[ros-users] ROS & DDS

Moritz Tenorth tenorth at cs.uni-bremen.de
Sun Feb 16 13:40:56 UTC 2014


simplicity of use is one thing, and from your explanations I'm positive 
that complexity can be hidden. Another thing is simplicity of migration 
-- not only a technical issue, but rather a community issue. Changing 
the core ROS transport layer means migrating several client libraries 
for C++, Python, Lisp, Java, Matlab, R, Lua, etc

On the one hand, we cannot expect the small crew at OSRF to migrate all 
libraries. On the other hand, for researchers who do not primarily work 
in robot middleware architectures and whose use cases do not require the 
new functionality, there may not be a strong incentive to invest 
significant time into migration and it may be difficult to get funding 
for this. In that case, the only alternative for some groups may be to 
stick to older versions of ROS, leading to more fragmentation of the 
community. So there should be a migration path also for other language 
libraries, and ideally a way that older software can still be used for a 

Best regards,

On 02/16/2014 09:16 AM, Christian Schlegel wrote:
> Hi,
> "freedom of choice" is what general purpose tools like CORBA etc. provide. They give no guidance which parts to use in what situation. They require far too much knowledge from standard users but provide all you need for experts (framework builder, all kinds of domains, etc., all kinds of interoperable implementations of the standards).  You never ever should expose these to the domain experts that is the robotics experts.
> "freedom from choice" is what we provide by a domain-specific presentation of those artefacts along with their proper configuration. We present communication patterns with an agreed semantics and all the mapping onto standard middleware is hidden (including which CORBA, DDS, ACE, zeroMQ etc. concepts are selected and how they are configured). Thus, the abstraction is NOT presenting everything of DDS and/or CORBA in a simplified way but in a domain-specific way: such how robotics people want to have their presentation.
> Exactly this helped us to seamlessly migrate from CORBA to ACE without exposing anything of that to the robotics user!
> Christian
> ---
> Prof. Dr. Christian Schlegel
> Prodekan, Studiendekan Master IS
> Fakultät Informatik
> Hochschule Ulm
> Tel.: 0731 / 50-28242
> http://www.hs-ulm.de/schlegel
> http://www.zafh-servicerobotik.de/
> http://www.youtube.com/user/roboticsathsulm
> http://smart-robotics.sourceforge.net/
> http://www.joser.org/
>> Am 16.02.2014 um 00:19 schrieb "Michael Zillich" <zillich at acin.tuwien.ac.at>:
>> Hi,
>> my two cents regarding this discussion come from experiences with
>> another "industry-standard" middleware, that was somewhat ... complex
>> internally and thus typically was hidden under layers of convenience
>> code: the abominable CORBA.
>> (I ended up writing my own middleware after CORBA nearly killed a project)
>> I have to admit I know nothing about DDS, so forgive me if I unjustly
>> critizise it. But reading in some of the ongoing discussions that its
>> complexity can easily be handled by some abstraction layer .. that rang
>> an alarm bell.
>> If something is too complex to use for the intended target audience of
>> developers, and thus has to be hidden behind another layer (which, trust
>> me, inevitably leads to the most hilarious bugs you can possibly
>> imagine) then it is probably the wrong technology for that application
>> area. (But there are certainly other appliction areas where this
>> middleware is the perfect choice).
>> So my personal choice is always a clear and simple solution targeted at
>> a specific application area (with specific requirements, problems, and
>> development procedures and cycles) rather than a
>> solves-all-and-everyones-problems solution developled by large committees.
>> cheers,
>> Michael
>> p.s. For those interested in the CORBA story read the enlightening
>> article by Michi Henning
>>    https://queue.acm.org/detail.cfm?id=1142044
>> who as one of the authors of "Advanced CORBA Programming with C++" is
>> probably one of the only two persons on the planet, who actually
>> understood CORBA (the other person being Steve Vinoski, the other author
>> of the book).
>> -- 
>> Dr. Michael Zillich
>> ACIN Institute of Automation and Control
>> Vienna University of Technology
>> (DVR-Number 0005886)
>> Gusshausstr 27-29/E376, 1040 Vienna, Austria
>> zillich at acin.tuwien.ac.at    http://users.acin.tuwien.ac.at/mzillich
>> Tel: +43 1 58801 376648        Fax: +43 1 58801 37698
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Dr. Moritz Tenorth     | tenorth at cs.uni-bremen.de
Universität Bremen     | Am Fallturm 1
29359 Bremen           | Germany
Tel: +49 421 218-64016 | ai.uni-bremen.de/team/moritz_tenorth

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