To override the Content-type in your clients HTTP Accept Header, append  the .json suffix or  ?format=json
To embed the response in a jsonp callback, append ?callback=myCallback
        
        HTTP + JSON
         The following are sample HTTP requests and responses. 
            The placeholders shown need to be replaced with actual values.
POST /json/oneway/ContractFile HTTP/1.1 
Host: scanning.modernekonomi.se 
Content-Type: application/json
Content-Length: length
{"ClientId":0,"Id":0,"FileId":0,"Attachment":false}