PlotJuggler WebSocket Client Plugin

WebSocket Client plugin to integrate remote data into PlotJuggler through a WebSocket bridge.

This plugin allows PlotJuggler to connect to a WebSocket server (for example, a custom ROS2 bridge) without requiring direct DDS or ROS2 access.

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Features

• Configurable WebSocket server connection (IP + port)
• Dynamic topic discovery
• Real-time subscribe and unsubscribe
• Remote close and reconnection handling
• Native integration within the PlotJuggler plugin system

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Architecture

PlotJuggler  <->  WebSocket Client Plugin  <->  WebSocket Server (pj_ros_bridge or similar)

The server can run on:

• The same machine
• Another laptop on the local network
• A remote robot

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Installation

1. Clone PlotJuggler

mkdir -p ~/ws_plotjuggler/src
cd ~/ws_plotjuggler/src
git clone https://github.com/PlotJuggler/PlotJuggler.git

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2. Clone the plugin inside plotjuggler_plugins

cd PlotJuggler/plotjuggler_plugins
git clone https://github.com/Alvvalencia/DataStreamWebsocketBridge.git

The final structure should look like:

PlotJuggler/
 ├── plotjuggler_plugins/
 │    ├── DataStreamWebsocketBridge/
 │    ├── ...

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3. Add the plugin to plotjuggler_plugins/CMakeLists.txt

Open:

PlotJuggler/plotjuggler_plugins/CMakeLists.txt

Add your plugin directory:

add_subdirectory(DataStreamWebsocketBridge)

Place it alongside the other plugin add_subdirectory(...) entries.

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4. Install dependencies

Ubuntu with Qt6

sudo apt install \
    qt6-base-dev \
    qt6-websockets-dev \
    libzstd-dev

Ubuntu with Qt5

sudo apt install \
    qtbase5-dev \
    qtwebsockets5-dev \
    libzstd-dev

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5. Build

cd ~/ws_plotjuggler
mkdir build
cd build
cmake ../src/PlotJuggler -DCMAKE_BUILD_TYPE=Release
make -j$(nproc)

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Usage

1. Run PlotJuggler:

./bin/plotjuggler

2. Navigate to:

Streaming → WebSocket Client

3. Configure:

   • Server IP (e.g., 192.168.1.50)
   • Port (e.g., 8080)

4. Connect.

5. Select topics and subscribe.

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Remote Connection

If the server listens on:

ws://0.0.0.0:8080

It accepts connections from any network interface.

From another machine, connect using:

ws://SERVER_IP:8080

Example:

ws://192.168.1.42:8080

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Typical ROS2 Setup

If using your ROS2 bridge:

ros2 run pj_ros_bridge pj_ros_bridge_node

Default configuration:

• Port: 8080
• Publish rate: 50 Hz

Then connect the plugin to:

ws://localhost:8080

or to the robot’s IP address.

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Connection States

The plugin handles the following states:

• Connecting
• Connected
• Disconnected
• Remote Close
• Error

If the server closes the connection, the plugin detects the event and displays a warning in the UI.

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Development

Typical plugin structure:

DataStreamWebsocketBridge/
 ├── websocket_client.h
 ├── websocket_client.cpp
 ├── websocket_client.ui
 ├── CMakeLists.txt
 └── resources/

It integrates using PlotJuggler’s DataStream interface.

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License