🧾 Purchase Processing Pipeline (Azure Functions + Azurite)

A simple event-driven sample demonstrating how to process queue messages locally using Azure Functions and the Azurite Storage Emulator.

This project simulates a lightweight purchase processing flow entirely on your local machine — perfect for experimenting with queue triggers and output bindings.

🧱 Architecture Overview

Azurite Queue (purchases)
        ↓
Azure Function (ProcessPurchase)
        ↓
Azurite Queue (purchases-processed)

QueueMessageSender – Console app that sends purchase messages to the purchases queue.
PurchaseProcessor – Azure Function project that processes messages and writes results to the purchases-processed queue.

⚙️ Prerequisites

.NET 8 SDK
Azurite
(VS Code extension or Docker)
Azure Functions Core Tools v4
Azure Storage Explorer
(optional, for viewing queues)

🚀 Getting Started

1. Start Azurite: VS Code extension

Press Ctrl+Shift+P → Azurite: Start

2. Run the QueueMessageSender

This console app creates and sends mock purchase messages to Azurite.

cd QueueMessageSender
dotnet build
dotnet run

You’ll be prompted for:

Customer name
Number of items
Name, quantity, and price for each item

A message is then sent to the purchases queue.

3. Start the Function App

The function listens for new messages on the purchases queue, processes them, and outputs to purchases-processed.

cd PurchaseProcessor
func start

If you’re running plain JSON (not Base64), make sure your host.json includes:

{
  "version": "2.0",
  "extensions": {
    "queues": {
      "messageEncoding": "none"
    }
  }
}

4. View Messages

Use Azure Storage Explorer to connect to your local Azurite instance and inspect both queues:

purchases – input queue
purchases-processed – processed output messages

🧩 How It Works

QueueMessageSender sends a JSON message like:

{
  "PurchaseId": "43ecd0e5-7f2d-4c5a-a5bc-9877783a61bf",
  "CustomerId": "Customer-Id-01",
  "Items": [
    { "Name": "Book", "Quantity": 1, "Price": 9.99 }
  ],
  "Timestamp": "2025-11-06T14:27:47.4503265Z"
}

The Function App:

Logs receipt of the message
Deserializes the JSON
Adds a processed timestamp
Writes the updated record to purchases-processed

⚠️ Notes

If message processing fails more than 5 times, it’s automatically moved to a poison queue named purchases-poison.
Both input and output queues are fully emulated in Azurite — no Azure resources required.

🧰 Project Structure

.
├── QueueMessageSender/      # Console app to send queue messages
├── PurchaseProcessor/       # Azure Function project
│   ├── ProcessPurchase.cs   # Queue trigger function
│   └── host.json            # Function host configuration
└── README.md

🏁 Summary

This project demonstrates a local-first, event-driven workflow using:

Azurite for queue emulation
Azure Functions (in-process model)
A simple console producer and consumer pattern

It’s a great foundation for experimenting with Azure Functions, message processing, and building local prototypes before deploying to the cloud.

mcawalsh/functionapp-purchase-processor