Processor Contract — Stream Processing Node

Processor is the main abstraction of the Low-Level Processor API for record stream processors (aka stream processing nodes) that can process one record at a time.

Processor can be added to a Topology using Topology.addProcessor operator (via ProcessorSupplier).

Note	Streams DSL — High-Level Stream Processing DSL comes with the KStream.process operator to add a custom `Processor` to a topology (via ProcessorSupplier).

The lifecycle of a Processor is fully controlled by a corresponding ProcessorNode.

Table 1. Processor Contract
Method	Description
`close`	`void close()` Closes the processor Used exclusively when `ProcessorNode` is requested to close.
`init`	`void init(ProcessorContext context)` Initializes the processor with a ProcessorContext (that can be used to decide whether a record should be forwarded downstream to child processors if there are any) Used exclusively when `ProcessorNode` is requested to init
`process`	`void process(K key, V value)` Processes a single record (as a pair of a `K` key and a `V` value) Used exclusively when `ProcessorNode` is requested to process a single record (as a key and value pair).

Tip	Use AbstractProcessor when you want to develop a custom `Processor`.

Table 2. Processors (Direct Implementations)
Processor	Description
AbstractProcessor	Abstract processor that manages a ProcessorContext instance and provides a no-op close implementation
KStreamTransformValuesProcessor
KTableSuppressProcessor

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