Now, the moment we have all been waiting for; we can see average stock prices over time by using the REST API that Druid provides. To use the REST API, it is not necessary to run a full-blown Druid cluster. You will only be able to query the data seen by the singular embedded real-time node, but each node is capable of servicing requests and this makes testing easier. Using curl, you can issue a query of a real-time node using the following command:

curl -sX POST "http://localhost:7070/druid/v2/?pretty=true" -H 'content-type: application/json'  -d @storm_query

The final parameter of the curl statement references a file, the contents of which will be included as the body of the POST request. The file contains the following details:

{
    "queryType": "groupBy",
    "dataSource": "stockinfo",
    "granularity": "minute",
    "dimensions": ["symbol"],
    "aggregations":[
        { "type": "longSum", "fieldName": "orders",
         "name": "cumulativeCount"},
       ...