A computer system including instructions recorded on a computer-readable medium, the system comprising: a query handler configured to receive a query specified in a unified window specification, UWS, from a stream application to be applied against a stream of data including multiple tuples representing events, wherein the UWS is implemented as an extension to standard SQL comprising additional features specific to event stream processing including a window definition used to define windows on event streams with unified windows semantics; a stream window manager configured to express the query in a specification which defines a window including a subset of the tuples, the specification defining content of the window as a range of the tuples having a range attribute over which the content is specified, defining when to update the window using a synchronization attribute specifying a movement of the window over time with respect to the content, and defining an evaluation of the content of the window using an evaluation attribute specifying when to perform the evaluation; a query translator configured to translate the query including mapping the range attribute, the synchronization attribute, and the evaluation attribute to a stream processing language of a data stream management system, DSMS,, to thereby obtain a translated query; wherein translating the query comprises: - using a parser for parsing the query and for constructing a corresponding parse tree; and - rewriting the query into the stream processing language of the DSMS; and a DSMS mediator configured to provide the translated query to the DSMS for processing therewith. a query handler configured to receive a query specified in a unified window specification, UWS, from a stream application to be applied against a stream of data including multiple tuples representing events, wherein the UWS is implemented as an extension to standard SQL comprising additional features specific to event stream processing including a window definition used to define windows on event streams with unified windows semantics; a stream window manager configured to express the query in a specification which defines a window including a subset of the tuples, the specification defining content of the window as a range of the tuples having a range attribute over which the content is specified, defining when to update the window using a synchronization attribute specifying a movement of the window over time with respect to the content, and defining an evaluation of the content of the window using an evaluation attribute specifying when to perform the evaluation; a query translator configured to translate the query including mapping the range attribute, the synchronization attribute, and the evaluation attribute to a stream processing language of a data stream management system, DSMS,, to thereby obtain a translated query; wherein translating the query comprises: - using a parser for parsing the query and for constructing a corresponding parse tree; and - rewriting the query into the stream processing language of the DSMS; and - using a parser for parsing the query and for constructing a corresponding parse tree; and - rewriting the query into the stream processing language of the DSMS; and a DSMS mediator configured to provide the translated query to the DSMS for processing therewith.