Java Operator API overview

The Javadoc documentation for this API is provided with the InfoSphere Streams installation in the $STREAMS_INSTALL/doc/spl/operator/api/java/api directory. The primary package within this API iscom.ibm.streams.operator. Here is a brief description of its main classes.

• Operator: This interface defines an operator. The InfoSphere Streams run time calls methods on this interface for initialization and then on for each incoming tuple and punctuation until a shutdown request is made.
• AbstractOperator: Is an abstract class that developers can extend to implement Operator. It provides a number of useful utility methods.
• OperatorContext: This interface provides access to the operator's runtime context, including descriptions of the streams and parameters. In addition, it provides access to a Java ScheduledExectorService and ThreadFactory for asynchronous actions.
• StreamSchema: This interface describes the schema of a port, including the names and types (Java and SPL) of its attributes.
• StreamingInput: This interface describes an input port, including its schema.
• StreamingOutput: This interface describes an output port and provides methods to obtain new output tuples and to submit them.
• Tuple: This interface implements an immutable object that generically represents an incoming tuple.
• OutputTuple: This interface implements a mutable object that generically represents an outgoing tuple.

The Java Operator API is in the InfoSphere Streams library com.ibm.streams.operator.jar, which is located in $STREAMS_INSTALL/lib. The Java Operator API depends on Apache Commons Math 2.2 library (commons-math-2.2.jar) which is located in $STREAMS_INSTALL/ext/lib. When you develop Java operators using the Java Operator API, the com.ibm.streams.operator.jar and commons-math-2.2.jar libraries are required in the class path or build environment for the InfoSphere Streams Studio. Sample operators and patterns, including source, are supplied in the InfoSphere Streams library com.ibm.streams.operator.samples.jar, which is in $STREAMS_INSTALL/lib.