I’ve been making requests by doing find/replace on the XML held in strings. (Not using Ruby.) It works, but seems backwards since my IDE will do code-assist on JSON.

Btw, I like your use of HTTP statusCodes for error messages. Very intuitive. Good use of existing functionality. I’m used to web services where the error message is in the response XML. (See bellsouth or Qwest’s electronic ordering web service responses.) Instead of parsing XML for an error code, I can check the HTTP status code… if it’s not 200, then I know something went wrong… no parsing. Quick n’ easy.

Another nice thing is that the API supports Conditional GET, PUT and DELETE. Unfortunately you don’t see these often in web APIs, but they can be very useful when integrating with the Lypp API.

Conditional GET allows you to say “return something only if its changed since last time I saw it”. This is extremely efficient when nothing has changed, and adds virtually no overhead in the cases when something has.

Conditional PUT and DELETE basically allow you to update or delete something as long as it *has not* changed since you last saw it. Conditional PUT in particular is very useful, since it can act as a sort of optimistic locking system; making it so you can’t overwrite changes made by someone or something else.

I’ll be updating the Lypp API documentation to include more details, specifically how to actually perform a Conditional Request (don’t worry, its simple), and how to use the JSON API.