This is a Next.js-based application.

Why NextJS for an API?

NextJS was used because I (Nathan) am a frontend developer by trade, and this is the API tool I have been most familiar with over the last few years. It can quite work well as a part of a full-stack JS application, typically as a backend-for-frontend api. It's also handy for displaying the corresponding Swagger docs (available at the root application path, see below).

Scaling the app

The app takes supplied images, and saves them locally to the filesystem. Secure coding is limited to sanitized query params ("tag" and "filename") and filenames themselves. If this were scaled or used in production, the system would need to have some understanding of users and auth, as well as transporting, storing and retrieving files safely and securely.

Uploaded DICOM and generated PNG images files are being stored in public/assets/.

API Documentation

OpenAPI spec is available at http://localhost:3000/api/v1/openapi.json once the application is running (see below).

Swagger is running at the web-app root, for your convenience.

Postman Collection

To help with development and integration testing, I used a Postman collection. For your convenience, it is available in public/docs/PocketHealth API.postman_collection.json

Unit Tests

The test instructions didn't explicitly ask for unit-test, but I do believe they are good practice. At the same time, I didn't want to get bogged-down in writing a ton for this exercise, in the interest of time. Instead, I added Jest (a JS-based test lib), and mocked up a few simple tests to prove the concept, and also to help with test-driven development of a couple functions I wanted to validate.

To run the tests, install the app per the instructions belowm, and then run npm run test in the command-line.

Running the Application: "Get Started"

First, download the application:

git clone https://github.com/nathanyarnold/dicom_api.git
cd dicom_api
npm install

Second, install the application:

npm install

Third, run the development server:

npm run dev

Fourth (optional), run the unit-test suite

npm run test

Open http://localhost:3000 with your browser to see the Swagger Docs and interact with the API.

The API is running at:

• POST /api/v1/file (Upload a DICOM file)
• GET /api/v1/file/headers (Retrieve all DICOM headers from a local file)
• GET /api/v1/file/header/{tag} (Retrieve a DICOM header value)
• POST /api/v1/file/png (Create a PNG file from a DICOM file)
• GET /api/v1/file/png (Retrieve the PNG file)

Some additional Utils are available at:

• GET /api/v1/openapi (Retrieve OpenAPI Specification)
• GET /api/v1/health (Health check endpoint)
• GET /api/v1/ping (Health check endpoint)