Add a subscriber/publisher demo for typescript

ts_demo/topics/README.md

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+# rclnodejs TypeScript Topics Demo
+
+This demo demonstrates how to use **rclnodejs** with TypeScript to create ROS2 publishers and subscribers. The demo includes a publisher that sends string messages to a topic called `ts_demo` and a subscriber that receives and displays those messages.
+
+## Features
+
+- 🚀 **TypeScript Support**: Fully typed ROS2 node implementation using rclnodejs TypeScript interfaces
+- 📤 **Publisher**: Sends timestamped string messages at regular intervals
+- 📥 **Subscriber**: Receives and displays messages with timestamps
+- 🛡️ **Type Safety**: Leverages TypeScript's type system for compile-time safety
+- 🎯 **Error Handling**: Comprehensive error handling and graceful shutdown
+- 📊 **Message Counting**: Tracks published and received message counts
+- 🎨 **Console Output**: Colorful and informative console messages
+
+## Prerequisites
+
+Before running this demo, ensure you have:
+
+1. **Node.js** (>= 16.13.0)
+2. **ROS 2** installed and sourced
+3. **rclnodejs** built and available
+
+### ROS 2 Setup
+
+Make sure your ROS 2 environment is properly sourced before running the demo:
+
+```bash
+# For example, if using ROS 2 Jazzy
+source /opt/ros/jazzy/setup.bash
+
+# Or if you have a custom workspace
+source /path/to/your/ros2_ws/install/setup.bash
+```
+
+### Verify rclnodejs Installation
+
+From the root of the rclnodejs project, ensure it's built:
+
+```bash
+cd /path/to/rclnodejs
+npm install
+npm run build
+```
+
+## Installation
+
+Navigate to this demo directory and install dependencies:
+
+```bash
+cd ts_demo/topics
+npm install
+```
+
+## Usage
+
+### Build and Run
+
+1. **Build the TypeScript code:**
+
+   ```bash
+   npm run build
+   ```
+
+2. **Run the publisher (in one terminal):**
+
+   ```bash
+   npm run start:publisher
+   ```
+
+3. **Run the subscriber (in another terminal):**
+
+   ```bash
+   npm run start:subscriber
+   ```
+
+4. **Or run both simultaneously:**
+   ```bash
+   npm run start:both
+   ```
+
+### Development Mode
+
+For development, you can run TypeScript files directly with ts-node:
+
+1. **Run the publisher:**
+
+   ```bash
+   npm run dev:publisher
+   ```
+
+2. **Run the subscriber:**
+
+   ```bash
+   npm run dev:subscriber
+   ```
+
+3. **Type check only:**
+   ```bash
+   npm run check-types
+   ```
+
+## TypeScript Setup
+
+This demo includes a self-contained TypeScript configuration that allows compilation without requiring the full rclnodejs installation to be built first. The key components are:
+
+### Local Type Definitions
+
+The `types/rclnodejs.d.ts` file provides basic TypeScript declarations for rclnodejs, enabling:
+
+- ✅ TypeScript compilation without dependencies
+- ✅ Type checking and IntelliSense support
+- ✅ Proper interface definitions for common ROS2 operations
+
+### TypeScript Configuration
+
+The `tsconfig.json` is configured to:
+
+- Use local type definitions from the `types/` directory
+- Compile TypeScript to JavaScript in the `dist/` directory
+- Generate source maps and declaration files
+- Enable strict type checking
+
+### Development vs Runtime
+
+- **Compilation**: Uses local type definitions (no rclnodejs dependency)
+- **Runtime**: Requires actual rclnodejs installation and ROS 2 environment
+
+## Expected Output
+
+### Publisher Output:
+
+```
+Starting TypeScript Publisher Demo...
+✓ rclnodejs initialized
+✓ Created node: /ts_publisher_demo
+✓ Created publisher on topic: ts_demo
+✓ Created timer with 1000ms interval
+🚀 Publisher is running. Press Ctrl+C to stop...
+
+📤 Published: "Hello from TypeScript publisher! Message #1 at 2025-07-16T10:30:00.123Z"
+📤 Published: "Hello from TypeScript publisher! Message #2 at 2025-07-16T10:30:01.125Z"
+📤 Published: "Hello from TypeScript publisher! Message #3 at 2025-07-16T10:30:02.127Z"
+...
+```
+
+### Subscriber Output:
+
+```
+Starting TypeScript Subscriber Demo...
+✓ rclnodejs initialized
+✓ Created node: /ts_subscriber_demo
+✓ Created subscription on topic: ts_demo
+👂 Subscriber is listening. Press Ctrl+C to stop...
+
+📥 [1] Received: "Hello from TypeScript publisher! Message #1 at 2025-07-16T10:30:00.123Z"
+    Timestamp: 2025-07-16T10:30:00.124Z
+📥 [2] Received: "Hello from TypeScript publisher! Message #2 at 2025-07-16T10:30:01.125Z"
+    Timestamp: 2025-07-16T10:30:01.126Z
+...
+```
+
+## Project Structure
+
+```
+ts_demo/topics/
+├── package.json          # Project dependencies and scripts
+├── tsconfig.json         # TypeScript configuration
+├── README.md            # This file
+├── src/                 # TypeScript source files
+│   ├── publisher.ts     # Publisher implementation
+│   └── subscriber.ts    # Subscriber implementation
+└── dist/               # Compiled JavaScript (after build)
+    ├── publisher.js
+    └── subscriber.js
+```
+
+## Code Explanation
+
+### Publisher (`src/publisher.ts`)
+
+The publisher demonstrates:
+
+- **Node Creation**: Creates a ROS2 node using TypeScript
+- **Publisher Setup**: Creates a publisher for `std_msgs/msg/String` messages
+- **Timer Usage**: Uses `node.createTimer()` for periodic message publishing
+- **Message Creation**: Uses `rclnodejs.createMessageObject()` with proper typing
+- **Graceful Shutdown**: Handles SIGINT for clean shutdown
+
+Key TypeScript features used:
+
+```typescript
+import * as rclnodejs from 'rclnodejs';
+
+const node = new rclnodejs.Node('ts_publisher_demo');
+const publisher = node.createPublisher('std_msgs/msg/String', TOPIC_NAME);
+const message = rclnodejs.createMessageObject('std_msgs/msg/String');
+```
+
+### Subscriber (`src/subscriber.ts`)
+
+The subscriber demonstrates:
+
+- **Subscription Creation**: Creates a typed subscription for string messages
+- **Callback Handling**: Processes incoming messages with proper TypeScript typing
+- **Message Processing**: Displays received messages with timestamps
+
+Key TypeScript features used:
+
+```typescript
+const subscription = node.createSubscription(
+  'std_msgs/msg/String',
+  TOPIC_NAME,
+  (message: rclnodejs.std_msgs.msg.String) => {
+    console.log(`Received: "${message.data}"`);
+  }
+);
+```
+
+## TypeScript Benefits
+
+This demo showcases several TypeScript advantages:
+
+1. **Type Safety**: Compile-time checking prevents common errors
+2. **IntelliSense**: Better IDE support with autocompletion
+3. **Interface Definitions**: Clear contract definitions for ROS2 messages
+4. **Refactoring Safety**: Easier to maintain and modify code
+5. **Documentation**: Types serve as inline documentation
+
+## Troubleshooting
+
+### Common Issues
+
+1. **Module not found error for 'rclnodejs':**
+
+   ```
+   Cannot find module 'rclnodejs' or its corresponding type declarations
+   ```
+
+   **Solution**: Ensure you're in the correct directory and rclnodejs is properly linked:
+
+   ```bash
+   cd ts_demo/topics
+   npm install
+   ```
+
+2. **ROS 2 environment not sourced:**
+
+   ```
+   Error: Unable to find ROS 2 installation
+   ```
+
+   **Solution**: Source your ROS 2 setup file:
+
+   ```bash
+   source /opt/ros/jazzy/setup.bash
+   ```
+
+3. **Build errors:**
+   ```
+   TypeScript compilation errors
+   ```
+   **Solution**: Check TypeScript configuration and ensure all dependencies are installed:
+   ```bash
+   npm install
+   npm run clean
+   npm run build
+   ```
+
+### Debugging Tips
+
+1. **Enable verbose logging:**
+
+   ```bash
+   export RCUTILS_LOGGING_SEVERITY=DEBUG
+   ```
+
+2. **Check ROS 2 topic list:**
+
+   ```bash
+   ros2 topic list
+   ros2 topic echo /ts_demo
+   ```
+
+3. **Monitor topic info:**
+   ```bash
+   ros2 topic info /ts_demo
+   ```
+
+## Customization
+
+You can easily customize this demo:
+
+### Change Topic Name
+
+Edit the `TOPIC_NAME` constant in both files:
+
+```typescript
+const TOPIC_NAME = 'your_custom_topic';
+```
+
+### Change Message Type
+
+To use a different message type, update the type string and interface:
+
+```typescript
+// For example, using geometry_msgs/msg/Twist
+const publisher = node.createPublisher('geometry_msgs/msg/Twist', 'cmd_vel');
+const message = rclnodejs.createMessageObject('geometry_msgs/msg/Twist');
+```
+
+### Adjust Publishing Rate
+
+Modify the `PUBLISH_INTERVAL` in the publisher:
+
+```typescript
+const PUBLISH_INTERVAL = 500; // Publish every 500ms
+```
+
+## Next Steps
+
+After running this demo, you might want to explore:
+
+1. **Different Message Types**: Try using other ROS2 message types like `geometry_msgs/msg/Twist`
+2. **Services**: Implement ROS2 services with TypeScript
+3. **Actions**: Create action servers and clients
+4. **Parameters**: Use ROS2 parameters in your TypeScript nodes
+5. **Lifecycle Nodes**: Implement managed lifecycle nodes
+
+## Contributing
+
+This demo is part of the rclnodejs project. To contribute:
+
+1. Fork the rclnodejs repository
+2. Create a feature branch
+3. Make your changes
+4. Add tests if applicable
+5. Submit a pull request
+
+## License
+
+This demo is licensed under the Apache License 2.0, same as the rclnodejs project.

ts_demo/topics/package.json

@@ -0,0 +1,37 @@
+{
+  "name": "rclnodejs-ts-topics-demo",
+  "version": "1.0.0",
+  "description": "TypeScript demo for rclnodejs topics (publisher and subscriber)",
+  "main": "index.js",
+  "scripts": {
+    "prebuild": "npm run clean",
+    "build": "tsc",
+    "start:publisher": "npm run build && node dist/publisher.js",
+    "start:subscriber": "npm run build && node dist/subscriber.js",
+    "start:both": "npm run build && concurrently \"node dist/publisher.js\" \"node dist/subscriber.js\"",
+    "clean": "rimraf dist",
+    "dev:publisher": "ts-node src/publisher.ts",
+    "dev:subscriber": "ts-node src/subscriber.ts", 
+    "check-types": "tsc --noEmit"
+  },
+  "keywords": [
+    "rclnodejs",
+    "ros2",
+    "typescript",
+    "publisher",
+    "subscriber", 
+    "demo"
+  ],
+  "author": "rclnodejs contributors",
+  "license": "Apache-2.0",
+  "devDependencies": {
+    "@types/node": "^22.16.4",
+    "concurrently": "^9.2.0",
+    "rimraf": "^6.0.1",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.8.3"
+  },
+  "dependencies": {
+    "rclnodejs": "file:../../"
+  }
+}