How to configure multiple streaming modes at the same time

This guide covers how to configure multiple streaming modes at the same time.

Setup

First we need to install the packages required

npm install @langchain/langgraph @langchain/openai @langchain/core

Next, we need to set API keys for OpenAI (the LLM we will use)

export OPENAI_API_KEY=your-api-key

Optionally, we can set API key for LangSmith tracing, which will give us best-in-class observability.

export LANGCHAIN_TRACING_V2="true"
export LANGCHAIN_CALLBACKS_BACKGROUND="true"
export LANGCHAIN_API_KEY=your-api-key

Define the graph

We'll be using a prebuilt ReAct agent for this guide.

import { ChatOpenAI } from "@langchain/openai";
import { tool } from '@langchain/core/tools';
import { z } from 'zod';
import { createReactAgent } from "@langchain/langgraph/prebuilt";

const model = new ChatOpenAI({
    model: "gpt-4o",
  });

const getWeather = tool((input) => {
  if (["sf", "san francisco", "san francisco, ca"].includes(input.location.toLowerCase())) {
    return "It's 60 degrees and foggy.";
  } else {
    return "It's 90 degrees and sunny.";
  }
}, {
  name: "get_weather",
  description: "Call to get the current weather.",
  schema: z.object({
    location: z.string().describe("Location to get the weather for."),
  })
})

const graph = createReactAgent({ llm: model, tools: [getWeather] });

Stream Multiple

To get multiple types of streamed chunks, pass an array of values under the streamMode key in the second argument to .stream():

let inputs = { messages: [{ role: "user", content: "what's the weather in sf?" }] };

let stream = await graph.stream(inputs, {
  streamMode: ["updates", "debug"],
});

for await (const chunk of stream) {
  console.log(`Receiving new event of type: ${chunk[0]}`);
  console.log(chunk[1]);
  console.log("\n====\n");
}

Receiving new event of type: debug
{
  type: 'task',
  timestamp: '2024-08-30T20:58:58.404Z',
  step: 1,
  payload: {
    id: '768110dd-6004-59f3-8671-6ca699cccd71',
    name: 'agent',
    input: { messages: [Array] },
    triggers: [ 'start:agent' ],
    interrupts: []
  }
}

====

Receiving new event of type: updates
{
  agent: {
    messages: [
      AIMessage {
        "id": "chatcmpl-A22zqTwumhtW8TMjQ1FxlzCEMBk0R",
        "content": "",
        "additional_kwargs": {
          "tool_calls": [
            {
              "id": "call_HAfilebE1q9E9OQHOlL3JYHP",
              "type": "function",
              "function": "[Object]"
            }
          ]
        },
        "response_metadata": {
          "tokenUsage": {
            "completionTokens": 15,
            "promptTokens": 59,
            "totalTokens": 74
          },
          "finish_reason": "tool_calls",
          "system_fingerprint": "fp_157b3831f5"
        },
        "tool_calls": [
          {
            "name": "get_weather",
            "args": {
              "location": "San Francisco"
            },
            "type": "tool_call",
            "id": "call_HAfilebE1q9E9OQHOlL3JYHP"
          }
        ],
        "invalid_tool_calls": [],
        "usage_metadata": {
          "input_tokens": 59,
          "output_tokens": 15,
          "total_tokens": 74
        }
      }
    ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task_result',
  timestamp: '2024-08-30T20:58:59.072Z',
  step: 1,
  payload: {
    id: '768110dd-6004-59f3-8671-6ca699cccd71',
    name: 'agent',
    result: [ [Array] ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task',
  timestamp: '2024-08-30T20:58:59.074Z',
  step: 2,
  payload: {
    id: '76459c18-5621-5893-9b93-13bc1db3ba6d',
    name: 'tools',
    input: { messages: [Array] },
    triggers: [ 'branch:agent:shouldContinue:tools' ],
    interrupts: []
  }
}

====

Receiving new event of type: updates
{
  tools: {
    messages: [
      ToolMessage {
        "content": "It's 60 degrees and foggy.",
        "name": "get_weather",
        "additional_kwargs": {},
        "response_metadata": {},
        "tool_call_id": "call_HAfilebE1q9E9OQHOlL3JYHP"
      }
    ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task_result',
  timestamp: '2024-08-30T20:58:59.076Z',
  step: 2,
  payload: {
    id: '76459c18-5621-5893-9b93-13bc1db3ba6d',
    name: 'tools',
    result: [ [Array] ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task',
  timestamp: '2024-08-30T20:58:59.077Z',
  step: 3,
  payload: {
    id: '565d8a53-1057-5d83-bda8-ba3fada24b70',
    name: 'agent',
    input: { messages: [Array] },
    triggers: [ 'tools' ],
    interrupts: []
  }
}

====

Receiving new event of type: updates
{
  agent: {
    messages: [
      AIMessage {
        "id": "chatcmpl-A22zrdeobsBzkiES0C6Twh3p7I344",
        "content": "The weather in San Francisco right now is 60 degrees and foggy.",
        "additional_kwargs": {},
        "response_metadata": {
          "tokenUsage": {
            "completionTokens": 16,
            "promptTokens": 90,
            "totalTokens": 106
          },
          "finish_reason": "stop",
          "system_fingerprint": "fp_157b3831f5"
        },
        "tool_calls": [],
        "invalid_tool_calls": [],
        "usage_metadata": {
          "input_tokens": 90,
          "output_tokens": 16,
          "total_tokens": 106
        }
      }
    ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task_result',
  timestamp: '2024-08-30T20:58:59.640Z',
  step: 3,
  payload: {
    id: '565d8a53-1057-5d83-bda8-ba3fada24b70',
    name: 'agent',
    result: [ [Array] ]
  }
}

====