LangServe for API deployment in LangChain - Mini Project: Build & Apply

Deploy a Simple API with LangServe

📖 Scenario: You want to create a simple API that answers questions using a language model. LangServe helps you deploy this API easily.

🎯 Goal: Build a basic LangServe API that accepts a question and returns an answer from a language model.

📋 What You'll Learn

Create a LangChain language model instance

Set up LangServe API configuration

Write the main API logic to handle questions

Complete the API deployment code

💡 Why This Matters

🌍 Real World

LangServe lets developers quickly deploy language model APIs for chatbots, assistants, or data queries.

💼 Career

Knowing LangServe helps you build and deploy AI-powered APIs, a valuable skill in AI and backend development roles.

1

Create the language model instance

Create a variable called llm that is an instance of OpenAI with temperature=0.

LangChain

# Your code here

Need a hint?

Use OpenAI(temperature=0) to create the language model instance.

2

Set up LangServe API configuration

Create a variable called app that is an instance of LangServe with the llm you created.

LangChain

from langchain.llms import OpenAI

llm = OpenAI(temperature=0)
# Your code here

Need a hint?

Use LangServe(llm=llm) to create the API app.

3

Write the main API logic

Define a function called answer_question that takes a parameter question and returns app.llm(question).

LangChain

from langchain.llms import OpenAI
from langchain.server import LangServe

llm = OpenAI(temperature=0)
app = LangServe(llm=llm)
# Your code here

Need a hint?

Define a function that calls app.llm with the question.

4

Complete the API deployment code

Add the line app.run() at the end to start the LangServe API server.

LangChain

from langchain.llms import OpenAI
from langchain.server import LangServe

llm = OpenAI(temperature=0)
app = LangServe(llm=llm)

def answer_question(question: str) -> str:
    return app.llm(question)
# Your code here

Need a hint?

Call app.run() to start the API server.