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ROS2 conversion of .msg files into .idl files

asked 2018-06-04 04:44:29 -0500

aks gravatar image

updated 2018-06-04 04:57:52 -0500

tfoote gravatar image

I have currently a faint understanding of the ROS2 system. I read that in ROS2 the msg files are converted into idl files before publishing and then these idl files are used for publishing and subscribing. In this image, how can i understand the circled part, ROS to DDS conversion functions...shouldnt there be an arrow as shown ? e.g. with help of these conversion functions, idl files are generated from msg files ?

conversion

I need to somehow access these idl or msg files and perform read and write operations ? Is there a possibility that i can do that ? Are there some examples ?

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answered 2018-07-05 17:48:18 -0500

Dirk Thomas gravatar image

The diagram only indicates how the information flows. The conversion functions mapping ROS messages to DDS messages are being generated for each DDS implementation (using their native vendor-specific DDS types). As input these templates only need the message definitions - it doesn't need any information from the .idl files - since those are generated from the message definitions themselves they don't contain any more information.

For the generated source code there is a dependency from the conversion functions on the DDS message classes as they are in e.g. C++ being included.

I am not sure what "read and write operations" you are intending to do. You will find the .idl files after building a package under <install>/share/<pkgname>/msg|srv/dds_connext|dds_opensplice. They are being generated and installed by the rosidl_generator_dds_idl package.

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Asked: 2018-06-04 04:44:29 -0500

Seen: 250 times

Last updated: Jul 05 '18