This presentation is an introduction to eProsima Micro XRCE-DDS, an open source wire protocol that implements the OMG DDS for eXtremly Resource Constrained Environment standard (DDS-XRCE). The aim of the DDS-XRCE protocol is to provide access to the DDS Global-Data-Space from resource-constrained devices.

1. Micro XRCE-DDS: Bringing DDS into
microcontrollers
www.eprosima.com
https://micro-xrce-dds.docs.eprosima.com/en/latest/

2. DDS: a recap
DDS: Middleware specification for
Data Distribution Service.
DDS at a glance:
● Data-centricity
● Publish-Subscribe architecture
● Global data space
● Data connectivity: many-to-many
distributed network
● QoS mechanisms
● API standard guaranteeing
interoperability among
implementations
● Dynamic Discovery

3. From DDS to DDS-XRCE
Publish-Subscribe paradigm Client-Server architecture

4. The DDS-XRCE wire protocol
DDS-XRCE: DDS for eXtremely Resource-Constrained Environment.
Clients - XRCE entities on low-resource consumption devices.
Agent - XRCE entity connected with DDS global data space. Acts on behalf of Clients in the DDS world.
Main features:
● Client-server architecture
● Request-response pattern
● Connection oriented

5. Micro XRCE-DDS
Main components:
● Micro XRCE-DDS Agent
● Micro XRCE-DDS Client
Additional components:
● Generator tool
● Serialization library
eProsima Micro XRCE-DDS: First
implementation of DDS-XRCE protocol.

6. Micro XRCE-DDS
Main components:
● Micro XRCE-DDS Agent
● Micro XRCE-DDS Client
Additional components:
● Generator tool
● Serialization library
eProsima Micro XRCE-DDS: First
implementation of DDS-XRCE protocol.

7. Supported OSes and RTOSes
RTOS: Real Time Operating System
Main Features:
● Works with an advanced algorithm for scheduling tasks within
maximum time limit.
● Apt for Real-Time applications
● POSIX-compliant interface
NuttX
FreeRTOS
Linux Windows
Zephyr

8. Client-Agent communication
Communication flow:
● Client connects to agent
(upon previous knowledge
or discovery)
● Session creation (Client
proxy instantiation)
● DDS Participant creation
● Other DDS Entities
creation

9. micro-ROS: puts ROS 2 onto
microcontrollers!
The solution for creating ROS 2 nodes
into embedded devices
Micro XRCE-DDS: the micro-ROS middleware

10. Real-Time OS
Additional
drivers, …
POSIX
Micro XRCE-DDS Client
ROS Middleware Interface (rmw)
+ Additional abstractions
micro-ROS
Agent
microcontroller
C API
rcl
C++ API
(rclcpp)
Convenience functions,
deterministic execution, …
Application
component
Application
component …
rclc:
Linux, Mac OS, Windows
DDS Implementation [Fast DDS, ..]
ROS Middleware Interface (rmw)
microprocessor
C API
rcl
C++ API
(rclcpp)
Application
component
Application
component …
Python API
(rclpy)
Apps
ROS
Client Library
ROS MW
Interface
Operating
Systems
Hardware
XRCE-DDS
DDS
Micro XRCE-DDS: the micro-ROS middleware
micro-ROS
ROS 2

11. Thank you!
Francesca Finocchiaro
eProsima - Team manager
francescafinocchiaro@eprosima.com
www.eprosima.com

12. Back-up slides

13. Micro XRCE-DDS Client
Micro XRCE-DDS Client:
C99 library. Features:
● UDP, TCP, and Serial
transport support
● Micro XRCE-DDS as a wire
protocol
● Full static memory
● Configurable profiles
● Streams: best effort &
reliable
● DDS entities can be created
by: XML, reference or binary
profiles

14. Micro XRCE-DDS Agent
Micro XRCE-DDS Agent:
C++11 application &
library. Features:
● UDP, TCP, and Serial
transport support
● Fast DDS as DDS
wire protocol
● Creates Client proxy
as DDS actor
● Configurable
● Streams: best effort &
reliable