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Gazebo 9.0.0 Release

2018-01-25

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Changelog | Migration Guide | Roadmap

Release Highlights

We are proud to announce the release of Gazebo 9. This version of Gazebo has long term support with an end-of-life on January 25, 2023.

An ongoing effort over the past few years has been to break out Gazebo's internal libraries into a set of libraries under the Ignition Robotics project. These libraries will move Gazebo away from a large monolithic code base. An additional goal is to increase development transparency and adoption of features that may have been hidden behind the veil of Gazebo.

While still in the early stages of development, a few of the Ignition libraries are ready for broad public consumption. These libraries include Ignition Math, Messages, and Transport. Libraries higher on the dependency stack, such as Rendering, Sensors, Physics, and GUI will see progress toward 1.0 releases over this year.

The 2018 roadmap for Gazebo and the Ignition libraries will be forthcoming in the next couple weeks.

The sections below describe a few projects in a bit more detail. Enjoy the new release, and thanks for all the contributions,

  Gazebo Development Team

Ignition Robotics Documentation Platform

An updated documentation platform has been created for Ignition Robotics at ignitionrobotics.org. This website details the available libraries, along with a brief description for each and links to API documentation and tutorials, which are sparse at this point. A version history for each library is also displayed with links to the version's documentation.

Ignition Fuel

Around the time of the DARPA Robotics Challenge, Gazebo faced the problem of where and how to host simulation models and related assets. At the time, we opted to use a BitBucket repository (then migrated to a GitHub repository) along with a clone backed by Apache.

Gazebo has since outgrown the GitHub and Apache approach. Key problems that we have encountered are scalability, up-time, hosting meta-data, inclusion of worlds and other assets, and ease of use. After studying available options, such as using S3, we decided to provide a new simulation asset hosting service called Ignition Fuel.

Ignition Fuel is in Beta, and does not replace the existing GitHub+Apache solution. When Fuel moves out of beta, there will be an extended transition period where both hosting solutions will be active and maintained. The exact time frame will be determined when we are comfortable with the state of Fuel.

On Ignition Fuel you can find a list of available models. Logging into the site allows you to upload new models. There is also information about how to access the models programmatically through a REST API. Gazebo 9 optionally uses this API to list and download models from Fuel. In the tutorial section of Ignition Fuel Tools, you can find examples of how to manage models from a Fuel server programmatically.

The primary difference between Fuel and other asset hosting sites is that the models hosted on Fuel will contain not only visual information but also simulation information, such as links, joint, and inertia. Fuel will also move toward inclusion of worlds and potentially simulation plugins.

Ignition Transport Highlight

Gazebo makes heavy use of asynchronous message passing. For example, the Gazebo GUI operates in a separate process from the server and relies on message passing to display information and transmit user requests. Gazebo's current internal communication uses a home-grown strategy based on Protobuf and boost::asio. This has performed well but requires maintenance and has become a bit outdated.

Development of Ignition Transport provided the opportunity to choose a new strategy that would reduce our maintenance effort and offer new features. ZeroMQ has been chosen as a replacement to boost::asio, and Protobuf remains as the message definition. ZeroMQ is an open source communication library that is used across numerous domains, and has a large and active community. In addition to these aspects, ZeroMQ has a well established feature and change process, known performance, numerous language bindings, cross-platform support , and security through authentication and encryption.

In addition to the features provided by ZeroMQ, Ignition Transport provides discovery, and command line tools for topic introspection and publication of messages. Upcoming features include data logging, and integration of encryption and UDP provided in ZeroMQ. A series of benchmark tests of Ignition Transport were recently performed to evaluate the library's performance and establish a baseline. We will start with a few definitions for clarity.
  • Intraprocess: Publisher and subscriber in same process.
  • Interprocess: Publisher and subscriber in separate processes on the same physical machine.
  • Wireless: Publisher and subscriber on separate machines where one computer was connected to wireless access point and the other hardwired to the LAN.
  • Latency: Latency was measured by publishing a message on topicA, and then waiting for a response on topicB. The time between publication and reception of the response was divided in half to compute the one-way latency time.
  • Throughput: Throughput was measured by rapidly publishing N messages. Once the N messages have been published, the publisher waits for N responses. The time from start of publication to reception of all N messages is used to compute throughput.

Tests were performed on Ubuntu Xenial with the Linux 4.5.2 kernel, on a Intel i7-5930K desktop PC. The test program, called bench, is publicly available. Use the `-h` command line option with bench for usage information. Latency and throughput results are below. Click on dataset label, such as "Interprocess", to enable or disable the data.

These results can be used as one reference point, but they are by no means an exhaustive or comprehensive study of Ignition Transport.