Re: [xml-dev] The illusion of simplicity and low cost in data designand

[Michael Kay <mike@saxonica.com>]

I think protocol designers got this right: there's a stack of formats (protocols) with raw bytes at one level, character streams at another, generic syntax such as XML and JSON at a third, and semantics such as XBRL or SVG layered on top of that. And the protocols are labelled and identified so the recipient knows what they're seeing. If the character stream is in particular encoding, the protocol at that layer labels it as such and the recipient is able to decode it.

File system designers, at least for commodity operating systems, never achieved this. The operating system itself knows nothing about the file; applications are left to guess by making inferences from the file name extension, or by sniffing the content, all of which is unreliable and insecure. Conventions like putting the encoding in a header, or using strings like xmlns="..." to identify the vocabulary, are ad-hoc and unsystematic, and they're very often at the wrong level of the system (you should know the encoding before you start trying to interpret the characters).

Eric Raymond's quote would be valid if the operating system constrained all files to be XML, say. But it's not valid for an operating system that can support any file format, but can also reliably tell the application that it's reading an XML file rather than a JSON file (or more precisely, one that can identity the application that wrote the file and tell you what claims that application made about the file format).

If file systems were layered like protocols are, we would have much more robust applications.

Michael Kay
Saxonica

> On 11 Aug 2022, at 21:23, Roger L Costello <costello@mitre.org> wrote:
> 
> Yesterday Michael Kay wrote:
> 
> A common phenomenon in the history of computing: simplicity and low cost wins over technical sophistication. Something which is now causing the industry huge costs because the popular operating systems are so insecure.
> 
> In his book, "The Art of Unix Programming" Eric Raymond writes:
> 
> Many operating systems touted as more "modern" or "user friendly" than Unix achieve their surface glossiness by locking users and developers into one interface policy, and offer an application-programming interface (API) that for all its elaborateness is rather narrow and rigid. On such systems, tasks the designers have anticipated are very easy--but tasks they have not anticipated are often impossible or at best extremely painful.
> 
> Really interesting! 
> 
> Both quotes suggest that buying into what appears to be a simple, low cost solution may ultimately end up costing more and require complex extensions.
> 
> The XML stack of technologies is pretty hefty, which turns off some people. However, as the quotes from Michael and Eric suggest, the simplicity and low cost of some other data technology may turn out to be an illusion.
> 
> Comments?
> 
> /Roger 
> 
> 
> 
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