How to respond with a valid json ?

Hi,
nice work with webdatarocks, thanks… but I have a question.
How can I send to the client a json result with the data types included ? How is it possible if the json object demonstrated here Data Types is not a a valid json object ?
The first object is not valid because it uses curly brackets instead of a string or a number right after of the first field’s name.
All the examples that I saw uses a static json with all fields configured and all values setted, but how can I put this to work in the real world if my server just can’t respond with an invalid json (with the invalid first configuration object) ?
Thanks in advance !
Regards,
Rafael