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From Otto Fowler <>
Subject Re: [DISCUSS] The State and Future of PLC4X
Date Fri, 19 Apr 2019 12:27:50 GMT
RFC 62541?

On April 18, 2019 at 05:38:56, Christofer Dutz (

Perfect ;-)

Am 18.04.19, 11:34 schrieb "Julian Feinauer" <>:

Hi Chris,

So lets simply use the terms opc-ua server or bridge and opc-ua client : )
Do you agree?


Am 18.04.19, 11:32 schrieb "Christofer Dutz" <>:

Hi Julian,

That's what I mentioned in the other email.
We have to be careful with the term OPC-UA Support and differentiate
between OPC-UA Server and OPC-UA Client (PLC4X opc-ua client)
I was talking about a OPC-UA Server ... you seem to be about a client. For
the Server we wouldn't need the feature you are mentioning.


Am 18.04.19, 11:27 schrieb "Julian Feinauer" <>:

Hi Chris,

there are two ways.. and you are doing the other one, I think : )
You are talking about the OPC UA interface for other drivers, or?
There, you do that implicitly by your config, so this is fine.

But, especially when we start to implement an OPC UA Driver, this will fall
on our feet : )


Am 18.04.19, 11:19 schrieb "Christofer Dutz" <>:

Hi Julian

I don't agree that we have to do the other first.
Right now I was thinking about building a configuration that could offer a
complex type structure to OPC-UA clients but map simple Addresses to
elements of such a tree.
So I think we could start without refactoring.


Am 18.04.19, 09:15 schrieb "Julian Feinauer" <>:

Hi Markus,

I agree with you.
And, as one can see in my mail.. there are multple efforts which are
currently going.
So perhaps, if we focus a bit, we should reach first results pretty fast.
But I think one necessity is a refactoring to a complex type model.
I will file a Jira for that.


Am 18.04.19, 09:06 schrieb "Markus Sommer" <>:

Hi all,

I was at the Hannovermesse and the industry clearly relies on OPC UA. If
PLC4x could realize a very fast OPC UA, this would be a massive advantage
over other manufacturers.

Best regards


Freundliche Grüße

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-----Ursprüngliche Nachricht-----
Von: Julian Feinauer <>
Gesendet: Mittwoch, 17. April 2019 09:07
Betreff: [DISCUSS] The State and Future of PLC4X

Hi all,

as we had a lot of non-technical discussions and topics the last time (the
coming of age of a software project, I guess) it’s time for us to go back
to the real fun part and do technical shit.
I had a lot of discussions (on list and off list) with several people like
Chris, Matthias, Björn, Tim and others and wanted to share my thoughts on
the future of PLC4X as I see it (from a solely technical perspective).

Currently, I see several “fronts” or centers of activity (or where I think
we should spend it).

* Language adoption – We should define and deliver APIs and bindings for
other languages to bring what we currently have to other people and other
communities. The activities we have there are currently (from my head):
Markus and C++, Björn who wanted to investigate C# and the “Interop Server”
which I played around a bit (in fact, Matthias made a python binding
* Driver Generation – This is a well-known Topic which is currently driven
by Chris. This is a large topic, which includes
* Model Generation (currently dfdl and state-xml)
* Templates for many languages (will partially derive from above)
* A build process, to wire both together
* Some kind of Test Suite to check the correct generation of drivers
* Automated Documentation / Spec Generation (!!
* Ecosystem / Tools – We have a set of tools that are based on PLC4X and
which enable to do things which where unthinkable before. Some are
* Scraper – A tool to scrape massive amounts of data from multiple PLCs
based on a yml configuration, this is mostly driven by Tim
* OPC UA Server – Yet to come. Maps OPC UA requests to PLC4X requests which
then go native to the PLCs. Matthias started some work on this, Tim looked
over it and I think Chris plans on implementing something here also
* We had multiple discussions about tools that “guess” something about
locations of variables or their types. Chris brought that up yesterday and
plans to do something there, Matthias and I discussed this several times
and we plan to also do something with one or two students there
* New programming models – As plc4x is open, it allows us to implement new
programming models on top of it. The best example I can give is OPM, the
JPA equivalent of PLC4X. The idea is to work with POJOs and annotations and
EntityManagers (as Beans) and have a “type safe” and Business-esque way to
communicate with PLCs.

Here I see a lot of potential and possible next steps could be (discussed
by Matthias and me)

* “Richer” Typesystem (not just primitives and Arrays as currently) which
covers complex objects
* Mapping of complex objects from POJOs to PLC segments (Like structs in S7
or ADS)
* Auto-generation of annotated POJOs from PLC programs (much like JPA or
the C# ORM does that based on an existing database). This could be a
“killer-feature” as it would really allow type-safe end to end
communication with the plc with zero plc specific knowledge

Other Topics in this area that can be named are

* A connection pool to share / reuse connections for efficiency (which was
implemented by Sebastian and is absolutely crucial for us!)
* A central monitoring component (similar to how a Webserver monitors each
side access and the results and latencies and so..), I am currently working
on this and hope to provide a PR soon

Of course, all of this is solely based on my personal opinion or things
that came out in discussions with other involved people.
For me, this structure makes sense and perhaps it helps us to “broaden” our
scope a bit from the initial focus (drivers, drivers, drivers) to the new
picture which evolved over the last to years.

Of course, feel free to agree, disagree or participate with other opinions.


PS.: I could offer to bring this in a more “presentable” form and prepare a
short “overview” talk about this for the next meetup, if interesting

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