Frames: data-driven windows.

Traditional Data Stream Management Systems (DSMS) segment data streams using windows that are defined either by a time interval or a number of tuples. Such windows are fixed---the definition unvarying over the course of a stream---and are defined based on external properties unrelated to the data content of the stream. However, streams and their content do vary over time---the rate of a data stream may vary or the data distribution of the content may vary. The mismatch between a fixed stream segmentation and a variable stream motivates the need for a more flexible, expressive and physically independent stream segmentation. We introduce a new stream segmentation technique, called frames. Frames segment streams based on data content. We present a theory and implementation of frames and show the utility of frames for a variety of applications.