Managing multiple windows on an operator graph

A system for processing a stream of tuples, each tuple having one or more attributes, comprising:

• one or more processing elements operating on one or more computer processors configured to processes the attributes from the stream of tuples, each processing element configured to:
• process the attributes of the stream of tuples using stream operators operating on one or more computer processors and corresponding one or more processing elements;
• process, with a first processing method, a group of tuples from the stream of tuples into a grouping window, wherein the first processing method is configured to cause the system to:
• identify a membership condition,
• determine whether the membership condition is met by a tuple from the stream of tuples, and
• include the tuple in the grouping window in response to the membership condition being met, and
• process, with a second processing method, a subgroup of tuples from the group of tuples into a subgrouping window, wherein the second processing method is configured to cause the system to:
• identify a sub-membership condition.
• determine whether the sub-membership condition is met by a tuple from the group of tuples, and
• include the tuple in the subgrouping window in response to the sub-membership condition being met.