Hi Chris, please see the Spec:
https://developers.google.com/protocol-buffers/docs/reference/java/com/google/protobuf/CodedInputStream https://developers.google.com/protocol-buffers/docs/reference/csharp/class/google/protobuf/coded-output-stream You can also read und write Int, float etc. Best regards Markus Mit freundlichen Grüßen Markus Sommer Geschäftsführer isb innovative software businesses GmbH Otto-Lilienthal-Straße 2 D 88046 Friedrichshafen Tel +49 (0) 7541 3834-14 Fax +49 (0) 7541 3834-20 Mobil +49 (0) 171 537 8437 Mail to [email protected] http://www.isb-fn.de Geschäftsführer: Markus Sommer, Thomas Zeler Registergericht: Amtsgericht Ulm HRB-Nr. 631624 Important Note: This e-mail and any attachments are confidential, may contain trade secrets and may well also be legally privileged or otherwise protected from disclosure. If you have received it in error, you are on notice of its status. Please notify us immediately by reply e-mail and then delete this e-mail and any attachment from your system. If you are not the intended recipient please understand that you must not copy this e-mail or any attachments or disclose the contents to any other person. Thank you. -----Ursprüngliche Nachricht----- Von: Christofer Dutz <[email protected]> Gesendet: Mittwoch, 9. Januar 2019 15:35 An: [email protected] Betreff: Re: Anyone got experience with "protocol buffers" or DFDL (for generation of the message (de)serialization code)? Hi Markus, Is there a way to enforce one-byte fields? All I could find was int32 and was told that 0-127 is encoded as one byte and as soon as the highest level bit is 1 another byte is added ... so serializing 0xFF would be a challenge. Also sometimes the type of an object defines part of the output ... so for example the type of object defines a constant value byte. Is this possible with protobuf? For example a "ReadVarParameter" outputs a constant of 0x04 as first byte ... Chris Am 09.01.19, 15:20 schrieb "Markus Sommer" <[email protected]>: Hello all, I used protobuf for a communication driver in C ++ for screwdriving. Simple structured messages can be modeled very well in proto -> classes. As the messages get more complex, modeling was no longer possible. I used the CodedInputStream and CodedOutputStream classes to read and generate the messages in protobuf. In the end, it always depends on the structure of the messages. best regards Markus Mit freundlichen Grüßen Markus Sommer Geschäftsführer isb innovative software businesses GmbH Otto-Lilienthal-Straße 2 D 88046 Friedrichshafen Tel +49 (0) 7541 3834-14 Fax +49 (0) 7541 3834-20 Mobil +49 (0) 171 537 8437 Mail to [email protected] http://www.isb-fn.de Geschäftsführer: Markus Sommer, Thomas Zeler Registergericht: Amtsgericht Ulm HRB-Nr. 631624 Important Note: This e-mail and any attachments are confidential, may contain trade secrets and may well also be legally privileged or otherwise protected from disclosure. If you have received it in error, you are on notice of its status. Please notify us immediately by reply e-mail and then delete this e-mail and any attachment from your system. If you are not the intended recipient please understand that you must not copy this e-mail or any attachments or disclose the contents to any other person. Thank you. -----Ursprüngliche Nachricht----- Von: Christofer Dutz <[email protected]> Gesendet: Mittwoch, 9. Januar 2019 15:17 An: [email protected] Betreff: Re: Anyone got experience with "protocol buffers" or DFDL (for generation of the message (de)serialization code)? Hi all, well that was quick ... I just had another deep-dive in Apache Thrift ... guess I was right: Seems Thrift is very similar to Protobuf as it helps define a model and have model, parsers and serializers generated from that. It looks as if it supports more transport protocols, but doesn't offer direct ways to provide custom protocols. My gut feeling tells me DFDL seems to be the best match for our needs, but also seems to be the option with a non-existing full tool stack :-( Chris Am 09.01.19, 15:06 schrieb "Christofer Dutz" <[email protected]>: 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" <[email protected]>: 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" <[email protected]>: 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" <[email protected]>: 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
