{
   "client_id": "123456.7654321",
   "events": [
     {
        "name": "campaign_details",
        "params": {
          "campaign_id": "google_1234",
          "campaign": "Summer_fun",
          "source": "google",
          "medium": "cpc",
          "term": "summer+travel",
          "content": "logolink",
          "session_id": 1231313, // must be integer value
          "engagement_time_msec": "100"
        }
     },
     {
      "name": "purchase",
      "params": {
        "currency": "USD",
        "transaction_id": "T_12345",
        "value": 12.21,
        "coupon": "SUMMER_FUN",
        "shipping": 3.33,
        "tax": 1.11,
        "session_id": 1231313,
        "items": [
          {
            ...
          }
        ]
      }
   ]
  }