Streaming in production in LangChain - Mini Project: Build & Apply

Streaming in production

📖 Scenario: You are building a chatbot application that streams responses from a language model to users in real time. This helps users see the answer as it is generated, improving their experience.

🎯 Goal: Create a Langchain chatbot that streams the language model's output token by token to the user interface.

📋 What You'll Learn

Create a Langchain chat model instance with streaming enabled

Set up a callback handler to process streamed tokens

Implement the chat call to receive streamed tokens

Complete the streaming setup to display tokens as they arrive

💡 Why This Matters

🌍 Real World

Streaming responses improve user experience in chatbots by showing answers as they are generated, reducing wait times.

💼 Career

Many AI-powered applications require streaming outputs for responsiveness, making this skill valuable for AI developers and software engineers.

1

Create the chat model with streaming enabled

Create a variable called chat that is an instance of ChatOpenAI with streaming=True and temperature=0.

LangChain

# Your code here

Need a hint?

Use ChatOpenAI(streaming=True, temperature=0) to create the chat model.

2

Set up a callback handler for streaming tokens

Create a variable called handler that is an instance of StreamingStdOutCallbackHandler from langchain.callbacks.streaming_stdout.

LangChain

from langchain.callbacks.streaming_stdout import StreamingStdOutCallbackHandler

# Your code here

Need a hint?

Import and instantiate StreamingStdOutCallbackHandler as handler.

3

Call the chat model with streaming callbacks

Call chat with messages set to a list containing a HumanMessage with content 'Hello, how are you?', and pass callbacks=[handler] to enable streaming. Assign the result to response.

LangChain

# Your code here

Need a hint?

Use chat(messages=[HumanMessage(content='Hello, how are you?')], callbacks=[handler]) and assign to response.

4

Print the final response content

Print the content attribute of response to display the full answer after streaming.

LangChain

# Your code here

Need a hint?

Use print(response.content) to show the full response after streaming.