Groups > comp.lang.java.programmer > #11910

Re: Interplatform (interprocess, interlanguage) communication

From	BGB <cr88192@hotmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: Interplatform (interprocess, interlanguage) communication
Date	2012-02-10 10:25 -0700
Organization	albasani.net
Message-ID	<jh3k0f$mbj$1@news.albasani.net> (permalink)
References	(5 earlier) <26124274.18.1328738542263.JavaMail.geo-discussion-forums@pbks5> <jgv8og$6ac$1@news.albasani.net> <4f332c0a$0$288$14726298@news.sunsite.dk> <jgvh14$lr4$1@news.albasani.net> <4f345cb4$0$291$14726298@news.sunsite.dk>

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On 2/9/2012 4:54 PM, Arne Vajhøj wrote:
> On 2/8/2012 11:10 PM, BGB wrote:
>> On 2/8/2012 7:14 PM, Arne Vajhøj wrote:
>>> On 2/8/2012 8:49 PM, BGB wrote:
>>>> as noted, many people neither use schemas nor any sort of schema
>>>> validation. in many use-cases, schemas are overly constraining to the
>>>> ability of using XML to represent free-form data, or using them
>>>> otherwise would offer little particular advantage.
>>>
>>> xsd:any do provide some flexibility in schemas.
>>>
>>
>> yep, but one can wonder what is the gain of using a schema if one is
>> just going to use "xsd:any"?...
>
> You still have some structure.
>

probably.

>> it is also a mystery how well EXI behaves in this case (admittedly, I
>> have not personally looked into EXI in-depth, as I only briefly skimmed
>> over the spec a long time ago).
>
> No idea. But I would assume EXI supports what is valid XML and XSD.
>

yes, it is just that, IIRC, EXI uses the schema to know how to 
efficiently encode structures (values are directly coded), and falls 
back to a more naive strategy (describing the encoded tags) if the 
schema doesn't cover a given case.

admittedly, I am less certain, partly as skimming over the spec, 
admittedly I am not entirely certain how EXI works (would have to invest 
a bit more time in reading over the spec).

note: even in the worst case, the output will still likely be tiny vs 
textual XML.

more skimming... sudden mystery: if the format is a bitstream, why are 
they apparently using a byte-aligned scheme for storing integers?... 
(the cost here is that one has to then re-align with the next byte 
boundary, potentially wasting on average several bits).

>>>> say, if one is using XML for compiler ASTs or similar (say, the XML is
>>>> used to represent a just-parsed glob of source-code), do they really
>>>> need any sort of schema?
>>>
>>> I would expect syntax trees to follow certain rules and not be free
>>> form.
>>>
>>
>> well, there are some rules, but the question is more if a schema or the
>> use of validation would offer much advantage to make using it worth the
>> bother?...
>
> Enforcing correctness of data is usually a good idea.
>

potentially, but checking against schemas isn't free.
depending on the application, it could be hard to justify spending the 
extra clock cycles (except maybe for debugging purposes or similar).

a issue with ASTs is that they come in several forms:
giant, like in the output of a C compiler, where many tasks tend towards 
"expensive" (it may take easily anywhere from 250ms-1500ms to shove all 
this stuff through the various compiler stages);
small, like in a script-language VM, where typically it is desirable 
that compile times still be fairly fast, since a major strength of 
scripting languages is trying to keep "eval" and similar fairly close to 
free.

granted, one could debate the sanity of using XML for ASTs in the first 
place, but this started originally as a historical accident in my case 
(I was writing an interpreter, and it was what I had on-hand, actually: 
I partly hacked an existing XML-RPC implementation into being a script 
interpreter...). however, it doesn't seem to actually hurt performance 
too badly (ironically, in my C compiler, much more time goes into the 
preprocessor and tokenizer, which are far more efficient and more highly 
optimized).

side note: the C compiler doesn't use a standard DOM, but rather a 
highly specialized, but still DOM-like, system (and may still dump ASTs 
as text-form XML for debugging reasons). it involves, among other 
things, optimizations for numerical data (attributes may store numeric 
data directly, vs needing to use a string) and large hash-tables and 
chaining for look-ups, as well as specialized operations to reduce typing.

my current scripting VM, however, internally uses lists/s-expressions 
(note: they are neither AST compatible, nor will C code work effectively 
on my scripting VM). this was due to a later rewrite "switching over" (I 
was also reusing a lot of parts from a prior Scheme interpreter of mine 
for this one).

but, anyways, I am more left thinking schema-checking would probably 
make sense more when either some sort of security is a concern, or maybe 
when sending data "over the wire" between multiple parties.

inserting a schema check between ones' parser and ones' bytecode emitter 
doesn't seem nearly as compelling.

I guess, if a person really wanted, they could write a schema for the 
ASTs, but it is not clear how useful it would be to do so (since, 
generally, apart from someone mucking around with the compiler 
internals, there is little direct reason to know or care what is going 
on in there...).

or such...

Thread

Re: Interplatform (interprocess, interlanguage) communication jebblue <n@n.nnn> - 2012-02-07 12:11 -0600
  Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-07 16:38 -0700
    Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-07 20:26 -0400
      Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 01:41 -0700
        Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-08 07:19 -0400
          Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 12:07 -0700
            Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-08 21:16 -0500
              Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 19:50 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-09 06:24 -0400
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 09:15 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-09 18:58 -0400
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 16:15 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:50 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 21:40 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:47 -0500
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-11 12:06 -0800
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 15:18 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 23:03 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:27 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 13:33 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 15:50 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 14:34 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:48 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 21:46 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-10 08:51 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 10:43 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-10 13:15 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 14:50 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-10 14:32 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 17:10 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-10 22:08 -0400
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 00:49 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-11 14:04 -0400
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:55 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:52 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 20:06 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 22:41 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 00:46 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:29 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:31 -0500
                Re: Interplatform (interprocess, interlanguage) communication Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-12 16:02 +0000
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 11:16 -0500
                Re: Interplatform (interprocess, interlanguage) communication Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-12 22:46 +0000
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 11:33 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-11 20:18 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 01:36 -0700
                Re: Interplatform (interprocess, interlanguage) communication Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-02-12 13:52 -0600
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 14:43 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:49 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:46 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:45 -0500
        Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-08 14:02 -0800
          Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 18:49 -0700
            Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-08 21:14 -0500
              Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-08 20:07 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 23:29 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-09 09:40 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 17:02 -0700
              Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 21:10 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:54 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 10:25 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:45 -0500
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-11 12:14 -0800
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 15:20 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 22:20 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:23 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 12:13 -0700
    Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-07 20:24 -0500
    Re: Interplatform (interprocess, interlanguage) communication Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-08 01:31 +0000
      Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 00:55 -0700

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