Re: What ASN.1 got right
Tim Bray <tbray@textuality.com> Tue, 02 March 2021 02:40 UTC
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From: Tim Bray <tbray@textuality.com>
Date: Mon, 01 Mar 2021 18:40:35 -0800
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Subject: Re: What ASN.1 got right
To: Nico Williams <nico@cryptonector.com>
Cc: Larry Masinter <LMM@acm.org>, IETF-Discussion Discussion <ietf@ietf.org>
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ASN.1 always had data types, and then XML came along, which had no data types but a pretty good system for associating names with chunks of data, and successfully invaded most of ASN.1's space. At which point I concluded that it's more important to know something's name than its data type. On Mon, Mar 1, 2021 at 6:18 PM Nico Williams <nico@cryptonector.com> wrote: > On Mon, Mar 01, 2021 at 05:34:55PM -0800, Larry Masinter wrote: > > JSON-LD seems to fit modern needs from an extensibility / simplicity > point > > of view. > > I know nothing about JSON-LD. > > > All the bit-packing goodness of various encodings are dreadful from an > > interoperability point of view. > > Rich formalisms and separation of syntax and "encoding rules" seem > > counter-productive. > > The nicest thing about XML is XSLT/XPath, and the nicest thing about > JSON is jq. Such languages are probably only feasible when you have > loose typing, which XML and JSON do. And loose typing does arguably > mean dispensing with the formalisms that force static typing. > > That said, and as much as I love jq, for all the protocols I work on I > would much rather have static typing and rich formalisms. Especially in > security protocols, I'd rather have rich formalisms. > > As always, one should use the right tool for the job. (FWIW, I used to > maintain jq and might again, and I maintain an ASN.1 implementation.) > > I don't see how separation of syntax and encoding can be counter- > productive: alternative syntaxes are always possible, and transcoding is > generally possible, and people often have to do these things for some > reason. > > As to "bit-packing"... have you noticed that every textual encoding > eventually evolves a binary adaptation? XML has FastInfoSet. JSON has > a multitude of binary encodings (at least three). Parsing textual > encodings isn't easy, and much less parsing them efficiently. Parsing > dynamically typed data requires more overhead than parsing statically > typed data. > > Parsing JSON efficiently is really hard. Parsing anything without a > schema shifts a lot of burden onto the developer, unless the developer > is using something like jq. People have devoted a lot of effort to > using SIMD to parse JSON more quickly than can be done on a traditional > CPU, but IIUC there are no online JSON parsers that use SIMD -- no one > would bother doing this for XDR because there is no need. > > XDR was always simpler to compile or hand-roll codecs for than TLV > encodings, and definitely than textual encodings. I've never heard a > bad thing uttered about XDR. > > It turns out that once you've parsed the syntax into an AST it's pretty > trivial to generate codecs (possibly bytecoded) regardless of the > encoding rules' nature. > > XDR being so much simpler than TLV types because of the absence of tags > and wasteful lengths, was always easy to handle, but what made it easy > was not having any crutches and so having to have parsed the syntax > defining the types one needed to encode. There's a lot of hand-rolled > XDR out there as well, including some I look after, because it's much > easier to hand-roll XDR than TLV encodings, and certainly than textual > ones. > > NDR's pointer dedup feature made it much harder to implement, but > otherwise it's really similar to XDR. OER and PER are not too > dissimilar to XDR, so they're probably comparable to XDR in > implementaiton complexity. > > Nico > -- > >
- Re: What ASN.1 got right Michael Thomas
- What ASN.1 got right Nico Williams
- RE: What ASN.1 got right Larry Masinter
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Tim Bray
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Keith Moore
- Re: What ASN.1 got right Theodore Ts'o
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Carsten Bormann
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Dirk-Willem van Gulik
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Dirk-Willem van Gulik
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right George Michaelson
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Christian Huitema
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right George Michaelson
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Jared Mauch
- Re: What ASN.1 got right Keith Moore
- Re: What ASN.1 got right Phillip Hallam-Baker
- Re: What ASN.1 got right Dirk-Willem van Gulik
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Nico Williams
- Re: What ASN.1 got right Michael Thomas
- TLS on disconnected/intermittently connected netw… Keith Moore
- Re: What ASN.1 got right Keith Moore
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Keith Moore
- Re: What ASN.1 got right Michael Thomas
- Re: What ASN.1 got right Keith Moore
- Re: What ASN.1 got right Michael Thomas
- Re: TLS on disconnected/intermittently connected … Viktor Dukhovni
- Re: TLS on disconnected/intermittently connected … Keith Moore
- Re: TLS on disconnected/intermittently connected … Sam Hartman
- Re: TLS on disconnected/intermittently connected … Keith Moore
- Re: TLS on disconnected/intermittently connected … Viktor Dukhovni
- Re: TLS on disconnected/intermittently connected … Sam Hartman
- Re: TLS on disconnected/intermittently connected … Keith Moore
- Re: TLS on disconnected/intermittently connected … Michael Thomas
- Re: TLS on disconnected/intermittently connected … Keith Moore
- Re: TLS on disconnected/intermittently connected … Michael Richardson