barchartnestedvisualization.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v2.json",
/* Resizing the Visualtization */
  "autosize": "none",
  "width": 500,
  "height": 300,
  "padding": 45,
  "title": "Top Category Count",
  "data": {
    "url": {
      "%context%": true,
      "%timefield%": "timestamp",
      "index": "test",
  /* adding a Nested Documentation Data */
      "body": {
        "size": 0,
        "aggs": {
          "a": {
            "nested": {"path": "headers"},
            "aggs": {
              "b": {
                "filter": {
                  "bool": {
                    "filter": [
                      {"term": {"headers.name.keyword": "Category"}}
                    ]
                  }
                },
                "aggs": {"c": {"terms": {"field": "headers.value.keyword"}}}
              }
            }
          }
        }
      }
    },
    "format": {"type": "json", "property": "aggregations.a.b.c.buckets"}
  },
/* adding limitation only less than 10 */
    "transform": [
    {"window": [{"op": "count", "as": "count"}]},
    {"filter": "datum.count <= 10"}
  ],
/* adding a Bar Chart */
  "mark": {"type": "bar", "cornerRadiusEnd": 8},
  "encoding": {
    "x": {"field": "key", "type": "ordinal", "title": "Category", "sort": {"field": "doc_count", "order": "descending" },"axis": {"labelAngle": 0}},
    "y": {"field": "doc_count", "type": "quantitative", "title": "Number of Requests"}
  }
}

adding visualisation of BAR Chart