Fwd: Re: [xml-dev] Converting other data formats to XML, where theother

[Rick Jelliffe <rjelliffe@allette.com.au>]

---------- Forwarded message ----------
From: "Rick Jelliffe" <rjelliffe@allette.com.au>
Date: 24 Apr 2017 11:10 PM
Subject: Re: [xml-dev] Converting other data formats to XML, where the other data formats allow control characters
To: "Costello, Roger L." <costello@mitre.org>
Cc:

Answer #2.  The box really contains 3 x 4byte fields.The second four bytes contain an ASCII signature that gives as much as you need to know to know to reconstruct the JPEG.  

So make 3 attributes, one hex for the first 4bytes, othe second unicodebrestrictef to ASCII, the third hex again. The body of the jpeg use bin64.

Rick

On 24 Apr 2017 9:51 PM, "Costello, Roger L." <costello@mitre.org> wrote:

Hi Folks,

So, you want to convert this JSON to XML:

{
  "key":"\u0000"
}

 

\u0000 is a JSON encoding of the NUL (hex 0) character. Recall that the NUL character is not allowed in XML. What will you do with that NUL character? Will you discard it? But that means you have a lossy conversion. Round-tripping will not be possible.

 

So, you want to convert a JPEG2000 file to XML. The “file type box” contains a series of compatibility list fields. The JPEG2000 standard says this about each field:

 

This field is encoded as a four-byte string of ISO/IEC 646 characters.

 

Here is a compatibility list field from one JPEG2000 file (hex bytes):

 

00 00 00 B5

 

How will your XML represent that four-byte encoding of a string, given that hex 0 (NUL) is not a valid character in XML?

 

Question:

People are converting JSON to XML. People are converting JPEG2000 to XML. How are they handling characters that are allowed in JSON and JPEG2000 but are not allowed in XML?

 

/Roger