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Interfacing a native DDS system with ROS2?

asked 2018-07-25 11:21:14 -0500

aks gravatar image

updated 2018-07-26 03:52:30 -0500

I want to interface RTI connext with ROS2.

Use Case : I run a talker_py in ROS2 which has a default qos and subscribe to these messages in RTI Connext. How do I modify the QoS/XmL in RTI to be ROS2 compatible ?

Using qos_profile = rmw_qos_profile_system_default will use the default xml configuration from the installation directory of the DDS vendor, RTI CONNEXT in this case. Is it correct ?

Looking at this documentation from RTI, it means that the file NDDS_QOS_PROFILES.xml is loaded. But this file doesnt have any QoS settings.

Also, the way ROS2 generated idl's is a bit ROS2 specific e.g. package::message::dds_::message_name and I guess the XML/ IDL in the DDS needs to be adapted to the one used by ROS2 ? Am I correct ?

A bit confused about this workflow. kindly help.

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answered 2018-07-26 05:50:34 -0500

updated 2018-07-26 05:57:37 -0500

Hello,

I did a similar setup for RTI Connext Micro. It should follow the same steps:

You need to configure the same partition name ( https://community.rti.com/static/docu... ). Which should be set in the QoS.

You need to update the .idl to have the same fields as in your messages in ROS2. The types are almost identical (uint32 versus uint32_t... for CPP).

Once you have generated the code:

GENERATOR=$(BASE)/rtiddsgen/scripts/rtiddsgen -language C++ $(IDL_PREFIX).idl

You can update the QoS by creating your own profile https://community.rti.com/examples/us... You will have to register the correct topic name using the function create_topic (the parameter you gave once you created the node:

publisher_ = this->create_publisher<std_msgs::msg::String>("topic");

In this case "topic")

And update the type_name. In my case I was using the typename "std_msgs::msg::dds_::String_" as I was using https://github.com/ros2/common_interf... (register_type function) You can have a look at the mangled name in the RWM package of Connext.

If you want to get the typename, topic, QoS, you can use the tools provided by RTI Launcher.

As I was working on RTI Connext Micro, those steps are probably different (hopefully similar) but maybe it can help you.

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Thankyou for the explanataion : Few things :

  1. since ros2 bouncy bolson, no partitions are being used (everything is in the same partition), so no need to configue it.
  2. Already modified the XML according to ROS2 idl definition.
  3. How can I define the exact QoS as in ROS2 default QoS ? Stuck!
aks gravatar imageaks ( 2018-07-26 06:56:14 -0500 )edit

Ah! Sorry my setup has been done for ardent. I should have mentioned that.

pokitoz gravatar imagepokitoz ( 2018-07-26 07:34:32 -0500 )edit

Were you successful in parsing the module keyword. As the ROS2 generated IDL files have module and when I add it to the XML file used by RTI, it is unable to parse it.

aks gravatar imageaks ( 2018-07-26 09:20:00 -0500 )edit

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Asked: 2018-07-25 11:21:14 -0500

Seen: 245 times

Last updated: Jul 26 '18