Re: [xml-dev] Formatless files

And sometimes what is a "program" and what is a file is not well defined.

Data can be programs, and programs can be data -- depending on who is the observer:

Passing a function as a parameter to another function. In this case the parameter is kind of "data' for the 2nd function.
Loading an XPath function library from a file. This is "data" for the loader, but "code/program" for the importer.
The swap file is data for an OS that supports virtual memory, but is maybe "all the program" for the program, without it actually being aware of this.

Thanks,

Dimitre

On Sun, Aug 14, 2022 at 3:02 PM Michael Kay <mike@saxonica.com> wrote:

>
> There are many cases when we don't want "any program" to read our file. And by "read" I mean "understand / get / extract the useful information".
>
> Consider a file that contains the hashes of (salted) network-ids and/or passwords of the users in an organization, or a smaller subset of this organization.
>

A classic example was an online game we played as students called "moo" - think Wordle, but 50 years earlier - that maintained a shared file containing the league table of everyone's scores. The program needs read and write access to the file, but the user playing the game must be prohibited from accessing the file directly. Today's commodity operating systems don't make this easy: it typically requires multiple processes.

Michael Kay
Saxonica