Package org.a2aproject.sdk.server.common.quarkus

Class SseResponseWriter

java.lang.Object

org.a2aproject.sdk.server.common.quarkus.SseResponseWriter

public final class SseResponseWriter
extends Object

Utility for writing SSE (Server-Sent Events) responses over Vert.x HTTP.

Events are requested all upfront (request(Long.MAX_VALUE)) so that back-to-back emissions from the EventConsumer are never dropped by a stalled single-item demand window. This means the EventConsumer's internal buffer (256 items) acts as the only bound — write-level backpressure is not applied. Ordering between the final response.write() and response.end() is preserved by EventConsumer.BUFFER_FLUSH_DELAY_MS: the EventConsumer waits briefly after sending the final event before calling tube.complete(), which ensures every write callback has confirmed delivery before onComplete is delivered to this subscriber.

Method Summary

Modifier and Type	Method	Description
static void	writeSseStrings(io.smallrye.mutiny.Multi<String> sseStrings, io.vertx.ext.web.RoutingContext rc, ServerCallContext context, @Nullable Runnable onSubscribedHook)	Subscribes to sseStrings and writes each SSE event to the HTTP response.

Methods inherited from class java.lang.Object

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

Method Details

writeSseStrings

public static void writeSseStrings(io.smallrye.mutiny.Multi<String> sseStrings,
 io.vertx.ext.web.RoutingContext rc,
 ServerCallContext context,
 @Nullable Runnable onSubscribedHook)

Subscribes to sseStrings and writes each SSE event to the HTTP response.

Error handling:

• Client disconnect → cancels upstream, stops polling
• Write failure → cancels upstream, fails routing context
• Stream error → cancels upstream, fails routing context

Parameters:

sseStrings - the SSE-formatted event stream

rc - the Vert.x routing context

context - the A2A server call context (for EventConsumer cancellation)

onSubscribedHook - optional hook invoked once the subscriber is attached; used by tests