Scaling Down: DDS into Sensor Networks Reply

london connext conference rti EMEA 2014

Connext Conference 2014 is taking place 8-9 October in London. To learn more or RSVP, visit

Below is an abstract of a talk that RTI plans to have available at the RTI Connext Users Group meeting, to be held in London next week (

RTI is a firm believer in the Data Centric model of Pub/Sub. Even in places we can’t yet reach.

When it’s a question of scale, customers of RTI generally ask about the macro abilities of Connext DDS: how far up, or how far out RTI Connext DDS will scale, looking to support thousands, tens of thousands or even millions of discrete points-of-presence across their systems of systems. Sometimes this happens at design time, sometimes this happens after deployment.

On the other hand, sometimes it’s scaling downwards. RTI Connext Micro and Connext Cert support applications running on devices with limited size, weight and power requirements, but these systems still assume a certain level of hardware and capability.

Yet, there is still room for more — or in this case, less!

RheinMain University ( in Wiesbaden, Germany, has spent years looking at using the OMG DDS standard in the sub-RTI Micro domain. Here is Kai Beckmann, Dipl.-Inform.(FH), M.Sc., discussing what they’ve been working on.

sDDS – An adaptable DDS Solution for Wireless Sensor Networks.

Wireless Sensor Networks (WSN, cf. ZigBee, 6LoWPAN) are maturing into real world applications, from classical environment monitoring, home automation and the internet of things to industrial automation scenarios. There are improvements regarding available hardware resources, but the energy consumption is yet a limiting factor, and so are the heterogeneous software and hardware platforms. The Data Distribution Service (DDS) provides a standardised interoperable data-centric publish/subscribe architecture with real-time capabilities, suitable for many data-centric WSN scenarios.

However, DDS is rooted in larger-scale architectures – the full middleware functionality generally exceeds the available resources on an average sensor node – and the RTPS network protocol is not tailored to the small network frames common to WSN. We therefore propose sDDS, a DDS implementation for minimal embedded systems found in WSN. A Model-driven software development (MDSD) process is utilised to specify the system structure and applications requirements of the DDS functionality, and to generate individual sDDS implementations for each node. Furthermore, we present SNPS as an alternative transport protocol for DDS communication, particularly in WSN scenarios. SNPS has been designed as part of sDDS, optimizing for minimal footprint and compatibility between sDDS instances with different subsets of functionality.

Longer term, I would like to work with RheinMain University, with the purpose of bridging their SNPS transport protocol into an RTPS-based, full RTI Connext DDS system — giving the full scale system direct, data-centric access to the WSN for the purposes of aggregation, C2 and HMI, and giving the WSN direct, data-centric access to full scale systems for off-node processing.

If the idea of data-centric Sensor Networks interest you, there’s still time to register to attend.

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