ros2bridge 0.2.0

A bridge between websocket and DDS of ROS 2

ROS WEBSOCKET BRIDGE

Overview

This is a package for converting ROS 2 DDS to websocket. This project was inspired by rosbridge_suite by Robo Web Tools. The implemented features are not for specific topics or services but all available ros interfaces. It's in early development, and not all interfaces are tested. Any bug reported will be fixed in upcoming releases.

When using the suite, I faced issues with ROS 2 and couldn't find a way to move forward. So I decided to create another which is not advanced as the suite but gets my job done. I decided to package it and publish it on PyPI for easy availability to others and learning purposes. The code I use is different, and the features are not the same. The client libraries for the suite won't work because this is not a suite clone.

Note: This project is not a suite clone. The architecture and implementation are different. Not all the features of the suite are not available in this project.

Requirements

---

• Ubuntu 20.04
• Python 3.8
• ROS 2 Foxy

Installation

---

pip3 install ros2bridge

Usage

---

python3 -m ros2bridge

optional parameters:

• -p, --port : For specific port. Default is 9020
• -n, --ngrok : By default, websocket is hosted on local-IP. If this flag is set ws is hosted internally

NOTE: for using custom ros interface source that workspace before running the bridge.

Available ROS Interfaces

---

• Publisher

TODO :

• Subscriber
• Service Client
• Action Client

Request structure

---

Publisher

{
    "operation": "publish",
    "topic": "/<topic_name>",
    "type": "<message_parent>/<message_type>",
    "message": "<message>"
}

• type eg: 'std_msgs/String'
• message eg: {"data" : "HELLO WORLD !"}
• NOTE: message should be in the format of message type

Subscriber

{
    "operation": "subscribe",
    "topic": "/<topic_name>",
    "type": "<message_parent>/<message_type>",
}

• type eg: 'std_msgs/String'

NOTE: Subscribed message will return in this format.

{
    "operation": "subscribe",
    "topic": "/<topic_name>",
    "type": "<message_parent>/<message_type>",
    "message": "<message>"
}

• type eg: 'std_msgs/String'
• message eg: {"data" : "HELLO WORLD !"}

NOTE: To unsubscribe from a topic send following message to server

{
    "operation": "subscribe",
    "topic": "/<topic_name>",
    "type": "<message_parent>/<message_type>",
    "unsubscribe": true
}

• type eg: 'std_msgs/String'

SERVICE CLIENT

For creating a service client

{
    "operation": "srv_client",
    "action": "create",
    "srv_name": "/<service_name>",
    "srv_type": "<service_parent>/<service_type>"
}

For calling a service client

{
    "operation": "srv_client",
    "action": "call",
    "srv_name": "/<service_name>",
    "srv_type": "<service_parent>/<service_type>",
    "message": "<message>"

}

• NOTE: message should be in the format of service type

ACTION CLIENT

For creating a action client

{
    "operation": "action_client",
    "action": "create",
    "action_name": "/<action_name>",
    "action_type": "<action_parent>/<action_type>"
}

For calling a action client

{
    "operation": "action_client",
    "action": "call",
    "action_name": "/<action_name>",
    "action_type": "<action_parent>/<action_type>",
    "message": "<message>"
}

• NOTE: message should be in the format of action type

Feedback from calling a action client

{
    "operation": "action_client",
    "action": "call",
    "action_response": "<action_response>",
    "action_name": "/<action_name>",
    "action_type": "<action_parent>/<action_type>",
    "message": "<message>"

}

• NOTE: message should be in the format of action type.
• NOTE: action_response will be any of 'response', 'feedback', 'result'.

QOS PROFILE

Added QoS profile to subscription. No validation of QoS is added and no error is send back to client.

Available QoS settings for subscriber:

• QoSReliabilityPolicy
• QoSDurabilityPolicy
• QoSHistoryPolicy

For creating a Qos Profile add following in addition to above request syntax

"qos" : {
    "durability": "<durability>",
    "reliability": "<reliability>",
    "history": "<history>",
}

For options to provide please refer this docs

General request will be look like

{
    "operation": "subscribe",
    "topic": "/<topic_name>",
    "type": "<message_parent>/<message_type>",
    "qos" : {
        "durability": "<durability>",
        "reliability": "<reliability>",
        "history": "<history>",
    }
}

Testing

---

For testing using tox, ROS package is required and I haven't find a way to get around it. So testing withing the system.

• MYPY
• FLAKE8
• PYTEST