A great example of a use case where JSON will not work:
http://developer.ebay.com/Devzone/XML/docs/Reference/ebay/index.html
Sen Rong Poh
It's not on the immediate roadmap for now, but we're looking into how we can better support apps that only take XML requests. In the meantime, the SDK might be a good stop-gap solution.
Sen Rong Poh
Good news! Apparently this was implemented some time back, but we missed out on updating the hint below to say that XML is supported. Refer to this recipe for an example of how to send requests using an XML-formatted body.
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Jeremy Farber
Allow XML in Request Body for HTTP Request
The fact that you guys only allow JSON in the request body is very limiting. Not every API service uses JSON, some use XML.
Your REST connector is incomplete without this.