Package akka.javasdk.agent

Interface Classifier

public interface Classifier

A classifier maps an input to a Classification — a score and/or label, with optional confidence and metadata. Can be implemented with rules or regex, embeddings, traditional ML, a small specialised model, a prompted or fine-tuned LLM, or an external classification API — the implementation is just user code calling out to whatever it needs.

An implementation has a public constructor into which the platform's managed dependencies can be injected — including a ClassifierClient, for composing other configured classifiers (for example, an ensemble classifier combining several underlying ones), and a ClassifierContext for the classifier's configured name and config section.

Unlike a Guardrail, a classifier is never bound to a call boundary and is never dispatched by the runtime. It is invoked inline, wherever a guardrail, an evaluator, or application code needs it, through an injected ClassifierClient by name.

Classifiers are enabled with configuration; see agent documentation.

Method Summary

Modifier and Type	Method	Description
Classification	classify(String input)	Classifies input and returns the resulting Classification.
default CompletionStage<Classification>	classifyAsync(String input)	Async variant of classify(java.lang.String), for implementations that prefer composing futures.

Method Details

classify

Classification classify(String input)

Classifies input and returns the resulting Classification.

This is the method to implement. It may block: classifiers are always invoked on virtual threads.

Returns:

the classification

classifyAsync

default CompletionStage<Classification> classifyAsync(String input)

Async variant of classify(java.lang.String), for implementations that prefer composing futures.

The default implementation delegates to classify(java.lang.String). When this method is overridden, classify(java.lang.String) is no longer used, and it is then safe to have it throw UnsupportedOperationException or return null.

Returns:

a CompletionStage with the classification