Package com.langfuse.client.core

Class SseEventParser

java.lang.Object

com.langfuse.client.core.SseEventParser

public final class SseEventParser
extends Object

Utility class for parsing Server-Sent Events with support for discriminated unions.

Handles two discrimination patterns:

1. Data-level discrimination: The discriminator (e.g., 'type') is inside the JSON data payload. Jackson's polymorphic deserialization handles this automatically.
2. Event-level discrimination: The discriminator (e.g., 'event') is at the SSE envelope level. This requires constructing the full SSE envelope for Jackson to process.

Method Summary

Modifier and Type	Method	Description
static Optional<String>	findDiscriminatorProperty(Class<?> unionClass)	Attempts to find the discriminator property from the union class's Jackson annotations.
static boolean	isEventLevelDiscrimination(String discriminatorProperty)	Determines if the given discriminator property indicates event-level discrimination.
static <T> T	parseDataLevelUnion(String data, Class<T> valueType)	Parse an SSE event using data-level discrimination.
static <T> T	parseEventLevelUnion(String eventType, String data, String id, Long retry, Class<T> unionClass, String discriminatorProperty)	Parse an SSE event using event-level discrimination.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

parseEventLevelUnion

public static <T> T parseEventLevelUnion(String eventType,
 String data,
 String id,
 Long retry,
 Class<T> unionClass,
 String discriminatorProperty)

Parse an SSE event using event-level discrimination.

Constructs the full SSE envelope object with event, data, id, and retry fields, then deserializes it to the target union type.

Type Parameters:

T - The target type

Parameters:

eventType - The SSE event type (from event: field)

data - The SSE data content (from data: field)

id - The SSE event ID (from id: field), may be null

retry - The SSE retry value (from retry: field), may be null

unionClass - The target union class

discriminatorProperty - The property name used for discrimination (e.g., "event")

Returns:

The deserialized object

parseDataLevelUnion

public static <T> T parseDataLevelUnion(String data,
 Class<T> valueType)

Parse an SSE event using data-level discrimination.

Simply parses the data field as JSON and deserializes it to the target type. Jackson's polymorphic deserialization handles the discrimination automatically.

Type Parameters:

T - The target type

Parameters:

data - The SSE data content (from data: field)

valueType - The target type

Returns:

The deserialized object

isEventLevelDiscrimination

public static boolean isEventLevelDiscrimination(String discriminatorProperty)

Determines if the given discriminator property indicates event-level discrimination. Event-level discrimination occurs when the discriminator is an SSE envelope field.

Parameters:

discriminatorProperty - The discriminator property name

Returns:

true if event-level discrimination, false otherwise

findDiscriminatorProperty

public static Optional<String> findDiscriminatorProperty(Class<?> unionClass)

Attempts to find the discriminator property from the union class's Jackson annotations.

Parameters:

unionClass - The union class to inspect

Returns:

The discriminator property name, or empty if not found