ROS1_bridge: How to map multiple messages and variables with custom datatypes between ROS1- ROS2 using mapping rule yaml file?

asked 2018-09-07 07:25:27 -0600

Rucha
13 ●2 ●2 ●5

updated 2018-09-11 05:44:13 -0600

If there are multiple messages from one ros1 package are to be mapped to multiple messages from one ros2 package, how it should be done using yaml file? I need such mapping in following use-cases:

1) Suppose ros1 package has messages like A.msg, B.msg and ROS2 package has messages like X.msg, Y.msg and I want to map variables of messages as A <-> X, B<->Y. So I tried the mapping in YAML file as: I

 ros1_package_name: 'ros1_test'
 ros1_message_name: 'A'
 ros2_package_name: 'ros2_test'
 ros2_message_name: 'X' 

 fields_1_to_2:
  a_var: 'x_var'

 ros1_package_name: 'ros1_test'
 ros1_message_name: 'B'
 ros2_package_name: 'ros2_test'
 ros2_message_name: 'Y' 

 fields_1_to_2:
  b_var: 'y_var'

If this mapping is used, ROS1 bridge only maps B<->Y. The A<->X mapping is not done; Probably because it is overwritten. So how exactly such multiple message mapping should be done?

2) In this scenario, the problem is with mapping variables of custom datatype consider that A.msg is a message in ROS1 package. X.msg, Y.msg are the messages in ROS2 package; which are as follows:

A. msg (ROS1 message)

int32 a_var

X.msg (ROS2 message)

Y x_var

Y.msg (ROS2 message)

int32 y1
float32 y2
int32 y3

In this case, how to map A.msg <->X.msg and variables a_var <-> x_var.y1 using mapping rules in yaml file?

Looking forward to suggestions and answers.

answered 2018-09-07 10:15:31 -0600

Dirk Thomas
16276 ●62 ●190 ●215

Your YAML snippet looks incorrect. See the documentation for an example:

-
  ros1_package_name: 'ros1_pkg_name'
  ros1_message_name: 'ros1_msg_name'
  ros2_package_name: 'ros2_pkg_name'
  ros2_message_name: 'ros2_msg_name'
  fields_1_to_2:
    foo: 'foo'
    ros1_bar: 'ros2_bar'

Note the dash (-) in the very first line which makes all the following key-values a first item in a list. In order to enumerate multiple entries each of them must have that leading line with that dash (indicating a separate item in the list):

-
  ros1_package_name: 'ros1_pkgA_name'
  ros1_message_name: 'ros1_msgA_name'
  ros2_package_name: 'ros2_pkgA_name'
  ros2_message_name: 'ros2_msgA_name'
  fields_1_to_2:
    foo: 'foo'
    ros1_bar: 'ros2_bar'
-
  ros1_package_name: 'ros1_pkgB_name'
  ros1_message_name: 'ros1_msgB_name'
  ros2_package_name: 'ros2_pkgB_name'
  ros2_message_name: 'ros2_msgB_name'
  fields_1_to_2:
    foo: 'foo'
    ros1_bar: 'ros2_bar'

edit flag offensive delete link

Comments

Thank you for the answer of scenario 1. I had put '-' as a first line of file but forgot to paste in code snippet of question; However, I did not put '-' before next mapping, so it was not working. Now I added it, and works fine. Could you please suggest solution for scenario 2 ? It is not solved.

Rucha ( 2018-09-11 05:25:12 -0600 )edit

I guess you have tried a_var <-> x_var.y1 and it didn't work? To support this use case the logic in the ros1_bridge would need to be extended. Please consider to provide a pull request for this use case.

Dirk Thomas ( 2018-09-11 11:11:15 -0600 )edit

Yes, I had tried this mapping, but it didn't work. I will have to use this use-case multiple times in my work, so it would be good if such mapping is supported by ros1_bridge.

Rucha ( 2018-09-12 07:57:44 -0600 )edit

I will try to extend ros1_bridge to support such mapping. Since I am new to this, I wanted to know exactly which code segment needs to be focused for field mapping in ros1_bridge and some starting point to implement this functionality.

Rucha ( 2018-09-12 08:12:46 -0600 )edit

The rule parsing happens in the Python module ros1_bridge/__init__.py:336 and at some point generates the C++ code which is performing the actual mapping in this template: resource/pkg_factories.cpp.em.

Dirk Thomas ( 2018-09-12 10:45:18 -0600 )edit

this point about a dash needing to separate mapped pairs should really be in the tutorial i.e. https://github.com/ros2/ros1_bridge/b...

blarghflargle ( 2020-08-17 23:47:26 -0600 )edit

@blarghflargle The dash is part of the example snippets already. This is just YAML and for a list of items each item is identified by a dash. Please consider to contribute a pull request to the documentation if you want to propose any improvements,

Dirk Thomas ( 2020-08-18 00:14:31 -0600 )edit

add a comment

ROS1_bridge: How to map multiple messages and variables with custom datatypes between ROS1- ROS2 using mapping rule yaml file?

1 Answer

Comments

Question Tools

Stats

Related questions

ROS1_bridge: How to map multiple messages and variables with custom datatypes between ROS1- ROS2 using mapping rule yaml file? edit

1 Answer

Comments

Question Tools

Stats

Related questions

ROS1_bridge: How to map multiple messages and variables with custom datatypes between ROS1- ROS2 using mapping rule yaml file?