Only released in EOL distros:   electric fuerte groovy

Deprecated

This is the documentation for the 1.0 version of rosbridge. This version blazed the trail and helped us establish use cases and applications. However, it is now considered deprecated and is not currently supported.

For the currently maintained version of rosbridge, please see rosbridge 2.0.

Introduction

rosbridge makes ROS topics and services available over either pure TCP sockets or web-sockets as JSON messages. Both modes, socket and web-socket, use the same JSON format for both request and responses. A single instance of rosbridge supports both modes among different clients simultaneously.

ros.js

The rest of this page describes the rosbridge server itself. If you are mostly interested in writing pure HTML+JS ROS applications, you will probably only care about rosbridge insomuch as it is the backend to ros.js. You should probably start by reading the ros.js tutorial.

Socket modes

By default, rosbridge listens on port 9090 and supports two connection modes.

web-sockets

rosbridge supports the normal web-socket handshake for connection initiation. After a connection is established JSON messages (see the message format section) are exchanged as normal web-socket messages.

sockets

To start a socket connection with rosbridge, open a socket to port 9090 of the appropriate host and send the string "raw" followed by a carriage return, a linefeed, another carriage return, and another linefeed (i.e. "raw\r\n\r\n" in python).

After that, all message to or from the server should/will begin with a 0x00 byte and end with 0xFF.

Message Format

Messages to and from rosbridge are in the form of pure ASCII JSON messages.

Topics

Topics are sent and received in the following format:

{"receiver":"/topic","msg":{},"type":"package/Type"}

where /topic is the topic, msg contains a JSON version of the actual ROS message, and type contains the type string for the topic.

For example, sending a Twist message to /cmd_vel might look like this:

{"receiver":"/cmd_vel","msg":{"linear":{"x":0,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}},"type":"geometry_msgs/Twist"}

Service Calls

To make a service call:

{"receiver":"/service","msg":[]}

where receiver is the service being called and msg is a JSON array of arguments (e.g. [arg1,arg2]). Answers will come back from rosbridge as topics with the receiver set to the name of the service.

JSON forms of ROS Messages

For the most part, the translation of ROS to JSON is straight-forward. However, some ROS types (such as images) can optionally be translated into special forms such as data-uri's. For more details, see the rosbridge Javascript tutorial.

Special Services

The special services portions of the rosjs binding for rosbridge are always available, even when rosbridge is being accessed from another language or over pure sockets. These services are how rosbridge clients discover and subscribe to topics, discover services, and perform other tasks. For a full description of these services read the "rosjs Services" section of the Javascript rosbridge tutorial.

Writing a rosbridge client

The rosbridge protocol was designed to make writing clients simple. We recommend you examine the source to ros.js, a full web-socket client implemented in only 73 lines.