Feature/sse (#3125)

* Base changes for ServerSide Events (instead of socket.io)

* lint fixes

* adding of interface and separate methods for streaming events

* lint

* first draft, handles both internal and external prediction end points.

* lint fixes

* additional internal end point for streaming and associated changes

* return streamresponse as true to build agent flow

* 1) JSON formatting for internal events
2) other fixes

* 1) convert internal event to metadata to maintain consistency with external response

* fix action and metadata streaming

* fix for error when agent flow is aborted

* prevent subflows from streaming and other code cleanup

* prevent streaming from enclosed tools

* add fix for preventing chaintool streaming

* update lock file

* add open when hidden to sse

* Streaming errors

* Streaming errors

* add fix for showing error message

---------

Co-authored-by: Henry <hzj94@hotmail.com>

packages/components/nodes/engine/ChatEngine/SimpleChatEngine.ts

@@ -1,4 +1,13 @@
-import { FlowiseMemory, ICommonObject, IMessage, INode, INodeData, INodeOutputsValue, INodeParams } from '../../../src/Interface'
+import {
+    FlowiseMemory,
+    ICommonObject,
+    IMessage,
+    INode,
+    INodeData,
+    INodeOutputsValue,
+    INodeParams,
+    IServerSideEventStreamer
+} from '../../../src/Interface'
 import { LLM, ChatMessage, SimpleChatEngine } from 'llamaindex'
 
 class SimpleChatEngine_LlamaIndex implements INode {
@@ -86,18 +95,24 @@ class SimpleChatEngine_LlamaIndex implements INode {
 
         let text = ''
         let isStreamingStarted = false
-        const isStreamingEnabled = options.socketIO && options.socketIOClientId
 
-        if (isStreamingEnabled) {
+        const shouldStreamResponse = options.shouldStreamResponse
+        const sseStreamer: IServerSideEventStreamer = options.sseStreamer as IServerSideEventStreamer
+        const chatId = options.chatId
+
+        if (shouldStreamResponse) {
             const stream = await chatEngine.chat({ message: input, chatHistory, stream: true })
             for await (const chunk of stream) {
                 text += chunk.response
                 if (!isStreamingStarted) {
                     isStreamingStarted = true
-                    options.socketIO.to(options.socketIOClientId).emit('start', chunk.response)
+                    if (sseStreamer) {
+                        sseStreamer.streamStartEvent(chatId, chunk.response)
+                    }
+                }
+                if (sseStreamer) {
+                    sseStreamer.streamTokenEvent(chatId, chunk.response)
                 }
-
-                options.socketIO.to(options.socketIOClientId).emit('token', chunk.response)
             }
         } else {
             const response = await chatEngine.chat({ message: input, chatHistory })