The Proposal

December 8, 2017

Dear all,

I wanted to share with the ROS community the proposal we made yesterday afternoon to other DDS vendors, the OMG MARS Taskforce and the XRCE evaluation team on a possible way forward.

Before articulating the proposal let me give some context.

As a result of the XRCE standardisation process we need to select one of the proposals (our proposal is available here). On the ROS mailing list we have discussed few aspects of the protocol and @gbiggs provides here above a good and independent analysis on the two proposals with Erik and myself clarifying a few points here and here respectively. Thus if you have not read those I suggest you do before continuing reading things.

With reference to @gbiggs analysis, we have one proposal (ours) that is perceived as being slightly more complex but that supports peer-to-peer as well as client-to-broker and is more suited for constrained environments. The other (RTIandCo) which appears to be simpler but only supports client-to-broker and carries more overhead.

If along with this information, we take into account that we (ADLINK):

  1. have made available our XRCE implementation as Open Source under Apache 2 as part of the project, and

  2. are going to release a C++ broker by the end of the year (we already have a Swift and a Scala broker implemented – some folks have seen these in actions at various demonstrations), and

  3. are committed to make the XRCE reference implementation, both in terms of standards as well as quality

Now that the context is given I can enunciate the proposal I made to other vendors, task force & co:

Adopt our proposal and join forces, around the newly established open source project (zenoh), to accelerate the establishment of the XRCE standard in constrained environments.

The advantages of my proposal are several:

  1. End-users such as the ROS community would get access to an implementation of the standard much more quickly – essentially now.

  2. Other DDS vendors could have immediately constrained connectivity by simply integrating their DDS implementation on the broker.

  3. We would have an open source implementation of XRCE supported by all DDS vendors, which means no interoperability issues, faster evolution, and faster adoption.

  4. We would have a protocol that can do peer-to-peer as well as brokered communication, which is good for some use cases – most notably in robotics.

  5. We would have a protocol that could be deployed down to the sensors. Imagine for a moment having ROS-enabled sensors talking XRCE via low-power protocols or anything else that suits them.

  6. As the one protocol everyone uses and supports is open-source we would facilitate adoption immensely.

Collaboration can bring us much more further away than competition. What has made humans excel is our ability to collaborate not so much that to compete… Thus, why not in this case?

I am looking forward to hear comments from the ROS community. Please speak-up.

– Angelo Corsaro

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