XML quote Re: Meeting Notes: SLUG Mon 14 Nov - Google Earth and everything else

[aluminumsulfate at earthlink.net]

> From: kclark at elbrysnetworks.com (Kevin D. Clark)
> Date: Tue, 14 Nov 2006 10:30:12 -0500

> Suppose this is version 1 of the protocol.
> 
> Now suppose in version 2 of the protocol we want to add some more
> properties:
> 
>    <foo>
>    <color>blue</color>
>    <height>1.3m</height>
>    <fav-dessert>pie</fav-dessert>
>    <weight>22kg</weight>
>    <fav-movie>Brazil</fav-movie>
>    </foo>

That's great, but when v3 of the protocol comes out, and the message
is encoded

    <foo>
    <color>blue</color>
    <height>1.3m</height>
    <favorites>
     <dessert>pie</dessert>
     <movie>Brazil</movie>
    </favorites>
    <weight>22kg</weight>
    </foo>

your v1 and v2 nodes are going to be incompatible with your v3 nodes.

On the other hand, if the communication protocol was formed solely of
grammatical Lojban text, this problem would never happen:

 la fus. se skari lo blanu
         gi'e mitre li papici loka clani
         gi'e rainei lo bavyvacysai poi se cmene zoi gy. pie .gy. ku'o
                  .e lo skina poi se cmene zoi gy. Brazil .gy. ku'o
         gi'e ki'ogra li rere

Easy as that.  :) The text will parse into a tree just like XML, but
with the advantage that standard rewriting rules can be used to
convert between different *representations* with the same *meaning*.
Hm.  Sounds like one of the original goals of SGML, doesn't it?