory

WareHouseController

As our system can have many warehouses, we need a warehouse controller for their management, our assumption being at a time only one warehouse delivers to the customer
- The WareHouseController selects a single warehouse using a WarehouseSelectionStrategy
WarehouseSelectionStrategy and NearestWarehouseSelectionStrategy and so on ...
- We use the Strategy pattern to pick the strategy that controller uses to select warehouse at runtime

User

Has a Cart and a list of Order IDs representing order history

UserController

There can be many users so we have to maintain a user controller

Cart

Maintains a list of Products and their quantity

Order

Fetches the user's cart and converts that into an order with Invoice and Payment

OrderController

Since there can be many Orders, they need to be controlled by an OrderController

InventoryManagementSystem /App / Main

User Flow

The InventoryManagementSystem takes in a list of registered users and warehouses present in the system for system initialisation
We create a function `runDeliveryFlow` to test the entire flow of the application
The initialisation for users and warehouses can be done as follows: