message_format.json

{   
    "options":[
        {
            "action": "fit",
            "size": "100x100",
            "format": "png",
            "mime": "image/png",
            "prefix": "resized-image-fit"
        },
        {
            "action": "fill",
            "size": "200x200",
            "format": "png",
            "mime": "image/png",
            "prefix": "resized-image-fill"
        },
        {
            "action": "center",
            "size": "300x300",
            "format": "png",
            "mime": "image/png",
            "prefix": "resized-image-center"
        },
        {
            "action": "width",
            "size": "100",
            "format": "png",
            "mime": "image/png",
            "prefix": "resized-image-width"
        },
        {
            "action": "height",
            "size": "150",
            "format": "png",
            "mime": "image/png",
            "prefix": "resized-image-height"
        },
        {
            "action": "stretch",
            "size": "120x120",
            "format": "png",
            "mime": "image/png",
            "prefix": "resized-image-stretch"
        },
        {
            "action": "thumb",
            "size": "50x50",
            "format": "png",
            "mime": "image/png",
            "prefix": "resized-image-thumb"
        }
    ],
    "params":{
        "custom": "These params are going to be sent to response channel, you can put anything here.",
        "other": "You can use this part as informational data area."
    },
    "response_channel":"image_resized",
    "key":"image.jpg",
    "bucket_name":"your-bucket-name"
}