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Return json rpc when sending SSE events in streaming #689

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48ed813
Return json rpc when sending SSE events in streaming
abadongutierrez Aug 10, 2025
24d8dfb
Change flow when message/stream.
abadongutierrez Aug 12, 2025
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88 changes: 40 additions & 48 deletions ...bel-agent-api/src/main/kotlin/com/embabel/agent/a2a/server/support/A2AStreamingHandler.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -63,15 +63,9 @@ class A2AStreamingHandler(
activeStreams.remove(streamId)
}

// Send initial connection established event
try {
emitter.send(SseEmitter.event()
.name("connected")
.data(mapOf("streamId" to streamId))
)
} catch (e: Exception) {
logger.error("Error sending initial event", e)
emitter.completeWithError(e)
emitter.onError { throwable ->
logger.error("Stream error for streamId: {}", streamId, throwable)
activeStreams.remove(streamId)
}

return emitter
Expand All @@ -88,49 +82,15 @@ class A2AStreamingHandler(

try {
val eventData = when (event) {
is Message -> {
SseEmitter.event()
.name("message")
.data(objectMapper.writeValueAsString(event), MediaType.APPLICATION_JSON)
}
is Task -> {
SseEmitter.event()
.name("task")
.data(objectMapper.writeValueAsString(event), MediaType.APPLICATION_JSON)
}
is TaskStatusUpdateEvent -> {
SseEmitter.event()
.name("task-update")
.data(
objectMapper.writeValueAsString(
SendStreamingMessageResponse(
"2.0",
streamId,
event,
null
)
), MediaType.APPLICATION_JSON
)
}
is TaskArtifactUpdateEvent -> {
SseEmitter.event()
.name("task-update")
.data(
objectMapper.writeValueAsString(
SendStreamingMessageResponse(
"2.0",
streamId,
event,
null
)
), MediaType.APPLICATION_JSON
)
is Message, is Task, is TaskArtifactUpdateEvent, is TaskStatusUpdateEvent -> {
createEventData(streamId, event)
}
}
emitter.send(eventData)
} catch (e: Exception) {
logger.error("Error sending stream event", e)
emitter.completeWithError(e)
logger.error("Error sending stream event to streamId: {}", streamId, e)
val emitter = activeStreams.remove(streamId)
emitter?.completeWithError(e)
}
}

Expand All @@ -142,16 +102,48 @@ class A2AStreamingHandler(
emitter?.complete()
}

private fun createEventData(streamId: String, event: StreamingEventKind): SseEmitter.SseEventBuilder {
val eventName = when (event) {
is Message -> "message"
is Task -> "task"
is TaskStatusUpdateEvent, is TaskArtifactUpdateEvent -> "task-update"
}

val response = SendStreamingMessageResponse(
"2.0",
streamId,
event,
null
)

return SseEmitter.event()
.name(eventName)
.data(objectMapper.writeValueAsString(response), MediaType.APPLICATION_JSON)
}

/**
* Shuts down the streaming handler
*/
fun shutdown() {
logger.info("Shutting down, closing {} active streams", activeStreams.size)
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Code here was suggested by AI but, imho, looks good


activeStreams.values.forEach { emitter ->
try {
emitter.complete()
} catch (e: Exception) {
logger.warn("Error completing emitter during shutdown", e)
}
}
activeStreams.clear()

scheduler.shutdown()
try {
if (!scheduler.awaitTermination(5, TimeUnit.SECONDS)) {
logger.warn("Scheduler did not terminate gracefully, forcing shutdown")
scheduler.shutdownNow()
}
} catch (e: InterruptedException) {
Thread.currentThread().interrupt()
scheduler.shutdownNow()
}
}
Expand Down
83 changes: 54 additions & 29 deletions ...ent-api/src/main/kotlin/com/embabel/agent/a2a/server/support/AutonomyA2ARequestHandler.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -163,23 +163,34 @@ class AutonomyA2ARequestHandler(
val emitter = streamingHandler.createStream(streamId)

Thread.startVirtualThread {
val taskId = ensureTaskId(params.message.taskId)
val contextId = ensureContextId(params.message.contextId)
val taskStatusUpdateEventBuilder = TaskStatusUpdateEvent.Builder()
.taskId(taskId)
.contextId(contextId)
val taskBuilder = Task.Builder()
.id(taskId)
.contextId(contextId)

try {
// Send initial status event
// Send task submitted
val taskSubmitted = taskBuilder
.status(createSubmittedTaskStatus(taskId, contextId))
.history(listOfNotNull(params.message))
.artifacts(emptyList())
.metadata(null)
.build()
streamingHandler.sendStreamEvent(streamId, taskSubmitted)

// Send status before running the agent
streamingHandler.sendStreamEvent(
streamId, TaskStatusUpdateEvent.Builder()
.taskId(params.message.taskId)
.contextId(params.message.contextId)
.status(createWorkingTaskStatus(params, "Task started..."))
streamId, taskStatusUpdateEventBuilder
.status(createWorkingTaskStatus(params, "Starting task..."))
.build()
)

// Send the received message, if any
params.message?.let { userMsg ->
streamingHandler.sendStreamEvent(streamId, userMsg)
}

val intent = params.message?.parts?.filterIsInstance<TextPart>()?.firstOrNull()?.text
?: "Task ${params.message.taskId}"
?: "Task ${taskId}"

// Execute the task using autonomy service
val result = autonomy.chooseAndRunAgent(
Expand All @@ -190,35 +201,28 @@ class AutonomyA2ARequestHandler(

// Send intermediate status updates
streamingHandler.sendStreamEvent(
streamId, TaskStatusUpdateEvent.Builder()
.taskId(params.message.taskId)
.contextId(ensureContextId(params.message.contextId))
streamId, taskStatusUpdateEventBuilder
.status(createWorkingTaskStatus(params, "Processing task..."))
.build()
)

// Send result
val taskResult = Task.Builder()
.id(params.message.taskId)
.contextId("ctx_${UUID.randomUUID()}")
.status(createCompletedTaskStatus(params))
val taskResult = taskBuilder
.status(createCompletedTaskStatus(taskId, contextId))
.history(listOfNotNull(params.message))
.artifacts(
listOf(
createResultArtifact(result, params.configuration?.acceptedOutputModes)
)
)
.metadata(null)
.build()
streamingHandler.sendStreamEvent(streamId, taskResult)
} catch (e: Exception) {
logger.error("Streaming error", e)
try {
streamingHandler.sendStreamEvent(
streamId, TaskStatusUpdateEvent.Builder()
.taskId(params.message.taskId)
.contextId(ensureContextId(params.message.contextId))
.status(createFailedTaskStatus(params, e))
streamId, taskStatusUpdateEventBuilder
.status(createFailedTaskStatus(taskId, contextId, e))
.build()
)
} catch (sendError: Exception) {
Expand Down Expand Up @@ -246,29 +250,34 @@ class AutonomyA2ARequestHandler(
TODO()
}

private fun createFailedTaskStatus(params: MessageSendParams, e: Exception): TaskStatus = TaskStatus(
private fun createFailedTaskStatus(
taskId: String,
contextId: String,
e: Exception
): TaskStatus = TaskStatus(
TaskState.FAILED,
Message.Builder()
.messageId(UUID.randomUUID().toString())
.role(Message.Role.AGENT)
.parts(listOf(TextPart("Error: ${e.message}")))
.contextId(params.message.contextId)
.taskId(params.message.taskId)
.contextId(contextId)
.taskId(taskId)
.build(),
LocalDateTime.now()
)

private fun createCompletedTaskStatus(
params: MessageSendParams,
taskId: String,
contextId: String,
textPart: String = "Task completed successfully"
): TaskStatus = TaskStatus(
TaskState.COMPLETED,
Message.Builder()
.messageId(UUID.randomUUID().toString())
.role(Message.Role.AGENT)
.parts(listOf(TextPart(textPart)))
.contextId(params.message.contextId)
.taskId(params.message.taskId)
.contextId(contextId)
.taskId(taskId)
.build(),
LocalDateTime.now()
)
Expand All @@ -288,6 +297,22 @@ class AutonomyA2ARequestHandler(
LocalDateTime.now()
)

private fun createSubmittedTaskStatus(
taskId: String,
contextId: String,
textPart: String = "Submitted..."
): TaskStatus = TaskStatus(
TaskState.SUBMITTED,
Message.Builder()
.messageId(UUID.randomUUID().toString())
.role(Message.Role.AGENT)
.parts(listOf(TextPart(textPart)))
.contextId(contextId)
.taskId(taskId)
.build(),
LocalDateTime.now()
)

private fun ensureContextId(providedContextId: String?): String {
return providedContextId ?: ("ctx_" + UUID.randomUUID().toString())
}
Expand Down
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