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🛒 Styx Shopping Cart Example

This example demonstrates how to build a shopping cart microservice deployment using Styx. It combines three Styx stateful operators — order, payment, and stock — orchestrated via a Sanic-based async REST API.

Overview

The shopping cart microservice deployment example showcases:

  • A Sanic-based HTTP API as the frontend interface
  • A StateflowGraph with:
    • order_operator: creates orders and handles checkouts
    • payment_operator: manages user balances
    • stock_operator: maintains inventory and pricing
  • Full asynchronous event-driven coordination between services using remote async calls

Setup

  1. Start the Styx Coordinator and Worker, and the Locust workload client following the demo README. This will start a Styx deployment and a Sanic HTTP API as the frontend interface.

  2. Submit the dataflow graph:

POST /submit/<n_partitions>

API Endpoints

For a detailed implementation of the Sanic HTTP API refer to app.py

📦 Order

Endpoint Description
POST /orders/create/<user_key> Create a new order
POST /orders/checkout/<order_id> Attempt to complete the order
POST /orders/addItem/<order>/<item>/<qty> Add item to an order
GET /orders/find/<order_id> Lookup order state
POST /orders/batch_init/... Bulk-create sample orders

💳 Payment

Endpoint Description
POST /payment/create_user Register a new user
POST /payment/add_funds/<id>/<amt> Add credit to a user
GET /payment/find_user/<id> Fetch user credit info
POST /payment/batch_init/... Initialize many users at once

🏷️ Stock

Endpoint Description
POST /stock/item/create/<price> Create a stock item
POST /stock/add/<item>/<qty> Add inventory
GET /stock/find/<item> Lookup inventory and price
POST /stock/batch_init/... Bulk insert stock items

Operator Logic

For the implementation of the Styx operator functions refer to functions

Order Operator

  • create_order(user_id) → initializes empty cart
  • add_item(item_id, qty) → makes remote call to stock
  • checkout() → removes credit and stock remotely
  • find() → returns order state

Payment Operator

  • create_user() → zero credit
  • add_credit(amount) → modifies user balance
  • remove_credit(amount) → ensures no overdraft

Stock Operator

  • create_item(price) → zero stock
  • add_stock(amount) → increase count
  • remove_stock(amount) → raise error if insufficient
  • find_for_order() → respond with price/availability

This example highlights how Styx enables object-oriented cloud programming through fine-grained async workflows that are fault-tolerant and distributed by design.