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Re: Static JSON parser for embedded

From pozz <pozzugno@gmail.com>
Newsgroups comp.lang.c, comp.arch.embedded
Subject Re: Static JSON parser for embedded
Date 2019-06-06 11:12 +0200
Organization A noiseless patient Spider
Message-ID <qdaldp$o7c$1@dont-email.me> (permalink)
References <qblnbg$402$1@dont-email.me> <2hODE.56712$8B4.29775@fx02.iad> <qbp3ce$j92$1@dont-email.me> <Aj0EE.52260$fq3.52080@fx07.iad>

Cross-posted to 2 groups.

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Il 19/05/2019 01:12, Clifford Heath ha scritto:
> On 19/5/19 12:03 am, pozz wrote:
>> Il 18/05/2019 09:14, Clifford Heath ha scritto:
>>> On 17/5/19 5:20 pm, pozz wrote:
>>>> I'd like to use JSON documents in my embedded project. I don't need 
>>>> full parsing capabilities, because JSON could be very complex in 
>>>> general.
>>>>
>>>> Do you know of something code generator?
>>>
>>> Ok. Latecomer, but I read most of the thread. Introduction: I've been 
>>> writing C since 1979 and have a million lines of my code in 
>>> production in mission-critical software on tens of millions of 
>>> enterprise computers. Although these days my C is mostly C++, I use 
>>> C++ mostly for the features that make it "a better C".
>>>
>>> Neither JSON nor C has a very strong type system. Neither is a good 
>>> specification language. You should choose a specification language 
>>> that does a good job of specifying your intent, and a compiler for it 
>>> that emits C that handles one or more packing syntaxes such as JSON 
>>> (if you must!)
>>>
>>> The European Space Agency has followed the lead of the ISO networking 
>>> standards and built a compiler for ASN.1, which emits C code targeted 
>>> at static-memory embedded systems. The downside: I don't think it has 
>>> a JSON packing rule (the ASN.1 name for a transfer syntax). Other 
>>> ASN.1 compilers do support JSON, but I don't know whether they target 
>>> static-memory or embedded systems.
>>>
>>> The ESA-funded ASN1CC is here: <https://github.com/ttsiodras/asn1scc>.
>>>
>>> It supports BER (Basic encoding rules, a compact & fast binary 
>>> format), PER (Packed Encoding Rules, a bit-packed binary format that 
>>> will be slower but tighter), XER (XML Encoding Rules, you can 
>>> imagine!), and ACN, where you get to define the encoding yourself.
>>>
>>> If you wish to serve the community as well as yourself, write JER, 
>>> JSON Encoding Rules and submit it.
>>>
>>> A quick search finds a proposed standard: 
>>> <https://www.obj-sys.com/docs/JSONEncodingRules.pdf> and a tool that 
>>> analyses a JSON fragment and produces a proposed ASN.1 definition for 
>>> the shape of the fragment <https://asn1.io/json2asn/>
>>>
>>> So there is existing work, and no doubt community support for more.
>>> You could do a lot worse than start with ASN1CC.
>>
>> ASN.1 is interested. I will look at it more deeply.
>>
>> Just a simple question. Are optional fields possible in a message?
> 
> Yes. And pretty-much everything else you might need in a static type 
> system; sets of alternates with a discriminator (discriminated unions), 
> arbitrary nesting of arrays of structures of arrays of structures, 
> strings of many and various character sets and encodings, enumerations, 
> numbers limited by range not storage size, etc.
> 
> Not all ASN.1 implementations are equal. This one is targeted at systems 
> that use no dynamic memory allocation, which is truly an excellent thing 
> - but you probably can't do JSON like that. It's used for the majority 
> of inter-module communications on ESA space missions, so it's pretty 
> well tested and reliable too.
> 
> The point is that the ASN.1 definitions are focussed on defining the 
> values that can be meaningfully transferred, not the possible values of 
> a set of representations. It's not fully powerful, but it's a lot better 
> than most programming languages.
> 
> I plan to emit ASN.1 from my Constellation Query Language tools at some 
> stage this year, see <http://dataconstellation.com/ActiveFacts/>. CQL 
> has a complete first-order logic constraint language, so it is even more 
> powerful than ASN.1; and every feature (definition, constraint) is also 
> expressible in controlled natural language and *compilable* from that 
> language.

Incredibly, it seems there isn't any ASN.1 PER codec for 
javascript/typescript (web-oriented) world. This limits the use to BER 
only :-(

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Thread

Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-17 09:20 +0200
  Re: Static JSON parser for embedded Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-05-17 08:48 +0000
    Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-17 11:06 +0200
      Re: Static JSON parser for embedded Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-05-17 11:22 +0000
        Re: Static JSON parser for embedded Thiago Adams <thiago.adams@gmail.com> - 2019-05-17 04:40 -0700
          Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-17 14:10 +0200
            Re: Static JSON parser for embedded Thiago Adams <thiago.adams@gmail.com> - 2019-05-17 05:18 -0700
              Re: Static JSON parser for embedded Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-05-18 18:18 +0000
        Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-17 14:10 +0200
          Re: Static JSON parser for embedded Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-05-18 18:22 +0000
  Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-17 11:39 +0100
    Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-17 13:19 +0200
      Re: Static JSON parser for embedded Thiago Adams <thiago.adams@gmail.com> - 2019-05-17 05:09 -0700
        Re: Static JSON parser for embedded Thiago Adams <thiago.adams@gmail.com> - 2019-05-17 05:15 -0700
      Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-17 15:06 +0100
        Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-17 16:37 +0200
          Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-17 17:56 +0100
            Re: Static JSON parser for embedded "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-05-17 10:21 -0700
              Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-17 18:43 +0100
                Re: Static JSON parser for embedded Thiago Adams <thiago.adams@gmail.com> - 2019-05-17 10:58 -0700
                Re: Static JSON parser for embedded "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-05-17 11:16 -0700
                Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-17 19:43 +0100
                Re: Static JSON parser for embedded "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-05-17 11:57 -0700
                Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-17 20:11 +0100
                Re: Static JSON parser for embedded "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-05-17 12:22 -0700
                Re: Static JSON parser for embedded Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-05-17 21:33 +0100
                Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-18 00:11 +0200
            Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-17 22:33 +0100
              Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-18 00:17 +0200
                Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-18 01:25 +0100
            Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-17 23:43 +0200
  Re: Static JSON parser for embedded Thiago Adams <thiago.adams@gmail.com> - 2019-05-17 04:38 -0700
  Re: Static JSON parser for embedded "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-05-17 07:38 -0700
    Re: Static JSON parser for embedded Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-05-17 08:05 -0700
      Re: Static JSON parser for embedded "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-05-17 08:15 -0700
      Re: Static JSON parser for embedded Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2019-05-17 11:53 -0400
  Re: Static JSON parser for embedded Ian Collins <ian-news@hotmail.com> - 2019-05-18 15:33 +1200
    Re: Static JSON parser for embedded Bart <bc@freeuk.com> - 2019-05-18 11:57 +0100
  Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-05-18 17:14 +1000
    Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-05-18 16:03 +0200
      Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-05-19 09:12 +1000
        Re: Static JSON parser for embedded Niklas Holsti <niklas.holsti@tidorum.invalid> - 2019-05-19 17:13 +0300
          Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-05-20 09:25 +1000
        Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-06-06 11:12 +0200
          Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-06-07 09:11 +1000
            Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-06-07 08:59 +0200
              Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-06-12 09:41 +1000
    Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-06-05 16:44 +0200
      Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-06-06 09:27 +1000
        Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-06-06 09:50 +0200
          Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-06-07 09:08 +1000
      Re: Static JSON parser for embedded Clifford Heath <no.spam@please.net> - 2019-06-06 09:48 +1000
        Re: Static JSON parser for embedded pozz <pozzugno@gmail.com> - 2019-06-06 09:54 +0200

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