Window support

When you write a primitive operator, you might need to maintain a set of recently processed input tuples to compute the operator output. It might be sufficient to use Streams Processing Language (SPL) support for windows.

At the operator invocation side, SPL provides the window clause, which allows configuring the window that is used by each input port of the operator. At the primitive operator implementation side, SPL offers the windowing library, which is an event-based library that simplifies the implementation of different window policies. This library can be used when you develop primitive operators in C++ and in Java™.