1. A method, comprising: receiving, at a visualization service, a first query from a client to visualize data in a stream processing application, wherein the stream processing application comprises a plurality of operators that are connected to process a stream of input data, wherein each operator comprises executable software, wherein one or more of the operators is a query-able operator that contains functionality to receive new queries during operation; sending the first query from the visualization service to a query-able operator of the stream processing application; performing, at a query-able operator, an operation using history data in the query-able operator to produce a first result that satisfies the first query and sending the first result to the visualization service; receiving new data at the query-able operator, and, in response, performing an operation using the new data to produce a second result that satisfies the first query and sending the second result to the visualization service; and outputting, from the visualization service, the first and second results to the client.