persist until succeed
{"Image ImageWidth": "1280", "Image ImageLength": "960", "Image BitsPerSample": "[8, 8, 8]", "Image PhotometricInterpretation": "2", "Image Make": "Apple", "Image Model": "iPhone 5", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "3", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS5 Macintosh", "Image DateTime": "2013:10:20 14:23:41", "Image HostComputer": "iPhone (iPhone OS 7.0.2)", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "320", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "610", "Thumbnail JPEGInterchangeFormatLength": "5600", "EXIF FNumber": "14/5", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2013:09:28 12:18:22", "EXIF DateTimeDigitized": "2013:09:28 12:18:22", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ApertureValue": "1485427/500000", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "650", "EXIF ExifImageLength": "436", "EXIF SceneCaptureType": "Standard"}