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"Interoperability is getting better" ... What does that mean?

• From: "Costello, Roger L." <costello@mitre.org>
• To: "xml-dev@lists.xml.org" <xml-dev@lists.xml.org>
• Date: Sun, 30 Dec 2012 13:10:31 +0000

Hi Folks,

Several people have stated:

    Interoperability, on the whole,
    does seem to be getting better.

In the context of our discussion on character encoding, what does that mean?

I will take a stab at defining what it means:

Interoperability means that you and I interpret (decode) the bytes in the XML file in the same way.

Example: I create an XML file and I encode all the characters in it using UTF-8. Here is a graphical depiction (i.e., glyphs) of the bytes that I send to you:

    <Name>López</Name>

You receive my XML document but you interpret the bytes as iso-8859-1. 

Oops! 

Now the trouble begins.

In UTF-8 the ó is a graphical depiction of the LATIN SMALL LETTER O WITH ACUTE character and it is encoded inside the computer using these two bytes: C3 B3

But in iso-8859-1 the two bytes C3 B3 is the encoding of two characters:

     C3 is the encoding of the à character
     B3 is the encoding of the ³ character

Thus, you interpret the XML as:

    <Name>López</Name>

We are interpreting the same XML document (i.e., the same set of bytes) differently.

Interoperability has failed.

So, when we say: 

    Interoperability is getting better.

we mean that the number of occurrences of senders and receivers interpreting the bytes in an XML document is decreasing.  

Is that correct?

/Roger

• Follow-Ups:
  • Re: "Interoperability is getting better" ... What does that mean?
    • From: Chris Maloney <voldrani@gmail.com>