1. A system for processing of data streams, the system comprising: at least one stream processing module that receives one or more input streams of data and produces one or more streams of output data; and a spreadsheet module that repeatedly performs a two-step cycle in which during the first step, new output data from said at least one stream processing module is input into spreadsheet cells of the spreadsheet, and then in the second step the spreadsheet module recalculates values in the spreadsheet cells based on the new output data provided during the first step of the cycle.