Choosing DDS/RTPS Implementation

[Advanced]

There are many factors you might consider while choosing a middleware implementation: logistical considerations like the license, or technical considerations like platform availability, or computation footprint.

Vendors may provide more than one DDS or RTPS implementation targeted at meeting different needs.

Supported DDS Implementations and RMWs

Vendor	License	RMW Package	Status
eProsima Fast DDS	Apache 2	rmw_fastrtps_cpp	Full support (default)
Eclipse Cyclone DDS	EPL v2.0	rmw_cyclonedds_cpp	Full support
RTI Connext DDS	Commercial/Research	rmw_connextdds	Full support (needs install)
GurumNetworks GurumDDS	Commercial	rmw_gurumdds_cpp	Community support

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Using Multiple RMW Implementations

• ROS 2 binaries include support for several RMWs by default.

• Fast DDS is the default.

• You can switch to other RMWs without rebuilding ROS 2, just by setting environment variables.

• If building from source, multiple RMWs can be built at once if dependencies are available.

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Cross-Vendor Compatibility Notes

• Not all DDS implementations can talk to each other reliably.

• Known issues:

  • Fast DDS ↔ Connext: WString issue on macOS

  • Connext ↔ Cyclone DDS: WString communication not supported

• Best practice: Use the same RMW across your entire system.

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Default RMW Selection

• If rmw_fastrtps_cpp is installed, it’s used by default.

• Otherwise, the default is the alphabetically first installed RMW package.