Re: [xml-dev] When is it appropriate/good to format data as XML?

["G. Ken Holman" <gkholman@CraneSoftwrights.com>]

I wonder if Randall Monroe follows XML-Dev and saw the humour in 
Friday's XML-Dev post when he wrote today's xkcd webcomic ... the 
quote that follows the link below is the alternative text one sees 
when hovering over the comic image:

  https://www.xkcd.com/2116/
  "At some point, compression becomes an aesthetic design
   choice. Luckily, SVG is a really flexible format, so
   there's no reason it can't support vector JPEG artifacts."

. . . . . . Ken

At 2019-02-22 18:06 +0000, Costello, Roger L. wrote:
> Hi Folks,
>
> Clearly the marketplace does not believe that XML is 
> appropriate/good for every type of data.
>
> Consider:
>
> - Although there is an XML format for image data (SVG), most images 
> in use today are not formatted as XML/SVG. Most images are formatted 
> as binary JPEG, GIF, PNG, etc. files.
>
> Why is that?
>
> Why is it that there is far more usage of JPEG than SVG?
>
> Is it simply because an XML-encoding of image data is too huge? Is 
> size the reason? Or is there more to it?
>
> The JPEG standard was defined prior to XML. There existed JPEG 
> parsers and tools well before there existed XML parsers and tools. 
> Perhaps the reason that JPEG was never supplanted by XML is simply 
> because of inertia - it would have taken too much effort and expense 
> to replace the existing JPEG toolset?
>
> Wikipedia says that XML "defines a set of rules for encoding documents."
>
> Perhaps image data is not document-oriented; is that why most images 
> are not in the XML format?
>
> Note: I am not clear what it means for data to be (or not be) 
> document-oriented.
>
> XML-formatted data can be beautiful.
>
> Binary-formatted data can also be beautiful.
>
> Scenario: There exists data about a person's name and date of birth 
> (DOB). The data consists of an ASCII string representing the 
> person's name and an ISO 8601 date-time string value representing 
> the DOB. We may wrap the text data in tags to produce XML such as this:
>
> <Person>
>     <Name>John Doe</Name>
>     <DOB>2000-02-06T20:13:35</DOB>
> </Person>
>
> Alternatively, the data might consist of a 4-byte integer 
> representing the person's DOB in number of seconds since Epoch and a 
> null-terminated ASCII string representing the person's name. The 
> name and DOB can be compactly represented in binary with this series 
> of hex digits:
>
> 4A 6F 68 6E 20 44 6F 65 00 EF D5 9D 38
>
> You might argue that this series of hex digits is not readable, but 
> to a machine it can be very readable (processable).
>
> Both formats are beautiful.
>
> With DFDL (Data Format Description Language) we have tremendous 
> agility in converting binary to XML and vice versa.
>
> When is it appropriate/good to format data as XML?
>
> When is it *not* appropriate/good to format data as XML?
>
> /Roger

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