What's the data structure that needed by services for posting new node with drupal7 services?
Corrected JSON format and tested on my local environment. 



{
    "body": {
        "und": [
            {
                "value": "IamShen"
            }
        ]
    },
    "type": "shen",
    "field_shen_image": {
        "und": [
            {
                "new": 1,
                "display": 1,
                "fid": 541
            }
        ]
    },
    "title": "justalittletitle"
}