1. A system for processing of data streams, the system comprising: at least one computer system including at least a processor and memory; at least one stream processing module that receives one or more input data streams and produces one or more output data streams, wherein each of the input data streams and output data streams are a time-ordered group of files concatenated together; a spreadsheet module that repeatedly performs a two-step cycle in which during the first step, the output data streams produced by said at least one stream processing module are entered into particular spreadsheet cells of a spreadsheet, and then in the second step, the spreadsheet module calculates values in the spreadsheet based on the output data streams entered into particular spreadsheet cells of the spreadsheet during the first step of the cycle; and a plug-in module to said spreadsheet module enabling a user to: design said at least one stream processing module utilizing the spreadsheet module, and select data for processing by said at least one stream processing module, wherein the plug-in module specifies rows and columns of the output data streams produced by said at least one stream processing module, enters the output data streams into particular spreadsheet cells of the spreadsheet, and performs calculations by the spreadsheet module on the output data streams entered into the particular spreadsheet cells of the spreadsheet, wherein said at least one stream processing module is external to the spreadsheet and the plug-in module.