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

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InventoryManagementSystem /App / Main

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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:

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UML DIAGRAM