Local-First Approaches for Cloud-Agnostic Collaborative Applications (LACCA)

This is the source code for a demonstrator developed in the context of the LACCA Softwarecampus project. LACCA explores how collaborative applications can remain responsive, resilient, and privacy-preserving by synchronizing data directly between peers and functioning fully offline. For more information see this talk in the context of the DATEV Software Craft Community.

This repo contains a Kanban-style project management application developed with local-first principles to enable collaboration without relying on centralized cloud services.

Features

• Kanban board with columns representing task states. Create, move, and edit task cards.
• Modern reactive web UI
• Offline-Functionality via local in-browser data storage (indexedDB)
• Peer to peer sync over WebRTC (browser to browser) and WebSockets (browser to server)
• Peer to peer authentication using UCAN (proof of concept)

Frontend

This is a local-first web application. Therefore, all data and the main business logic lives directly in the frontend in the browser. The frontend implements roughly the following architecture:

Development

Install npm dependencies.

  npm install

Build the scala.js project with sbt. The first build takes a bit longer because the compiler will create typed facades for the npm dependencies (see ScalablyTyped for more information on how this works). The ~ automatically recompiles the project whenever the source code changes locally.

  sbt
  sbt:kanban> ~fastLinkJS

Once you have compiled the Scala code, you can run a local dev server to view the application in action:

  npm run dev

Deployment

The project uses the Vite build tool to bundle everything into a single Javascript package that is ready for deployment. The following command will build the project and output everything into the dist folder. The output is a single page application that can be deployed using any static file server.

npm run deploy

A test version of this app is deployed at Github Pages.

Backend (Optional)

If possible, this application uses direct peer to peer connections between clients to synchronize updates over webrtc. Unfortunately, sometimes a direct client to client connection is not possible due to restrictive network environments. For these cases, this repo contains a simplistic Scala backend. The backend accepts client messages over a websocket connection and relays them to other clients.

The backend can be started using

sbt server/run