Flow Ecosystem 🌊

Flow Ecosystem is a synchronized, multi-device, real-time collaboration suite. It consists of a real-time infinite whiteboard, an integrated PDF annotation engine, and a natively compiled Android application that dynamically tracks and connects to the Whiteboard across local networks.

Architecture

The ecosystem is divided into three core micro-services:

1. Flow Note (/flow_note)

The heart of the ecosystem. A real-time, infinite canvas whiteboard built on WebSockets.

• Features: Infinite panning, SVGs shapes, sticky notes, real-time synchronization.
• Network Magic: Runs an active mDNS (Bonjour) beacon that broadcasts its presence to the local Wi-Fi subnet, completely eliminating the need for manual IP configuration.
• Tech Stack: Node.js, Express, ws (WebSockets), Vanilla JS Canvas.

2. Flow PDF (/flow_pdf)

A heavily modified implementation of Mozilla's PDF.js to support seamless whiteboard integration.

• Features: Transparent UI, custom drawing/highlighting capabilities.
• Bypass Mechanics: Content-Security-Policy (CSP) and strict origin checks have been manually stripped to allow real-time cross-origin communication with the Flow Note backend.
• Auto-Sync Engine: Intercepts PDF.js blob generations and automatically pushes physical PUT requests back to the Flow Note server in the background.

3. Flow Android (/flow_android)

A native Android Java wrapper designed for aggressive local network discovery.

• Features: Sweeps the local Wi-Fi subnet with a 40-thread threadpool to dynamically hunt down the Flow Note server on Port 3939.
• Tech Stack: Pure Android Java, Gradle 8.5.

Getting Started

To spin up the ecosystem locally:

Start the Whiteboard

cd flow_note
npm install
npm start

The whiteboard will run on http://localhost:3939 and begin transmitting its IP via mDNS.

Start the PDF Engine

cd flow_pdf
npm install
npm start

The PDF server runs on http://localhost:4040.

Compile the Android App

Ensure the Android SDK is installed, then:

cd flow_android
./gradlew assembleDebug

Install the resulting .apk via ADB to your device.

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