json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema",
      "title": "Rectangle",
      "description": "A rectangle from diagroo app - http://ow.ly/WSX8I",
      "type": "object",
      "required": [
          "width",
          "height"
      ],
      "properties": {
          "width": {
              "type": "integer",
              "minimum": 1
          },
          "height": {
              "type": "integer",
              "minimum": 1
          },
          "rotation": {
              "type": "number",
              "minimum": -360,
              "maximum": 360
          }
      }
  }