Operators
Operators are the fundamental building blocks of streams processing applications. Operators process tuples in incoming streams and produce output streams as a result.
The programming model for streams processing applications in InfoSphere® Streams is a data flow graph, which means that streaming data flows between nodes on the graph, in a specified direction. The nodes of the graph are the operators.
- Primitive operators
- Cannot be broken down into smaller processing elements. Primitive operators are not composites of other operators.
- Composite operators
- An operator that is implemented in SPL that encapsulates a subgraph
that can be parameterized to make it reusable in multiple streams processing applications.
A main composite operator is a composite operator that encapsulates the entire data flow graph, that is the root of that graph, that has no input ports or output ports, and that when compiled represents a streams processing application.
Ports are the points of connection of operators to a stream. Input ports consume one or more streams, whereas output ports produce a stream.
An operator invocation is an instance of an operator that was defined for a specific context. Every stream is defined by exactly one operator invocation, but the stream can be consumed by any number of operator invocations. Each time a tuple arrives on any of the input ports of an operator invocation, the operator fires and can produce tuples on its output streams.