Reactive Social Network Service (Proof of Concept)

This repository demonstrates a minimal reactive programming system using Skip and TypeScript to simulate a basic social network use case. The goal is to keep things simple, inspectable, and educational.

“The simpler, the merrier.”

🧠 What It Does

We build a tiny reactive service to track "active friends" in social groups. It:

• Defines users and groups as reactive data.
• Tracks active users and friend connections.
• Uses Skip to auto-update data dependencies.
• Exposes a small REST API using Express.

Example:

We show how Alice’s list of active friends updates live as data changes, no manual refresh needed.

---

📁 Project Structure

src/
├── activefriends.mts   # Mappers & resources to track active friends
├── data.mts            # Initial user and group data
├── index.ts            # Express server exposing API
├── skipservice.mts     # Skip service and reactive graph
└── types.mts           # Type definitions and Skip interfaces

🚀 Getting Started

1. Clone the Repo

git clone https://github.com/SkipLabs/reactive_social_network_service_poc
cd reactive_social_network_service

2. Install Dependencies

npm install

3. Build the Project

npm run build

4. Start the Service

npm run start

You should see:

Skip control service listening on port 8081
Skip streaming service listening on port 8080
Groups REST wrapper listening at port 8082

🔍 Try It Out

1. Listen to Alice’s Active Friends

In a new terminal:

curl -LN http://localhost:8082/active_friends/1

2. Update Alice's Friends (e.g., Add Eve)

In a third terminal:

curl http://localhost:8081/v1/inputs/users \
  -X PATCH \
  --json '[[1, [
    {
      "name": "Alice",
      "active": true,
      "friends": [0, 2, 3]
    }
  ]]]'

You’ll see reactive updates in the second terminal!

⚙️ NPM Scripts

npm run build: Compile TypeScript files into dist/ npm run start: Launch the Express and Skip services npm run clean: Remove dist/ and node_modules

🧩 Tech Stack

• TypeScript
• Node.js
• Skip – for reactive data flows
• Express – lightweight REST API server