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Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

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Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#61

Post by lucian1900 »

bhaak wrote: post #15

What's with all the XML hate? Of course, doing everything in XML is a stupid idea (e.g. XSLT and Ant) and thanks heaven that hype is over. But if I want something that is able to express data structures customized by myself, usually with hierarchical data that can be verified for validity and syntax (XML Schemas or old-school DTD), what other options are there? Doing hierarchical data in SQL is a bitch and if you wan…

Similarly, what's with the binary format/protocol hate? That's what brought us our current extremely common mishandling of text encoding.

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#62

Post by icebraining »

bhaak wrote: post #47
icebraining wrote: post #28

Earlier quoted context omitted.

How so? XML by itself only supports strings; any other data types have to be derived from a schema. But you can do the same with any other format that supports strings, including JSON.

But in the design of XML this was already acknowledged. That's why there is the distinction between well-formed and valid XML documents. Only with valid XML documents there is a schema attached that will describe these nodes with the type attribute. And because it is extendable, these types can be anything but they will be automatically validated by the parser. JSON OTOH doesn't have this extensibility. There are a c…

Only with valid XML documents there is a schema attached that will describe these nodes with the type attribute.

http://json-schema.org/

What's the issue?

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#63

Post by bananas »

icebraining wrote: post #59
bananas wrote: post #32

Earlier quoted context omitted.

One of the core aspects of XML that is really important is that no typing is inferred by the structure of the file unlike JSON. JSON is by nature tied to the JavaScript type system which is sparse and inaccurate. For example, if you look at the following: { "name": "bob", "salary": 1e999 } Ah crap! Deserializer blew (in most cases silently converting the number to null) bob 1e999 No problem. The consumer can throw th…

And the following is not acceptable as it breaks the semantics of JSON and requires a secondary deserialisation step as strings ain't numbers... XML strings ain't numbers neither. You can throw a big decimal deserialiser (e.g. as a custom deserialization adapter) at a JSON document as well.

Let's break this down into two statements:

XML doesn't have strings (or types at all really)

JSON strings are strings.

There is a massive semantic difference here when it comes to parsing.

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#64

Post by rbehrends »

_pmf_ wrote: post #54
rbehrends wrote: post #43

Earlier quoted context omitted.

XML is unnecessarily verbose, for the supposed sake of human readability. But used as a serialization format, it isn't really readable or editable by humans (except in the sense that a Turing machine is programmable): remember that the ML in XML stands for "markup language", and SGML, its predecessor, was designed as a way of marking up normal text, not littering data with angular brackets and identifiers. (XML/SGML…

You fail to address OP's question: > But if I want something that is able to express data structures customized by myself, usually with hierarchical data that can be verified for validity and syntax (XML Schemas or old-school DTD), what other options are there?

I did address it. Did you read my comment until the end?

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#65

Post by bhaak »

_pmf_ wrote: post #54
rbehrends wrote: post #43

Earlier quoted context omitted.

XML is unnecessarily verbose, for the supposed sake of human readability. But used as a serialization format, it isn't really readable or editable by humans (except in the sense that a Turing machine is programmable): remember that the ML in XML stands for "markup language", and SGML, its predecessor, was designed as a way of marking up normal text, not littering data with angular brackets and identifiers. (XML/SGML…

You fail to address OP's question: > But if I want something that is able to express data structures customized by myself, usually with hierarchical data that can be verified for validity and syntax (XML Schemas or old-school DTD), what other options are there?

He actually did address my question in a way: "[...] XML has prevented the adoption of something better (because it was "good enough")."

Which IMO is a sensible way looking at it. I too think XML is not perfect but if all the other stuff we're stuck with currently would be as good enough as XML, IT would be a place with less WTFs all around. ;-)

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#66

Post by ctb_mg »

turnip1979 wrote: post #34
oneeyedpigeon wrote: post #27

Earlier quoted context omitted.

How is YAML a superset of JSON? Do you mean 'conceptually'?

To be specific, JSON syntax is a subset of YAML version 1.2. However, I hate YAML with a passion. It is worse than XML in my books. I can usually read JSON fine. I can also read XML in many cases. For the life of me, I just can't read YAML. It has something to do with "-", line indentation and different ways of writing lists. Of course, someone will say YAML is technically better ...

Same here, it is very difficult for me to tell levels of nested structures in yaml. Though I'm sure if I sat down and read up on it I could force it into my brain. But shouldn't it be intuitive to read without that?

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#67

Post by sparkie »

bhaak wrote: post #15

What's with all the XML hate? Of course, doing everything in XML is a stupid idea (e.g. XSLT and Ant) and thanks heaven that hype is over. But if I want something that is able to express data structures customized by myself, usually with hierarchical data that can be verified for validity and syntax (XML Schemas or old-school DTD), what other options are there? Doing hierarchical data in SQL is a bitch and if you wan…

The problem with XSD and DTD is they only offer primitive ways to validate data, and it takes significant effort to validate some data (eg,[ https://stackoverflow.com/questions/3382944 ]). As a result, there have been a bunch of other XML schema validators created to counter these problems, but we should really ask why we need to keep inventing new languages when the existing ones turn out to be insufficient.

If we start out instead with something that's turing complete and simple to begin with (perhaps S-expressions?), we can (often trivially) write our own validators/type-checkers, or any other processing tool to verify the document structure, with few or no constraints, and without requiring the effort and expertise to parse complex syntax.

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#68

Post by jules »

bananas wrote: post #32
Sharlin wrote: post #16

Earlier quoted context omitted.

The issue is probably that 99.999% of all XML use cases don't use (or need) the verification aspect. For all of those, XML is overkill. Besides, surely it would be possible to design a verification layer on top of JSON, for instance - the fact that one does not currently exist does not mean that XML (and abuse of XML!) should not be criticized.

One of the core aspects of XML that is really important is that no typing is inferred by the structure of the file unlike JSON. JSON is by nature tied to the JavaScript type system which is sparse and inaccurate. For example, if you look at the following: { "name": "bob", "salary": 1e999 } Ah crap! Deserializer blew (in most cases silently converting the number to null) bob 1e999 No problem. The consumer can throw th…

The equivalent of your XML would be:

    {"name": "bob", "salary": "1e999"}

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#69

Post by e12e »

bananas wrote: post #13

I think this title is wrong. Firstly some clarification - this appears to just be about the persistence format for his dive log. It was XML, now it's git based with plain text. As someone who had to manage a system which worked with plain text files structured in a filesystem for a number of years in the 1990s, this is done to death already. You now end up with the following problems: locking, synchronising filesyste…

> You now end up with the following problems: locking, synchronising filesystem state with the program, inode usage, file handles to manage galore and concurrency. All sorts.

Which is why he's reusing git for resolving those pain points? Well presumably all except "synchronizing filesystem state with the program" -- where he's gone from using some kind of xml parser to marshal xml to objects/structs in ram to using a (simple(r)?) text parser to do the same.

I'm guessing he just writes/reads a full (part) of a log (a branch of the full tree, or whatever is used in the program. Maybe a list anchored at a date?) -- and lets git sort the history/backup thing.

So, yes, it's a different format, but I think the argument you're making is off -- seeing as he already has git for that? It's more like combining Maildir (or mboxes, only commited when valid) and git.

Re: Linus Torvalds: “I'm happily hacking on a new save format using ‘libgit2’”

#70

Post by bhaak »

icebraining wrote: post #62
bhaak wrote: post #47

Earlier quoted context omitted.

But in the design of XML this was already acknowledged. That's why there is the distinction between well-formed and valid XML documents. Only with valid XML documents there is a schema attached that will describe these nodes with the type attribute. And because it is extendable, these types can be anything but they will be automatically validated by the parser. JSON OTOH doesn't have this extensibility. There are a c…

Only with valid XML documents there is a schema attached that will describe these nodes with the type attribute. http://json-schema.org/ What's the issue?

It's still a draft (and if I may nit-pick, an expired draft).

It only has "complete structural validation". Which means it doesn't feature custom types.

Although it adds a workaround for the date issue by adding a handful of supported sub-types (http://json-schema.org/latest/json-schema-validation.html#an...)

It is far from what validation XML Schemas offer.

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