Node.js demo reference

The Node.js demo source is on GitHub. fly launch will provide a Dockerfile and a fly.toml config file. When you make changes to your application, you can run npx @flydotio/dockerfile to produce updated Dockerfiles.

How the pieces are put together:

• The original web-dictaphone app (minus the HTML) is in the public directory, and contains icons, scripts, styles, and a web manifest; all served as static files.
• views/index.ejs contains the HTML template.
• app.js contains the server implementation, based on Express.js. There are lots of JavaScript frameworks out there, this is perhaps the oldest and most minimalist.
• The pg module is used to access PostgreSQL. Access to the database is through the DATABASE_URL secret. This module is low level which is sufficient for this demo, but most modern Node.js applications use an ORM.
• The AWS SDK for JavaScript is used to access Tigris. The following secrets are used to establish the connection: AWS_ACCESS_KEY_ID, AWS_ENDPOINT_URL_S3, AWS_REGION, AWS_SECRET_ACCESS_KEY, and BUCKET_NAME.
• The express-ws module is used for WebSocket support.
• The redis module is used to access Redis. The REDIS_URL secret is used to access the database.

Key points of logic:

• public/scripts/app.js has been modified to make server requests at various points using the Fetch API.
• app.js contains the logic to build responses to requests for the index page, and to GET, PUT, and DELETE audio clips.
• pubsub.js contains the logic to subscribe to a dictaphone:timestamp redis queue, and to forward updates to all open websocket connections.
• websocket.js contains the client implementation of web sockets. When update notifications are received, the index page is re-retrieved and the body of the DOM is replaced with new contents.
• When the WHISPER_URL secret is set, PUT requests will cause the audio clips to be passed to the Whisper server, and responses will be used to update the PostgreSQL database. The code for this is in app.js.