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From Julian Feinauer <j.feina...@pragmaticminds.de>
Subject Re: Antwort: Re: Antwort: Re: Antwort: Re: Antwort: Re: Anyone got experience with "protocol buffers" or DFDL (for generation of the message (de)serialization code)?
Date Tue, 15 Jan 2019 09:33:04 GMT
Hi Chris,

thank you so much for your effort.
I think this ist he right way to go forward and get more languages on-board.
Hopefully, we can gather some interest in the Daffodil community that it doesn't all last
on your shoulders (as I'm not capable of helping out currently).

But perhaps also someone else from the list has an interest to jump in? : )

Best
Julian

Am 15.01.19, 10:24 schrieb "Christofer Dutz" <christofer.dutz@c-ware.de>:

    Hi all,
    
    just some feedback on my efforts towards formal definition of protocol message types:
    
    It seems that DFDL is a perfect match for defining the data formats.
    Right now I'm working hard on writing a DFDL schema for the S7 Protocol as this has quite
a number of "specialities" that provide a challenge when writing such a definition.
    As soon as that's finished I guess we know if this is the way to go. 
    
    Unfortunately this is where the real work begins. As Daffodil (The Apache implementation
of a DFDL framework ... the other one is from IBM but not so feature-rich) parses any data
using DFDL schemas into a JSON or XML presentation.
    What it currently doesn't do is parse into a generic model and/or generate code. 
    
    This is where I will probably have to invest some time in the Apache Daffodil Incubator
podling and help them implement the missing parts. 
    I know this is quite some work, but it will be a HUGE benefit for our project and it will
also help our brother project greatly.
    
    What will be possible with Daffodil, is that we can replace the "pcapng" binary captures
with XML (or JSON) versions which Daffodil can already serialize to binary data for tests
... So we get human readable test-case input.
    We can dump incoming packets into a human readable form and eventually (automatically)
generate test-case input for inspecting IO problems.
    Also could we implement a low-performance version of new protocols, by using the existing
Daffodil parsers/serializers to process a protocol specification to and from XML/JSON ...
this should be a huge benefit for new-protocol-implementors.
    As soon as a protocol is roughly implemented, we can switch to generated model, (de)serializers.
    
    So far the update and a little excuse for my silence ;-)
    
    Chris
    
    
    Am 10.01.19, 10:41 schrieb "Christofer Dutz" <christofer.dutz@c-ware.de>:
    
        Hi Markus,
        
        that is not quite true.
        
        In some cases definitely yes, but I'm currently looking into the option of using DFDL
(Apache Daffodil) for this.
        The way I would like to do it, would be to use DFDL to describe the format and then
generate code from that with a general purpose generator for which we can provide the code-generation
templates.
        This way we would have to write these templates once and exactly for PLC4X and then
have all protocols generated to perfectly fit. 
        
        Right now I am not doing anything different ... I'm trying to refactor things in a
way that is as generic as possible without any performance drawbacks and then to adjust one
protocol after the other to match that.
        
        I would like to automate this. 
        
        So as soon as a new language should be supported, someone would setup the general
skeleton driver, write a prototype and then convert that into templates and "presto" we get
all the layers generated.
        
        At least that's what I'm currently thinking of.
        
        Chris
        
        
        
        Am 10.01.19, 10:33 schrieb "Markus Sommer" <sommer@isb-fn.de>:
        
            Hello everyone,
            
            If we go the way of automatic object generation for messages, then we will have
to live with performance degradation.
            
            Best regards
            
            Markus
            
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            -----Ursprüngliche Nachricht-----
            Von: Christofer Dutz <christofer.dutz@c-ware.de> 
            Gesendet: Mittwoch, 9. Januar 2019 18:59
            An: dev@plc4x.apache.org
            Betreff: Re: Antwort: Re: Antwort: Re: Antwort: Re: Antwort: Re: Anyone got experience
with "protocol buffers" or DFDL (for generation of the message (de)serialization code)?
            
            Well I thought that went could use what's already there as I was expecting us
but to be the first. But I haven't found an option that works.
            
            Of course whipping up a coffee generator is quite simple (done it loads of times)
but you have to come up with the serialisation for all supported languages ourself. I wanted
to avoid that, cause it's a lot of work.
            
            I think we should do a little more evaluating. If we don't find anything well
go down that path.
            
            But having plugins used in a build that are also part of the build itself introduces
more issues. So perhaps becoming involved in the daffodil project and adding a code generator
there is the better option. (Code generator in Daffodil and generation templates here)
            
            Chris
            
            Outlook for Android<https://aka.ms/ghei36> herunterladen
            
            ________________________________
            From: Julian Feinauer <j.feinauer@pragmaticminds.de>
            Sent: Wednesday, January 9, 2019 6:46:14 PM
            To: dev@plc4x.apache.org
            Subject: Re: Antwort: Re: Antwort: Re: Antwort: Re: Antwort: Re: Anyone got experience
with "protocol buffers" or DFDL (for generation of the message (de)serialization code)?
            
            Okay, I see...
            When I learned something, that tooling is really important, and it makes me a
bit of sorrows that DFDL is not there yet.
            Do I take things too simple if we would just starting using something like json
(or xml, as I think chris likes xml better) to define these messages and then implement a
(very simple) converter to the class format?
            Shouldn’t this be doable?
            
            Of course there's still the lack of a Maven Plugin but I think this could be made
easily (????) if its just invocing a method (or we do something like ant task voodoo to invoke
it via CMD).
            But at least we would have nice syntax highlighting and such stuff and could rely
on Jackson to get the files to a Java Input (and in case of xml we could also do validation
directly and generate nice HTML documentatsions via xlst).
            
            Am I missing something or take things too simple?
            
            Best
            Julian
            
            Am 09.01.19, 18:26 schrieb "Christofer Dutz" <christofer.dutz@c-ware.de>:
            
                Hi Julian,
            
                Yes exactly ... Unfortunately the messages are composed of different types
of structures. Header, parameters of different type and length, payloads of different type.
But in general, yes
            
                Chris
            
                Outlook for Android<https://aka.ms/ghei36> herunterladen
            
                ________________________________
                From: Julian Feinauer <j.feinauer@pragmaticminds.de>
                Sent: Wednesday, January 9, 2019 6:16:01 PM
                To: dev@plc4x.apache.org
                Subject: Re: Antwort: Re: Antwort: Re: Antwort: Re: Antwort: Re: Anyone got
experience with "protocol buffers" or DFDL (for generation of the message (de)serialization
code)?
            
                Hi Chris,
            
                I'm not sure if I got it right, but what we would need is a way to generate
classes in multiple languages based on a message definition, or?
                So we say something like
                Bit, byte, byte, bit
                And it generates a class (or struct?) which deserializes / serializes to that,
or?
            
                Sorry for that (probably) dump question but I got a bit confused by this protobuf
/ thrift approach.
            
                Julian
            
                Am 09.01.19, 17:49 schrieb "Christofer Dutz" <christofer.dutz@c-ware.de>:
            
                    Hi Sebastian,
            
                    Well in general the difference between a read and a write in S7 is one
byte value ;-)
                    The overall structure is somewhat identical.
            
                    Chris
            
            
            
                    Von: Sebastian Wiendl <SWiendl@bhs-corrugated.de>
                    Antworten an: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum: Mittwoch, 9. Januar 2019 um 17:21
                    An: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Betreff: Antwort: Re: Antwort: Re: Antwort: Re: Antwort: Re: Anyone got
experience with "protocol buffers" or DFDL (for generation of the message (de)serialization
code)?
            
                    The developer's struggle: Which foot to shoot yourself in. ;-)
            
                    I have no detailed knowledge about the protocols you want to serialize/deserialize
- maybe they are simple enough that the mentioned early serialization features of Kaitai are
sufficient. If not, I wouldn't recommend using it.
            
                    Another aspect might be the anticipated distribution of read and write
workloads of a typical PLC4X application - if its mostly reads it might still be worth a try,
because you save a lot of (implementation) effort on the deserialization which frees up resources
for serialization or other things in general.
            
                    Mit freundlichen Grüßen
                    Kind regards
            
                    Sebastian Wiendl
                    DSE / Digital Solutions Software Engineer
                    Phone: +49 9605 919 - 9341
                    E-Mail: SWiendl@bhs-corrugated.de
                    Internet: http://www.bhs-world.com
                    ________________________________
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                    ________________________________
            
            
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                    Von:        "Christofer Dutz" <christofer.dutz@c-ware.de>
                    An:        "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum:        09.01.2019 17:09
                    Betreff:        Re: Antwort: Re: Antwort: Re: Antwort: Re: Anyone got
experience with "protocol buffers" or DFDL (for generation of the message (de)serialization
code)?
                    ________________________________
            
            
            
                    Hi Sebastian,
            
                    yeah … I asked in the Incubator list and they told me it would be safe
to use, if the output was not GPLed …
            
                    so I contacted the maintainer of the project and simply asked him.
                    He told me that the output would match the input license. So if our definitions
would be Apache 2.0, so would the output … so it seems we would be safe and able to use
that.
                    However he also told me this:
            
                    “That's great news! Please note, however, that serialization is in its
                    early stages in Kaitai Struct, so it might be no exactly up to your
                    expectations.“
            
                    So I don’t know if we should go down that path … right now … :-/
            
                    Chris
            
            
            
                    Von: Sebastian Wiendl <SWiendl@bhs-corrugated.de>
                    Antworten an: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum: Mittwoch, 9. Januar 2019 um 16:46
                    An: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Betreff: Antwort: Re: Antwort: Re: Antwort: Re: Anyone got experience
with "protocol buffers" or DFDL (for generation of the message (de)serialization code)?
            
                    Another thing to consider: Last time I checked Kaitai only supported deserialization
(https://github.com/kaitai-io/kaitai_struct/issues/27). Might be inconvenient to introduce
another framework for serialization...
            
                    Mit freundlichen Grüßen
                    Kind regards
            
                    Sebastian Wiendl
                    DSE / Digital Solutions Software Engineer
                    Phone: +49 9605 919 - 9341
                    E-Mail: SWiendl@bhs-corrugated.de
                    Internet: http://www.bhs-world.com<http://www.bhs-world.com/>
                    ________________________________
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                    BHS Corrugated Maschinen- und Anlagenbau GmbH
                    Paul-Engel-Straße 1
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                    Management: Christian Engel, Lars Engel, Norbert Städele
                    Registered at Amtsgericht Weiden, HR B 1320
            
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                    ________________________________
            
            
                    Diese Nachricht ist nur für den Empfänger bestimmt, da sie persönliche
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                    Von:        "Christofer Dutz" <christofer.dutz@c-ware.de>
                    An:        "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum:        09.01.2019 15:57
                    Betreff:        Re: Antwort: Re: Antwort: Re: Anyone got experience with
"protocol buffers" or DFDL (for generation of the message (de)serialization code)?
                    ________________________________
            
            
            
                    The thing is that we would actually not be bundling that … the compiler
is only used during the build and not at runtime.
                    I am currently double-checking this with the others in the incubator mailing-list.
            
                    So it’s not completely impossible … let’s see what the others have
to say about it.
            
                    But I agree … it does look as if it would suit our needs.
            
                    Chris
            
            
                    Von: Sebastian Wiendl <SWiendl@bhs-corrugated.de>
                    Antworten an: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum: Mittwoch, 9. Januar 2019 um 15:42
                    An: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Betreff: Antwort: Re: Antwort: Re: Anyone got experience with "protocol
buffers" or DFDL (for generation of the message (de)serialization code)?
            
                    Yeah, i just checked... bummer the compiler is GPLed...
            
                    The project itself has some really good ideas how to handle binary parsing.
I used it prototypically in decoding a proprietary UDP message format and it worked great.
            
                    Mit freundlichen Grüßen
                    Kind regards
            
                    Sebastian Wiendl
                    DSE / Digital Solutions Software Engineer
                    Phone: +49 9605 919 - 9341
                    E-Mail: SWiendl@bhs-corrugated.de
                    Internet: http://www.bhs-world.com<http://www.bhs-world.com/><http://www.bhs-world.com/>
                    ________________________________
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                    BHS Corrugated Maschinen- und Anlagenbau GmbH
                    Paul-Engel-Straße 1
                    92729 WEIHERHAMMER
                    GERMANY
            
                    Management: Christian Engel, Lars Engel, Norbert Städele
                    Registered at Amtsgericht Weiden, HR B 1320
            
                    [cid:_2_147D4998147D45880050BA3BC125837D]
            
            
                    ________________________________
            
            
                    Diese Nachricht ist nur für den Empfänger bestimmt, da sie persönliche
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                    Von:        "Christofer Dutz" <christofer.dutz@c-ware.de>
                    An:        "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum:        09.01.2019 15:37
                    Betreff:        Re: Antwort: Re: Anyone got experience with "protocol
buffers" or DFDL (for generation of the message (de)serialization code)?
                    ________________________________
            
            
            
                    Hi Sebasitan,
            
                    thanks for that pointer … unfortunately I think we might be unable to
use this option as the compiler is GPLv3 licensed … that is a category X license.
                    Even if the compiler is not bundled with our software or used at runtime
(will probably only need it at compile-time), I doubt we would be allowed to use it.
            
                    But still I’ll look into it …
            
                    Chris
            
                    Von: Sebastian Wiendl <SWiendl@bhs-corrugated.de>
                    Antworten an: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum: Mittwoch, 9. Januar 2019 um 15:18
                    An: "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Betreff: Antwort: Re: Anyone got experience with "protocol buffers" or
DFDL (for generation of the message (de)serialization code)?
            
                    Hi,
            
                    maybe the Kaitai Struct project (https://kaitai.io/) can help you achieve
this?
            
                    Mit freundlichen Grüßen
                    Kind regards
            
                    Sebastian Wiendl
                    DSE / Digital Solutions Software Engineer
                    Phone: +49 9605 919 - 9341
                    E-Mail: SWiendl@bhs-corrugated.de
                    Internet: http://www.bhs-world.com<http://www.bhs-world.com/><http://www.bhs-world.com/><http://www.bhs-world.com/>
                    ________________________________
                    [cid:_1_0DB11BC80DB117CC004E9C08C125837D]
            
                    BHS Corrugated Maschinen- und Anlagenbau GmbH
                    Paul-Engel-Straße 1
                    92729 WEIHERHAMMER
                    GERMANY
            
                    Management: Christian Engel, Lars Engel, Norbert Städele
                    Registered at Amtsgericht Weiden, HR B 1320
            
                    [cid:_2_0DB128DC0DB124CC004E9C08C125837D]
            
            
                    ________________________________
            
            
                    Diese Nachricht ist nur für den Empfänger bestimmt, da sie persönliche
und/oder rechtlich geschützte Informationen und vertrauliche Informationen enthält.
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and/or privileged and confidential information.
                    The contents are not to be disclosed to anyone else than the addressee.
Unauthorized recipients are requested to comply with the above and to inform the sender immediately
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                    Von:        "Christofer Dutz" <christofer.dutz@c-ware.de>
                    An:        "dev@plc4x.apache.org" <dev@plc4x.apache.org>
                    Datum:        09.01.2019 15:06
                    Betreff:        Re: Anyone got experience with "protocol buffers" or DFDL
(for generation of the message (de)serialization code)?
                    ________________________________
            
            
            
                    Hi all,
            
                    Ok ... so protobuf seems to be semi-ideal ...
            
                    It seems that you can use it to model the structure of data. Protobuf
is good for generating model classes, parsers and serializers for a given model ... the binary
data-format is a result of this.
            
                    We want the opposite: We want to generate a model from a known output
data-format. In general this could be somehow achieved with protobuf, however it is very difficult
to produce the definition in a way that it is able to parse a given data format.
                    For example simply outputting one byte seems to be problematic. I was
able to somehow hack an enum and provide some extension to allow providing code values, but
we don't have the level of control we would need to and the result is not very readable.
                    I was able to quite easily setup the maven build to generate java code
for parsing and serializing a model ... so that was good.
            
                    DFDL looks as if it's ideal for describing the data format, however I
couldn't find tooling to generate model, parser and serializer from a DFDL definition. I subscribed
to our brother incubating project Daffodil and asked on their list ... perhaps I have to get
my hands dirty and implement the maven plugin and code generators as part of that project
... I am hoping not having to do that.
            
                    I'll check out Thrift in parallel  ;-)
            
            
                    Chris
            
            
            
                    Am 09.01.19, 11:19 schrieb "Christofer Dutz" <christofer.dutz@c-ware.de>:
            
                    From my first look at thrift some time ago, that's more about API and
not about the actual payload, is it?
            
                    How about I try to do a protobuf version of the "s7-protocol" and you
give thrift a try? Another option would be the DFDL option.
            
                    Chris
            
                    Am 09.01.19, 11:13 schrieb "Julian Feinauer" <j.feinauer@pragmaticminds.de>:
            
                        Hi Chris,
            
                        we worked (and work) with Thrift [1] at several places.
                        Thrift is a strong contender to protobuf and both have their specific
advantages and disadvantages.
                        Perhaps I would prefer Thrift as it comes from the Apache Ecosystm
(and supports more langauges) but generally, Tim can say more about working with Thrift.
            
                        Best
                        Julian
            
                        [1] https://thrift.apache.org/
            
                        Am 09.01.19, 10:45 schrieb "Christofer Dutz" <christofer.dutz@c-ware.de>:
            
                            Hi all,
            
                            while I’m currently working on refactoring the S7 driver to
a simpler structure so we can convert it to other languages more easily. A colleague of mine
pointed me to protobuf/protocol buffers from google [1]
                            From a quick look at it, it does seem as if it could suit our
needs quite nicely. I would like to try out if it’s possible to model the S7 data structures
in this way. If it works we could eventually quickly create something that serializes/deserializes
given data in any language …
            
                            It seems to be a lot simpler than the DFDL [2] I was thinking
of, so guess we have to find out if it has all the capabilities we need.
            
                            Any thoughts?
            
                            Chris
            
            
            
            
                            [1] https://developers.google.com/protocol-buffers/docs/javatutorial
                            [2] https://en.wikipedia.org/wiki/Data_Format_Description_Language
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
        
        
    
    

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