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PlotJuggler WebSocket Client Plugin

plotjuggler_plugins/DataStreamPlotJugglerBridge/README.md

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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.

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

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

Installation

1. Clone PlotJuggler

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

2. Clone the plugin inside plotjuggler_plugins

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

The final structure should look like:

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

3. Add the plugin to plotjuggler_plugins/CMakeLists.txt

Open:

PlotJuggler/plotjuggler_plugins/CMakeLists.txt

Add your plugin directory:

cmake
add_subdirectory(DataStreamWebsocketBridge)

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

4. Install dependencies

Ubuntu with Qt6

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

Ubuntu with Qt5

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

5. Build

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

Usage

  1. Run PlotJuggler:
bash
./bin/plotjuggler
  1. Navigate to:
Streaming → WebSocket Client

  1. Configure:

    • Server IP (e.g., 192.168.1.50)
    • Port (e.g., 9090)

  2. Connect.

  3. Select topics and subscribe.

Remote Connection

If the server listens on:

ws://0.0.0.0:9090

It accepts connections from any network interface.

From another machine, connect using:

ws://SERVER_IP:9090

Example:

ws://192.168.1.42:9090

Typical ROS2 Setup

If using your ROS2 bridge:

bash
ros2 run pj_ros_bridge pj_ros_bridge_node

Default configuration:

  • Port: 9090
  • Publish rate: 50 Hz

Then connect the plugin to:

ws://localhost:9090

or to the robot’s IP address.

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.

Development

Typical plugin structure:

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

It integrates using PlotJuggler’s DataStream interface.

License