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  Beta3-Overview

Beta 3 (``r2b3``)
=================

.. contents:: Table of Contents
   :depth: 2
   :local:

Supported Platforms
-------------------

We support ROS 2 Beta 3 on three platforms: Ubuntu 16.04 (Xenial), macOS 10.12 (Sierra), and Windows 10.
We provide both binary packages and instructions for how to compile from source for all 3 platforms (see `install instructions <../../Installation>` as well as `documentation <https://docs.ros2.org/beta3/>`__).

Features
--------

Improvements since Beta 2 release
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* Execution model in Python, many fixes to memory management in Python C extension
* Experimental rewrite of `ros_control <https://github.com/ros2/ros2_control>`__
* Exposure of DDS implementation-specific symbols to users (for Fast RTPS and Connext) (see `example <https://github.com/ros2/demos/blob/6363be2efe2fea799d92bc22a66e776b2ca9c5d0/demo_nodes_cpp_native/src/talker.cpp>`__)
* Logging `API <https://github.com/ros2/rclpy/blob/1ef2924ef8e154c0553edf0fdba4840b08b728f8/rclpy/rclpy/logging.py>`__ in Python
* Fixed several memory leaks and race conditions in various packages
* Readded support for OpenSplice (on Linux and Windows atm) provided by PrismTech
* Use bloom (without patches) to make ROS 2 releases

New demo application
^^^^^^^^^^^^^^^^^^^^

* `HSR demo <https://github.com/ruffsl/hsr_demo>`__

  * Remote control a HSR robot using a ROS 2 joystick controller
  * Running the ``ros1_bridge`` in a Docker container on the HSR (since the robot is running ROS 1 on Ubuntu Trusty)
  * Run a ROS 2 development version of `rviz <https://github.com/ros2/rviz>`__ to visualize sensor data from the robot etc. (see `video <https://vimeo.com/237016358>`__)

Selected features from previous Alpha/Beta releases
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

For the complete list, see `earlier release notes <../index>`.

* C++ and Python implementations of ROS 2 client libraries including APIs for:

  * Publishing and subscribing to ROS topics
  * Requesting and replying ROS services (synchronous (C++ only) and asynchronous)
  * Getting and setting ROS parameters (C++ only, synchronous and asynchronous)
  * Timer callbacks

* Support for interoperability between multiple DDS/RTPS implementations

  * eProsima Fast RTPS is our default implementation, and is included in the binary packages
  * RTI Connext is supported: build from source to try it out
  * PrismTech OpenSplice: see limitations below

* A graph API for network events
* Distributed discovery
* Realtime safe code paths for publish and subscribe with compatible DDS implementation (only Connext at the moment)

  * Support for custom allocators

* ROS 1 <-> ROS 2 dynamic bridge node
* Executor threading model (C++ and Python)
* Component model to compose nodes at compile / link / runtime
* Managed component using a standard lifecycle
* Extended ``.msg`` format with new features:

  * Bounded arrays
  * Default values

Known issues
------------

* On Windows Python launch files might hang when trying to abort using ``Ctrl-C`` (see `issue <https://github.com/ros2/launch/issues/64>`__). In order to continue using the shell which is blocked by the hanging command you might want to end the hanging Python process using the process monitor.
* OpenSplice support is currently not available for MacOS. Also `access to native handles <https://github.com/ros2/rmw_opensplice/issues/182>`__ is not yet implemented.
* Using Connext it is currently not allowed for two topics with the same base name but different namespaces to have a different type (see `issue <https://github.com/ros2/rmw_connext/issues/234>`__).