You're reading the documentation for a development version. For the latest released version, please have a look at Galactic.

ROS 2 Humble Hawksbill (codename ‘humble’; May, 2022)

Humble Hawksbill is the eighth release of ROS 2. What follows is highlights of the important changes and features in Humble Hawksbill since the last release.

Supported Platforms

Humble Hawksbill is primarily supported on the following platforms:

Tier 1 platforms:

TBD

Tier 2 platforms:

TBD

Tier 3 platforms:

TBD

For more information about RMW implementations, compiler / interpreter versions, and system dependency versions see REP 2000.

Installation

To come.

New features in this ROS 2 release

ros_args attribute & ros_arguments parameter for nodes in launch files

It is now possible to provide ROS-specific node arguments directly, without needing to use args with a leading --ros-args flag:

<launch>
  <node pkg="demo_nodes_cpp" exec="talker" ros_args="--log-level debug" />
</launch>

The corresponding parameter for the Node action in Python launch files is ros_arguments:

from launch import LaunchDescription
import launch_ros.actions

def generate_launch_description():
    return LaunchDescription([
        launch_ros.actions.Node(
            package='demo_nodes_cpp',
            executable='talker',
            ros_arguments=['--log-level', 'debug'],
        ),
    ])

Related PRs: ros2/launch_ros#249 and ros2/launch_ros#253.

Changes since the Galactic release

common_interfaces

Support Textures and Embedded Meshes for Marker Messages

These two additions will improve the ability to both visualize data in new ways with standard messages and, simultaneously, enable the ability to track this data in rosbag.

Textures bring the addition of three new fields to markers:

# Texture resource is a special URI that can either reference a texture file in
# a format acceptable to (resource retriever)[https://index.ros.org/p/resource_retriever/]
# or an embedded texture via a string matching the format:
#   "embedded://texture_name"
string texture_resource
# An image to be loaded into the rendering engine as the texture for this marker.
# This will be used iff texture_resource is set to embedded.
sensor_msgs/CompressedImage texture
# Location of each vertex within the texture; in the range: [0.0-1.0]
UVCoordinate[] uv_coordinates

RViz will fully support texture rendering through the embedded format.

To those familiar with mesh_resource, resource_retriever should be familiar. This will allow the programmer to choose where they want to load data from, either a local file or a networked file. In the interest of being able to record all data in a rosbag, the ability to embed the texture image is included.

Meshes were modified in a similar way to add the ability to embed a raw Mesh file for the purpose of recording and are modified in a similar way. The Meshfile message has two fields:

# The filename is used for both debug purposes and to provide a file extension
# for whatever parser is used.
string filename

# This stores the raw text of the mesh file.
uint8[] data

The embedded Meshfile message is not yet supported in implementation.

Related PRs: ros2/common_interfaces#153 ros2/rviz#719

rmw

struct type name suffix changed from _t to _s

To avoid type name duplication errors between struct type names and their typedef-ed aliases when generating code documentation, the suffix for all struct type names has been changed from _t to _s. Aliases with _t suffixes remain in place. Thus, this change is a breaking change only for code that uses full struct type specifiers i.e. struct type_name_t.

See ros2/rmw#313 for more details.

rcl

struct type name suffix changed from _t to _s

To avoid type name duplication errors between struct type names and their typedef-ed aliases when generating code documentation, the suffix for all struct type names has been changed from _t to _s. Aliases with _t suffixes remain in place. Thus, this change is a breaking change only for code that uses full struct type specifiers i.e. struct type_name_t.

See ros2/rcl#932 for more details.

rclcpp

Support Type Adaption for Publishers and Subscriptions

After defining a type adapter, custom data structures can be used directly by publishers and subscribers, which helps to avoid additional work for the programmer and potential sources of errors. This is especially useful when working with complex data types, such as when converting OpenCV’s cv::Map to ROS’s sensor_msgs/msg/Image type.

Here is an example of a type adapter that converts std_msgs::msg::String to std::string:

template<>
struct rclcpp::TypeAdapter<
   std::string,
   std_msgs::msg::String
>
{
  using is_specialized = std::true_type;
  using custom_type = std::string;
  using ros_message_type = std_msgs::msg::String;

  static
  void
  convert_to_ros_message(
    const custom_type & source,
    ros_message_type & destination)
  {
    destination.data = source;
  }

  static
  void
  convert_to_custom(
    const ros_message_type & source,
    custom_type & destination)
  {
    destination = source.data;
  }
};

And an example of how the type adapter can be used:

using MyAdaptedType = TypeAdapter<std::string, std_msgs::msg::String>;

// Publish a std::string
auto pub = node->create_publisher<MyAdaptedType>(...);
std::string custom_msg = "My std::string"
pub->publish(custom_msg);

// Pass a std::string to a subscription's callback
auto sub = node->create_subscription<MyAdaptedType>(
  "topic",
  10,
  [](const std::string & msg) {...});

To learn more, see the publisher and subscription) examples, as well as a more complex demo. For more details, see REP 2007.

get_callback_groups method removed from NodeBase and Node classes

for_each_callback_group() method has replaced get_callback_groups() by providing a thread-safe way to access callback_groups_ vector. for_each_callback_group() accepts a function as an argument, iterates over the stored callback groups, and calls the passed function to ones that are valid.

For more details, please refer to this pull request.

ros2cli

ros2 topic pub will wait for one matching subscription when using --times/--once/-1

When using --times/--once/-1 flags, ros2 topic pub will wait for one matching subscription to be found before starting to publish. This avoids the issue of the ros2cli node starting to publish before discovering a matching subscription, which results in some of the first messages being lost. This is particularly unexpected when using a reliable qos profile.

The number of matching subscriptions to wait before starting publishing can be configured with the -w/--wait-matching-subscriptions flags, e.g.:

ros2 topic pub -1 -w 3 /chatter std_msgs/msg/String "{data: 'foo'}"

to wait for three matching subscriptions before starting to publish.

-w can also be used independently of --times/--once/-1 but it only defaults to one when combined with them, otherwise the -w default is zero.

See https://github.com/ros2/ros2cli/pull/642 for more details.

ros2 param dump default output changed

  • --print option for dump command was deprecated.

    It prints to stdout by default:

    ros2 param dump /my_node_name
    
  • --output-dir option for dump command was deprecated.

    To dump parameters to a file, run:

    ros2 param dump /my_node_name > my_node_name.yaml
    

robot_state_publisher

Removal of deprecated use_tf_static parameter

The deprecated use_tf_static parameter has been removed from robot_state_publisher. This means that static transforms are unconditionally published to the /tf_static topic, and that the static transforms are published in a transient_local Quality of Service. This was the default behavior, and the behavior which the tf2_ros::TransformListener class expected before, so most code will not have to be changed. Any code that was relying on robot_state_publisher to periodically publish static transforms to /tf will have to be updated to subscribe to /tf_static as a transient_local subscription instead.

rosidl_cmake

Deprecation of rosidl_target_interfaces()

The CMake function rosidl_target_interfaces() has been deprecated, and now issues a CMake warning when called. Users wanting to use messages/services/actions in the same ROS package that generated them should instead call rosidl_get_typesupport_target() and then target_link_libraries() to make their targets depend on the returned typesupport target. See https://github.com/ros2/rosidl/pull/606 for more details, and https://github.com/ros2/demos/pull/529 for an example of using the new function.

geometry2

Deprecation of TF2Error::NO_ERROR, etc

The tf2 library uses an enumeration called TF2Error to return errors. Unfortunately, one of the enumerators in there is called NO_ERROR, which conflicts with a macro on Windows. To remedy this, a new set of enumerators in TF2Error were created, each with a TF2 prefix. The previous enumerators are still available, but are now deprecated and will print a deprecation warning if used. All code that uses the TF2Error enumerator should be updated to use the new TF2 prefixed errors. See https://github.com/ros2/geometry2/pull/349 for more details.

Known Issues

To come.

Release Timeline

Mon. March 21, 2022 - Alpha + RMW freeze

Preliminary testing and stabilization of ROS Base 1 packages, and API and feature freeze for RMW provider packages.

Mon. April 4, 2022 - Freeze

API and feature freeze for ROS Base 1 packages in Rolling Ridley. Only bug fix releases should be made after this point. New packages can be released independently.

Mon. April 18, 2022 - Branch

Branch from Rolling Ridley. rosdistro is reopened for Rolling PRs for ROS Base 1 packages. Humble development shifts from ros-rolling-* packages to ros-humble-* packages.

Mon. April 25, 2022 - Beta

Updated releases of ROS Desktop 2 packages available. Call for general testing.

Mon. May 16, 2022 - Release Candidate

Release Candidate packages are built. Updated releases of ROS Desktop 2 packages available.

Thu. May 19, 2022 - Distro Freeze

Freeze rosdistro. No PRs for Humble on the rosdistro repo will be merged (reopens after the release announcement).

Mon. May 23, 2022 - General Availability

Release announcement. rosdistro is reopened for Humble PRs.

1(1,2,3)

The ros_base variant is described in REP 2001 (ros-base).

2(1,2)

The desktop variant is described in REP 2001 (desktop-variants).