Re: First write up of JSON

Hi Steven,

1) New MIPs bad, extra attributes good :-)

2) Perhaps the json attributes should be namespace qualified so that they 
are easily seen to not be part of the data, e.g. <location 
json:type="array">Lyon</location> and <_foo json:name="$foo">...</_foo>. 
Obviously not strictly necessary since there can be no attributes for 
other reasons; also, if done, would mean declaring the json namespace on 
the root json element.

3) I think you meant to send the wiki link to the readable version (
http://www.w3.org/MarkUp/Forms/wiki/Json) rather than the wiki link to the 
editable version.

Cheers,
John




From:
"Steven Pemberton" <Steven.Pemberton@cwi.nl>
To:
"Forms WG" <public-forms@w3.org>
Date:
11/02/2010 02:09 AM
Subject:
First write up of JSON



Following on our productive JSON discussion yesterday 
(http://www.w3.org/2010/11/01-forms-minutes.html#item03) I have written it 
 
up on the wiki page

                 
http://www.w3.org/MarkUp/Forms/wiki/index.php?title=Json&action=submit

However, in writing it up, I came to some slightly different conclusions.

The main discussions was on how to deal with empty and single-element 
arrays. Since an array like

                 {"company":"example.com", "locations":[{"place": 
"Amsterdam"},{"place": 
"London"}]

gets transformed to
                 <json><company>example.com</company>
                    <locations><place>Amsterdam</place>
                               <place>London</place>
                    </locations>
                 </json>

then

                 {"company":"example.com", "locations":[{"place": 
"Amsterdam"}]

would appear as

                 <json><company>example.com</company>
                    <locations><place>Amsterdam</place></locations>
                 </json>

which would be indistinguishable from

                 {"company":"example.com", "locations":{"place": 
"Amsterdam"}}

So, in order to be able to re-serialise correctly, the system needs to be 
able to distinguish the two cases. The conclusion we came to in the 
meeting was to use new sorts of MIP, usually used internally to the 
system, so that the system knows that an element actually represents an 
array. But then when the instance doesn't originate from externally, but 
is created from within the form, you need a way to set the MIP:

                 <bind ref="locations" json-array="true()"/>

which means new XForms facilities.

While writing it up, I realised that the alternative solution of using 
attributes would not require new XForms facilities. The knowledge is then 
exclusively in the parse and synchronise parts. So now the above array 
gets read as

                 <json><company>example.com</company>
                    <locations 
type="array"><place>Amsterdam</place></locations>
                 </json>

There is no chance of name clashes, since there are no attributes in JSON.

Steven